I’ve been working furiously this week on a 48v battery module and controller to work with the Sunny Island 6048 US Inverter. Coming nicely I think. This will be a good combo.
But there is a kind of identity crisis between the Sunny Island and the grid-tied Sunny Boy. In Germany, where they are made, it is actually illegal to use them together. And it’s all about the grid.
Here in the U.S. too, there is an identity crisis that spans ALL the vendors of solar equipment. And it is ALL about the grid. People want their solar systems to be tied to the grid. In this way, if they need more electricity than their solar system provides, they can get it from the grid. And if they produce more at any particular moment beyond their needs, they can “sell” it back to the grid.
But if the grid goes out, they want it to provide electricity to their home. And there in lies the rub. If you are connected to the grid, you wind up powering the grid. And that can be bad.
So the vendors try to be all things to all people. And they try to come up with ways that will be “legal” and tie to the grid politely, but also be useful stand alone or as a backup system.
So you have:
1. Off grid systems.
2. Grid tied systems.
3. Backup systems.
Now since they all use similar equipment, why can’t somebody just come up with a way to do all of that in one box. Which is kinda/sorta what the Tesla powerwall purports to do.
Worse, the regulations vary from grid to grid and provider to provider.
Coloring all this is a huge backdrop of schizophrenic activity over what the role of the grid should be and what the role of the homeowner whom we are trying to incentivize to install solar.
In 2009 I predicted that we would no sooner free ourselves of the oil companies, than our pals the electric companies who were oh so enthusiastic and encouraging about electric cars would become the new arch enemy. And it has come to pass. Trading one master for another.
In a Pollyanna perfect world, we could of course build a very distributed network on a national scale and power could shunt from area to area as the sun did shine, and local outages could be made up with local rooftop resources and all would be happy. Meanwhile our dear friends at the utility company are doing horrendously cynical backroom deals with “regulators” all too willing to sell out their neighbors for the right amount of cash. Actually any amount will do.
The case in Florida where a constitutional amendment guaranteeing the right to install solar, which was actually a constitutional amendment assuring utility companies that no one could install solar, was so cynically and deliberately designed that it would do the Democratic National Committee proud. With millions spent by the utility companies to advertise and promote this “rights” movement, it did gain a majority of votes. But that was not enough to pass an amendment and so the deliberately fraudulent ruse was defeated. The author gleefully described it as brilliant political ju-jitsu – that is before it failed and when they thought it would probably pass.
This scenario is currently ramping up across the land and it is now a cottage consultant industry to advise utility companies on specifically how to defeat the desires of their “solar” customers. The self-centered world view of these people is frightening in both its scope and stupidity. But we saw it with the telephone companies over the Internet, the oil companies over the electric cars, and now the utility companies with solar. It is encouraging to note that in the end they ALWAYS lose. But the war can be nasty. And this one shapes up to be.
I’m entirely about empowering individuals at the expense of the large corporations and the state. In this case what I see as the solution is to MOSTLY cut the cord.
The idea of selling electricity from your home back into the grid is great. But in practice it isn’t. IF there is an artificial bonus in it in the form of a Feed In Tarriff, that’s nice. But for most of us, we get paid on a new device of the utility industry called “avoided cost of production” which ignores the realities of a “market” for electricity and goes to a theoretical cost of coal by the ton. In actual practice, for natural gas microturbines acting as load feeders, they pay a PREMIUM over market rates for electricity need during times of extreme demand. But here in Missouri the “avoided cost” is a laughable 1.75 cents per kWh. So in summer you buy at 10 cents, which with taxes is actually 12 cents, and sell at 1.75 cents. When I grow up, I want to be a monopoly. Actually I want to be a government, but like the utility companies, I would settle for just being a monopoly.
The cost of equipment and panels to do solar has come down. But it leaves the idea of building excess generating capacity so you can profit from sales to the utility company actually ludicrous in most cases. And if there IS a way to find a seam in the zone, trust that the utilities will move swiftly to close it.
What I would propose is a bit different type of solar system I term “Selfish Solar”. This is a solar system you build for you and your house. It IS connected to the grid. But kind of as a backstop/supplement. We would use the grid if necessary. But we never give or sell back to it. And the concept is to pay the monthly minimum connection fee and not use any of their electricity at all.
If they go down, we don’t want to worry about disconnection issues any more than someone running an electric dryer does now. It just goes down. And our system continues to power our home for hours, days, weeks or forever. If we are little missized, we might use a little bit from the grid, and there are indeed some winters where a week or two of overcast will probably put us in a deficit. So the connection is “valuable”. But we want it to appear to the utility companies as a normal connection, with no trick meter, and no opportunities to pass legislation “fixing” us. A standard 200 amp service panel with no trick anything. In fact, it only runs ONE device. A battery charger.
In the EV community we already know about battery chargers. We can use one, two, or three Chevy Volt battery chargers to produce up to 420vdc. Or, if Jack would get back on task, a single Tesla battery charger will convert 240vac to 400vdc all day long at a smooth 10kw. Actually Tesla now has a 17kW charger in the newer models.
And that is the ONLY connection TO the grid. It runs a simple switched power supply to convert 240vac grid power to 400vdc battery charging power and it has two basic states, on and off. By the way, if the grid goes down, it is off.
All of this DOES require a battery of course. Indeed, let’s stop looking at the battery as an adjunct to a solar system. Let’s mentally get over it and realize that the battery is the HEART of a home power system. We can use the grid, generators, or solar arrays to put energy INTO it and we use an inverter to convert its output to the familiar 240vac to take energy OUT of it.
Electric vehicles, and Tesla most notably, have batteries that start at 300vdc on the empty side, and reach nearly 400vdc on the full side. This is actually a very good operating range for houses in that 240vac is the object of our desire. If you rectify 240vac and feed it into a large capacitor it will charge to the peak voltage of the input 240vac x 1.41 or 340vdc. And of course to EFFICIENTLY generate 240vac, you really need a power supply that is very near to the peak voltage of 340vdc. We would FULLY charge a Tesla pack to 403vdc.
To efficiently charge this 300-400vdc battery bus from solar, we need a maximum power point power supply that takes the photovoltaic output of the panels and converts it to the battery charge voltage. Almost ALL MPPT charge controllers currently have a max PV voltage of 100 or 150 vdc and are sized for 12, 24, 36, or increasingly 48vdc batteries. At power levels, this gives us huge bulky awkward and very expensive cables.
Eight of our Panasonic HIT panels produce 480vdc in full sunlight. This would be ideal for stepping down very efficiently to our 300-400vdc range. But most MPPT controllers don’t do it, and the one we DID find is kind of weeny at 3000 watts. So we have gone to China and asked them to specifically build us one for the Tesla battery pack. 37 kw and hard wired to charge the battery to 400 vdc. It will do up to 100 amps.
And that leaves us with the inverter. Again MOST of them operate off of 48vdc. So we have again gone to China to get them to build us a special 20kW inverter that works off 300-400dc and produces 240vac output.
And that leaves charging your car. ANd we already have a CHAdeMO charger that runs off a battery input of 300-400vdc.
So the needed utility is to center on a common bus of 300-400vdc, and have everything interact with that.
Let me estimate the retail cost of what the famously expensive EVTV would want for all this.
1. 10 kW Tesla charger and controller – $3,000
2. MPTT 37 kw 400 vdc charge controller – $2,000
3. 20 kw array of 64 Panasonic HIT panels – $20,000
4. Tesla 85 kw battery pack $15,000
5. Battery pack controller $2,000
6. 20 kw 400vdc to 240vac Inverter $10,000
7. CHAdeMO Charger $23,000
That looks like $52,000 without my CHAdeMO charge station. On a sunny day of 4.5 hours, this should make about 90kWh solar. We can store 85kWh. And the average American home uses about 31kWh per day. So 2.5 days storage.
The $52,000 is expensive. But it is expensive like an expensive car. And you are your own utility. Freedom. If you can afford all that, you might just have a home LARGER than the Average American home. So you add 8 panel strings until your utility bill goes to connection fee. Sizing is pretty easy here. Overkill is always appropriate.
What about when your house makes more electricity than you can use or store? Unlike the utility company, we can turn our plant off instantly. Just shut down the MPPT controller automatically when the battery gets full. You suffer the crime of having energy fall on your panels that you cannot use. Be selfish about it. Who cares?
The “response” from the utility companies will of course be to raise the minimum monthly “connection fee” and they already attempted this in Utah and Arizona proposing $150 per month as a minimum. I think the legislature gave em $5 but hey, its a start. Kind of like a two drink minimum at a lap-dance stripper bar. And from the same sort of people. At the point where you don’t want to pay it, tell em to pick up their meter and then describe for them in detail where you would like it inserted for storage purposes.
This then is how I see individuals successfully fighting this battle. As always, it will be for those with the resources to be early adopters. But I think the days of a “little bit of solar” adding a 5kw system to the roof are rapidly coming to a close and you are going to have to choose between the grid and the grid-not. Fortunately, the electric vehicles give us the tools to perform this act with dispatch. As more EVs show up, and as more people move to a 400v bus compatible with the car batteries, I think all of this gets cheaper. In five to eight years, probably that entire system will be doable in the $20k range.
And so I would advocate not worrying about grid tie and indeed not view your home as contributing power to the grid and system. It’s yours, to use or waste as you like.
I think industry and commercial installations will follow this same logic to the same conclusion. And the greed of the electric utilities will ultimately be their downfall. ALL the great corporations of the past have gone the same way. It wasn’t the disruptive technology that got them. It was the hubris and the failure to adapt.
If they embraced the technology, helped people finance and install grid sharing solar systems and taken the same 30% markup everyone in the world deals with in everything, or even the 3% markup of the grocery store, they would have done fine and we would have a marvelously flexible and intelligent national grid. They would make a fortune just billing and paying people and clearing the economics of the market, and acting as tax collector for the government. They could even be in the solar equipment business. Instead, they will be selling off their office furniture at 6 cents on the dollar. Bucket trucks will be $1000 apiece. And the huge tax revenues generated currently will dry up like leaves autumn. Oh well. It is ever so.
For individuals, the selfish solar system is the future. EV components will power it. And for the present, it will be very very modular – the all-in-one boxes trying to be all things to all people will not make it.
66 thoughts on “Selfishly Solar”
But what do you do with excess solar energy?
Ultimately (and I think the tesla wall is aiming for this) if we will have a distributed generation and storage system, the utility networks will welcome distributed bi-directional storage. It reduces the network load and resolves the solar generation/usage issue.
The other big problem with your proposal is cost. Do you really need a 50KW inverter? I don’t think it makes a lot of sense to have a higher inverter capability than your solar grid can provide. Stay grid-tied, install a relay so you can go off-grid if it goes down, when it does go down just limit your usage to ~3kw, ie don’t run electric heaters/coolers. Because how often does that happen?
Hopefully the regulations will get better for solar/storage installations, because it’s in everyone’s interest.
Jack – another interesting, well thought out solution. Assuming the worst case scenario from the utility companies, which is the most likely scenario
Jerrod, I think you may have missed the point. The excess solar is not sold. It is yours to waste, and you don’t have to ask anyone permission to sell it or buy a bunch of hardware to comply with their silly regulations that change at a whim. Your house does not look like it has solar. It’s just a 200 amp service running a battery charger, on the off chance that your solar installation is too small to do it on your own. I read 20 KW as the size, but 50 KW would replace your 200 amp service at 240V single phase. Anything you could run with a 200 amp utility service, you can still run. And if you find you have excess electricity, you can move your home heating from natural gas or oil or whatever. Perhaps you can run a second electric car. Your imagination is your limit.
Jack – my only modification would be a bit of redundancy. If your chinese inverters could load-share, perhaps 2 of a 10 – 15 KVa inverter would be marginally more reliable although more expensive. Same with the battery charger – 2 x 10 KW tesla charger is a bit wasteful, but overkill is always appropriate?
It is indeed Michael. And two of everything would not be crazy. That IS the rationale behind keeping it very modular with very SIMPLE generic devices that instead of trying to be all things to all people at all times, with 120 menu configuration items on a tiny screen in inexplicable abbreviations. The SYSTEM becomes more flexible as the DEVICES become LESS flexible. We move the brains to the battery, and everything else just comes on or goes off as it is told.
This blog seems short and simple. It kind of is so by design. That’s because we are talking about a RADICAL departure from very ingrained thinking about solar that has evolved over decades. Batteries were adjuncts. Now they are the central issue. Tying to the grid was mantra. Here it is actually optional even with one in the room. There were TWO camps: grid and off-grid. Now, no real difference. Utility grid – generator, who cares? Selfish solar.
Over production of electricity? A couple of subtle things here. By massively oversizing battery, compared to what is done now, we widen the use range. In theory, the battery is never filled, and never emptied, and the operating “band” here is now 80 kWh, or perhaps 160 kWh. So daily variations in demand and solar insolence are absorbed in the bandwidth. But yes, Jarrod, if you find yourself with your battery completely full, and your current needs met, you simply switch off the MPPT charge controller, and selfishly let the sun shine on your roof without production. We cease to CARE about what time industry needs solar, what time homeowners need solar, or what the utility grid needs. We just make our own electricity and tend to our own knittin’. Selfish Solar.
Also radical is the departure in component technology. I was EXCITED about the new Outback Skybox and the Midnight Engineering B17. I WOULD be. I’m the ultimate tech gadget guy who loves EVERY shiny new bauble under the Christmas tree. But WHY are these exciting? They combine functions into a single box in a vain attempt to be all things to all people at all times, with then hopelessly complex configuration options. It’s like putting your TV and turntable and radio, and tape player and all that into one single box with an up arrow and a down arrow to control it all. And it dawned on me in a moment of epiphany that this is all in the WRONG direction.
We need to reuse commonly available devices remnant from wrecked EVs where we can, and control them with ON and OFF. And we need a slight modification to existing solar devices to actually make them EASIER to manufacture and use by going to a common 300-400vdc bus. That is much CLOSER to our native 240vac rms. The components become smaller and less expensive. And they don’t need to support 18 different battery systems because they don’t need to worry about that at all. They need to do what they are told, which is to turn ON or turn OFF. The brains dealing with what type of battery it is come with the BATTERY itself. It becomes the brains. And just like EV’s, it is one more time all about the batteries.
But the central theme in this radical departure is to quit worrying about the grid and the Pollyanna of shared distributed energy. It is an optional connection, and it is one way. You supplement your system through a common EV onboard charge device. And forget constant current/constant voltage taper curves. We’re not driving it anywhere. The battery controller turns it ON or OFF as needed at full power as part of an ongoing quest to keep that battery in the middle of its range. If it comes on too often, we add another string of 8 panels.
Going to a “sunny island”??? Replace grid with generator. And it will get but slight use.
I am touched by the intent on all the advice. But yes, I understand about 240 split phase and 240. I assumed you all know I put in a 15kW photovoltaic array, battery backed up, grid-tied, and net metered, as one of the first net metered homes in Colorado in 1998. This little system (by today’s standards) was the largest residential photovoltaic array in the world then, at a cost of about $275,000. And EVTV sports 38kW of panels on the roof today. I really do NOT understand all the complexities of the configuration of the Sunny Island. Indeed it seems mystical to me, which is part of the epiphany. If it is simply too complex for me to configure it, what has this techology come to? But I AM vaguely familiar with solar energy.
At the heart, grid-tie and reliable backup are mutually exclusive missions. Our 25kW Renosolar system is designed, and I suspect somewhat deliberately, to go out if the grid goes out and it is actually a bit complicated to marry it with stuff to make it work if the grid does go out. All to sell a handful of kilowatts back to a utility system at 1.75 cents per kWh. Forget it. The vision was laudable. But as the utility companies escalate what WILL BE a war on their own customers, we have to let it go. We have to separate the saucer section number one. Engage.
And that means supersize me. 5kw doesn’t cut it. 10kw doesn’t cut it. We can no longer just do “a little bit of solar.”
Well we differ in point of view. Ultimately I think the utility companies will bend you over a barrel and then take what they want from your pockets or otherwise at the first opportunity. And they are not above out right cash bribes to regulators and legislators to make that so.
As to the inverter, the cost is in the complexity. I think the Sunny Island is about $4500 and you need two to do 240vac at a combined power of 11400 watts. That’s $9000.
I am proposing a 20kw inverter that doesn’t do battery charging, grid coordination, nor feature 377 configuration parameters at $10,000. I was running the entire shop yesterday afternoon on about 3000 watts. Of course we weren’t charging any cars. But most of our wall chargers will do less than 10kw. So 20k seems right for a 14,500 sf industrial shop with electric garage doors, lifts, air conditioning, and EV chargers. That should cover any home. And I can see that 20kw device profitably on the market at under $5000 in quantity.
The key is to limit the intelligence in teh devices to managing what IT does and communicate on a bus. The battery controller should know all about the battery and how to charge it and simply send CAN requests to chargers and MPPT charge controllers to turn off and turn on and provide a specifed amount of current. Those devices should do what they are told and report that they have done so. The inverter should invert. It can report what the output load is and the voltage and the frequency if you like. Each device is somewhat “selfish” in this regard. It’s all about it. Component stereos instead of all-in-one devices. And each device should be installable and configurable by ordinary humanoids without a EE degree.
Anyway that is what we are going to work toward. Discrete devices. Heavy reuse of Electric Vehicle devices. And oversizing at will. Coordinated by CAN. Possibly a bluetooth interface for happy homo wner control and infotainment.
Yeah I suppose I’m talking about an idealistic future where the utilities are run for the community, not for profit. (or at least not wholly for profit) One of those situations where privatization and deregulation have backfired on us eh?
I understand the appeal of selfish solar. And I understand the limited appeal of feeding into the grid for less than the energy is ‘worth’ but isn’t the feed in far better rewarded during peak times? With a battery pack that big you could actually make some good money. And hopefully the utilities will figure out that this is good for them too and incentivise it further.
On reusing EV components.. It’s remarkable how similar a motor inverter is to a 240V 60hz inverter.. actually it’s mostly software. plus some output filtering. the half-bridge topology is identical.
Run a dumb sine wave encoded PWM through a tesla inverter, add a couple of beefy inductors, there is your 240VAC @ 300KW. Might want to wire up the current sensors to protect against overload.. This will require an ‘EE degree’ to get going though 😉
Other issue with a big DC/AC inverter is that low load efficiency won’t be good unless it has some trickery to get the low load efficiency up. If it’s bottom dollar Chinese, unlikely.
Another fun idea, wire your house to use HVDC instead.. Edison style. Most electronics convert straight to DC anyway! Do away with the big 60hz inverter. Switches wouldn’t work very well anymore though.. DC is also far more effective at stopping your heart.
I like your numbers Jack.
Although my situation may be unique, I doubt it, in fact it may be more of the norm for earlier adopters, especially for those looking to cut the grid tie. I live in the country, my entire house runs off electricity; lights, tv, fridge, heat/AC (geothermal), water and even my toilet. Being on our own well necessitates pumping our own water…so when the power goes out we have only the number of flushes left that the pressure tank can handle..about four.
We use on average 2000 KWhr’s per month, so a continuous average draw of about 2.7 kW. And I, even with multiple EV’s, am not the big user in my neighborhood; one neighbor with a finished basement and 5 sump pumps uses somewhere between 3500-4000 KWhr’s per month. In fact with the addition of our EV’s combined with household efficiency upgrades our average monthly usage has changed very little over the last nearly 20 years, only the geothermal made a noticeable increase while eliminating our reliance on expensive propane for heat…the net difference, the geo paid for itself within 8 years and our monthly power usage has averaged right around 2000 KWhr’s since we installed it in 1998.
So I don’t think your numbers are too low, in fact I may want a little more storage for my specific needs.
But I would still like to be grid tie for now. I belong to a power co-op, we don’t get paid for excess kW supplied to the grid but we do get to ‘bank’ them for up to four months. So I’m basically getting paid the same 11.4 cents per kWh in avoided costs/use.
It’s a variant of Net metering of which, like hybrid cars, there are probably many.
However my co-op does attempt to limit the amount of solar you can install to 20kw. They also want u to fill out all appropriate forms and get permission before installing; that latter part didn’t happen. So if I were to put up the approximate 25kw I wound need for cloudy winter days it looks like you’ve got the only game in town.
Well not only do I NOT have the only game in town, but there are far far too many games going on. And the complexity is frankly feeding a frenzy of fraud. Most people HAVE to have an installer put all this in. The FIRST bid we got for our rooftop solar was $110,000. The guy came down from St. Louis to deliver it and was all smiles and rubbing my back and just a really JOLLY kind of fellow.
I told him I was old and heavy and didn’t want to get up on the roof. And I would gladly pay $8000 or $10000 for the three days of work it would take to put 80 panels up there and wire them up. But the stuff was about $33,000 worth of equipment off of eBay, so make me smart on what costs $110,000????
Instead of answering my question, he didn’t miss a beat and told me NOT to order it on eBay. He did a LOT of volume and could get all that for me MUCH cheaper than eBay and would be happy to do so just to get his own volume up.
So I asked him again, if that’s the case, where does the $110,000 come up? He looked me right in the eye and told me “Jack you’d be surprised how many people just don’t know and don’t blink an eye at that number.”
EVTV just isn’t for the great unwashed masses. The length and boring videos are DESIGNED to make them go away. Leaving us with guys who can and do DO stuff and so are interested in the technical details. And I have ZERO problem with each and every one of them working eventually for profit and indeed a good profit. But 4x the cost of the equipment for a three day install with two guys? With the advent of an explosion in solar installations, come the usual bevy of fast dealers, montebancs, and opportunists. They are like locusts that land on any area of opportunity.
So I am proposing a simpler system using a voltage bus backbone common to electric vehicles so we can easily drop in their battery packs. Just like EVs, solar is eventually ALL about the battery. And I disagree strongly with JB Straubel that used batteries have no place in this. That’s EXACTLY where they are going to go and I’m not predicting anything here, it is already happening. But along with that I would propose simpler more dedicated function specific devices, with WIDER input and output tolerances, to make combining them in different ways simpler and easier. Selfish devices, in a Selfish solar design, to battle Selfish utility companies.
This would have the further side effect of demystifying all of this, making it difficult for opportunists such as my friend from St. Louis to play.
Straubel, et-al’s M.O. is to sell new. That’s were the money is (que Redwood Materials).
Jack, what are your thoughts on shifting focus to LEAF components? As they are arguably more plentiful, less loved and dirt cheap. Think of market value of a gen 1 LEAF this time next year and forward. Harvest the valuables, scrap the rest. I’d surmise they’d make perfect personal energy components. Hell, how about tapping in directly to the fast charge port (if equipped) as your 400 VDC bi-directional buss.
I think about shifting focus every moment of every day. When there is one of you, you have to pick your targets carefully. I think working on Nissan Leaf components would be perfect FOR YOU because you are interested in them.
I’m not. Tesla is the top of the heap. I haven’t got half of it done. And they are innovating faster than I can reverse engineer. I’m pedaling as fast as I can I tell you.
Grid Tie with Battery Back Up made Easy
Magnum Energy now has a complete grid tie battery based system by using the new MicroGT 500 micro inverters. Simply connect to inverters to a load panel along with the Magnum 4448PAE, add batteries and MagWeb and your basically done. Software allows you to monitor and choose when batteries charge or when to sell back and other features.
I love the Magnum 4448PAE. But we just had to purchase an additional “controller” for it just to extend the battery charging down to the voltage levels of our 48v Tesla battery module battery. This device started as a very simple and effective device to do a LOT of 240vac output in a very SMALL box, which is why it is the darling of your RV crowd. But this feature creep is precisely what I’m talking about, it becomes more complicated every day in the struggle to fill two mutually exclusive missions. Yes, you need more controllers. More software.
It is time to rethink it all, at least for the home. RV’s and boats remaining kind of a special case.
It’s kind of a case in point of what I’m talking about Larry. As you know, I love the Magnum PAE 48v and have featured it on the show more than once. But I had to purchase a remote control just to get it to accept lower voltages to take full advantage of our 48v pack.
I love the very IDEA of microinverters on the roof sending low current 240vac down thin wires to where I want to use them. But they are always too narrowly defined and limited in operation. The MicroGT is a case in point. It’s MAXIMUM voltage per panel is 55vdc. Two different panel manufacturers on my roof are BOTH higher voltage. The Panasonic HIT is 69.6 VOC and 57.6 MPPT. So I cannot use them AT ALL unless I want to match a panel to what this microinverter thinks is right and proper. And I don’t.
We are advocating truly STUPID and SELFISH devices, with very WIDE inputs and outputs. In this way, they can be combined easily to form the usual system, or the unusual one as the experimenter or designer imagines.
I had to buy an additional device just to get your Magnum PAE to do it’s MAIN job – invert, because it thinks it knows all about batteries. When indeed in fact, the knowledge base within Magnum Energy on the entire topic of batteries is actually extremely limited and prone to being outdated by new information. It thinks it wants to be a battery charger when it grows up. It doesn’t. It should rather aspire to doing what it’s told to do. Ideally over CAN.
Jack, be sure the Chinese build you a split phase 240 volt AC inverter, most Chinese inverters are 240 volt to ground. These units need a somewhat special transformer to get them to 240 volt split phase which is compatible with our Grid / house hold connections.
Excellent. This blog polished off some the rough edges of the position I’ve taken on this subject. The local utilities here have already started to countermove against what we know will happen, especially in Arizona and Nevada. Co-workers frequently ask if I’m buying a new Tesla. The answer is NO, but I will follow the prescription above. The two types of people that irk me just as much as a plaigizer irks Jack tend to say: “you need to……” and “Your gonna have to……”. I fully expect the entrenched money minions to show up after the system is working with a warrant trying to prove that I craped in their rice bowl.
When I lived in Alaska I bought one of those neat 6×6 amphibious Argo-like things. I lived right next to a lake with a huge network of trails all around it. I thought, Hell yeah! I can cruise the trails with a fishin’ pole and when I felt froggy, I’d just aim starboard and go snag me a nice bluegill. Well it didn’t really work out that way. It was an awful ATV. Seriously slow. No suspension. Loud. Hard to control. On the water it was no better. Painfully slow. Leaky. Loud. Hard to control. Skip to a few years ago when I bought my first hybrid car and a couple months ago when I bought the second. It’s only attribute is really good mileage but at a price. The car is slow and under powered. When the assist electric motor kicks in, it kind of keeps up with traffic after the light changes. It does handle very well and you can feel its lightness. Take out all the batteries and electric drive stuff, put some wider tires on it and a turbo-charged 4cyl with 200hp and you’d have a fantastic little sports car. Take out all the ICE crap and replace it with a 100kw magnetic drive system and you’d have an amazing EV!
These are just two personal examples. There are more. Flying cars are not good cars or good planes. The V22 Osprey is not a good helicopter or a good plane. I’m not sure what a platypus is good at.
Moral of the story is that anytime you try to make one thing do more than one thing, you end up with a thing that doesn’t do anything particularly well!
This is a fantastic concept, Jack! Let purpose built components do what they do. Battery chargers charge batteries. Solar controllers control solar. Inverters invert. It’s like the old-skool stereo systems. Pre-amp, amp, tuner, record player, reel-to-reel, equalizer…
Up front costs are going to be higher but if one component fails the whole system doesn’t go down. Problems are easily traced and everything is repairable or replaceable if it fails.
This is good!
Platypus is good at confusing people;
What to do with any excess generation? In summer, make ice… In winter,ahhh? takeup electroplating as a hobby…
I hadn’t addressed this as it seems to me obvious. But excess energy should always be used to heat water in my estimation.
You could always electrolyze water!
A few issues with that.
You need distilled water. Any impurities will clog up your expensive hydrolyzer.
Hydrolyzers tend to be 50 – 60% efficient at making hydrogen. And fuel cells tend to be 50 – 60% efficient at turning hydrogen into electricity. Which means your cycle efficiency (electricity -> hydrogen -> electricity) is in the 25 – 36% efficient range. Most batteries will give you 85% (or more) back.
How are you going to store the hydrogen? It’s the lightest element on the periodic table, so 3,000 psi into a storage tank holds less energy than the same tank, same pressure, filled with natural gas. It takes 14 liters of cryogenic, liquid hydrogen to match 1 gallon (3.785 liters) of gasoline; that’s about 4 : 1, volume-wise for something you CAN’T store in a stamped metal tank. Liquid hydrogen only makes sense if you pay a fortune / pound (spacecraft). Compressed hydrogen doesn’t really make sense at all, since you end up using a LOT of energy compressing it to insane pressures (Honda Clarity FCV uses 10,000 psi hydrogen; still lower energy density than cryogenic liquid).
Audi has facilities which use electricity from the grid (when renewable sources are outstripping demand; this happens in Germany) and turns CO2 + water -> hydrocarbons usable as diesel fuel (they call it e-diesel). And, of course, Audi has plenty of vehicles which will run on diesel. If the CO2 from the tailpipe <= CO2 removed from the environment to make the fuel, you have fuel which is at least carbon neutral.
I'd like to see one of THOSE, in small-scale, which can make a few gallons of diesel / week in my garage.
Hey Jack back in November I told you how three of the new Corporation Commission chairs had their ads backed by the parent company of one of our utility companies. So it is said that parent company has 4 out of 5 chairs in their pocket. But if you have been following the news a ex chair is under federal charges that he took bribes, and that this is just the tip here in Arizona. I like your selfish solar, but my first thought was like you to only have grid tie to charge up a set of batteries late at night during the time of least money per Kwh. And use two battery packs to run my house. One to run the house and the other is charged or waiting to be charged. I would then connect the second pack to the house and disconnect the spent pack and set it up to charge. This way the house always has power, I have less utility BS to deal with and they do not get it back. Yes I know that this at this time is way more expensive for the packs, I was hoping to get two Tesla powerpoles. Steven
The “play” here is the availability of largish battery packs from wrecked EVs. Large enough that you don’t need to swap anything. You operate in a “band” from 80% SOC to 20%SOC that buffers the variation in demand and solar insolence. The more you oversize it, the less you have to do or worry about.
I need not wax poetic about all the nefarious goings on of the utility commissions, state legislatures, and electric power utility corporations. You are going to hear all too much of that in coming months and years I do fear.
But Selfish Solar is much more of a radical departure than it first appears, and one of the central missions is to enable you, the individual, to survive them of the greedy grasp. The “selfish” is of course an ironic pun/twist on the utility companies themselves. It will be their undoing in the end. They are going to use pennies per kilowatt as a very effective controlling lever to coerce you into compliance. And you don’t need the pennies. But you have to let a core and key concept of the solar vision go. We have to separate the saucer section.
Not my first war I’m afraid. I’ve done this before. Hold my beer…
In farm country when the utilities buy right of way from individual farmers AFTER they’ve signed a non-disclosure agreement. Any attempt to collectively bargain with equal compensation for all is squashed with all the resources the utility can legally muster. The utilities may eventually find themselves in the uncomfortable position of negotiating excess power contracts with a collective solar farm owners co-op. Ain’t karma a bitch.
Yes Jack I understand. I am a number guy and bad with the words so I may not got what I was thinking across. There is no “swap” as I turn on one pack to take over the load while I turn off the contactors to set the other pack up to be charged. Thus if the line goes down there should be no back pull from the charging pack. Here in Arizona during the summer months I have an average of use of 46Kwh per day so if I went with a Tesla pack I would need a 100. Steven
I didn’t say Hi-Jack because I work in aviation and that phrase is verboten in these parts!
Here in Nebraska we have “public power” meaning not for profit publicly owned utilities.
My local utility charges $50.00 to install a new meter for a new customer. When I installed solar they charged me $75.00 to change out the existing meter to a bidirectional meter. Illegal by state statute but nobody will enforce it. They also got the utility commission to approve a “customer fee” which is similar to the connection fee you mention, at the amount of $17.50 per month. Plus buried in the rate schedule is a “minimum bill” of $35.00. Here is how it works, for example if my solar array generates100KWHrs more than I use in a billing month. The utility charges me $17.50 customer fee plus another charge labeled minimum bill of $17.50. So far I have a bill of 35.00 and have used zero electricity from the grid. In fact I have provided 100KWHrs TO the grid which my neighbor used and was billed 10 cents per KWHr for. Total income for the utility so far is $45.00 plus taxes of course. Wait, you say they have to pay me “avoided cost” by federal law. Yes, that is true, I get about 5 cents per KWHr so they give me $5.00 off my $35.00 bill, so the utilities net income in this example for providing zero electricity is $40.00 per month. That is sure to encourage more customers to add solar – NOT!
Nebraska also joined the lawsuit against the federal government over coal power plant emissions standards AND charges electric vehicle owners an extra $75.00 per year fee on vehicle registration because they don’t burn gas.
You are on the right track. Keep up the good work. Every new paradigm is expensive at first. Most early adopters are called uncomplimentary names until they turn out to be heroes later. Often much later. I’m glad you are out there with the resources to show what is possible.
Does an EV conversion need be registered as an EV conversion? From the exterior it still resembles a non-EV, hence you’re $75 richer per annum
If you think I am overstating the case of the complexity these devices have achieved in their quest for grid compatibility, I just did a count of some of the basics of our Sunny Island 6048 US.
It has 377 individual parameters with as many as 14 options each.
It reports 82 events
And it issues 202 different warnings or cautions.
AFTER we have our CAN communications perfect with all required messages operational, you have to have EXACTLY the right set of parameters entered for it to actually charge the battery.
It has reached what I think of as “hopelessly complex”. You have to have a professional installer put it in and most of them can do about 3 variations on a system in their repertoir and have memorized the settings for those three basic installations. Any variation sends THEM back to a comically inept piece of technical writing – the installation manual. It is richly detailed and largely devoid of any useful information.
We requested some advice from the manufacturer in Germany and were advised to sign a non-disclosure and they would get back to us within four weeks.
I would reduce the INVERTER part of our diagram to doing one task. If it receives DC voltage in that is within its designed range, it puts AC power out the other. The configuration should be how = the voltage, frequency, and number of phases. Multiple units should be able to communicate to link their frequencies, and phases and share load among them. NOTHING about the grid. NOTHING about battery charging, and nothing about PV. If it gets 300-400vdc on the “in” side that’s all it has to know. And limiting it to that you are still going to have 20 or 30 configuration options. But not 377.
Similarly the MPPT charge controller. Why does it need to know ANYTHING about batteries. It ought to turn on and do the MPPT thing when the battery freakin TELLS it to. FLA/VLA/GEL/LITHIUM bulk, absorption, float, equalization? fuggetaboutit. It should turn on and provide exactly the amount of current the battery tells it – up to what it is able. Given what solar panels do, it should have a VERY wide input range – from 0 to 600v. And a much narrower output range 300-400v. And that’s the gig.
I like what you propose
Its sort of like the pika energy island
It has a 300vdc bus and you hook battery, pv via optimizers and inverter to it.
Im pretty fluent in sunny island programing but i always have to read the manual as i set it up.
I have memory cards that i pre configured for the common installations
Wait till you see my outback setup
With midnight charge controllers
Way more crap on the wall than an ac coupled sunny island
Well of course that’s the payoff and I do get it. Reducing component count always looks good on the wall. A Zenith color tv with built in radio receiver, turntable, cassette player, and coffee maker is too. But they ultimately wound up mostly acting as furniture, a TV stand for a newer television.
Whereas component stereo systems were all over the room or required their own set of bookshelves just to hold the SEPARATE reel-to-reel, casette, turntable, radio receiver, power amplifier, etc. But the modular approach was much more flexible, and you could upgrade a single compnent or add a new one (Sirius radio) without major alterations. And everyone quickly became familiar with the gazintas and gazouttas of stereo. You plugged one device into AUX1 and another into AUX2 and so forth. Easy to configure. Easy to operate. Easy to update/upgrade a piece at a time.
And that’s where we are in Solar at the moment. Tesla’s powerwall will do the charge control, the inversion, and the battery all in one box. It will also purportedly play nicely with the grid though I really don’t understand how they have all that worked out given the bewildering mix of tarriffs and time of day charge variations and so forth.
It will do 10kW in a $12k device. And I expect it to be popular among the unwashed. But it’s doubtful if our viewers will find it satisfying in the end. Too opaque. Like a Zenith, you have to replace the whole thing just to get the one you really want later. And too expensive.
My belief is that we’ve gotten out a little over our skis. The solar technology is NOT mature and is rapidly developing and improving. And so you are going to want to have access to those new toys. So they should be modular and plug compatible. We haven’t even settled on voltages yet.
And I may be in a little over MY skies there. I’m very used to 300-400v and don’t consider it an electrocution hazard in the least. More a fire/heat/burn hazard from dropped tools and metal frame sunglasses. But that’s because we NEVER ground our battery systems. In solar power, I suppose you kind of HAVE to ground it at some point. And that makes the higher voltages much more dangerous. I do NOT agree that DC is more dangerous than AC and indeed the opposite – going back to Tesla/Edison battle over AC/DC. But despite wearing Crocs 100% of the time, I still don’t want to grab 400v with a path to ground, particularly not through me.
“And I knew, and THEY KNEW that I knew” … that there wasn’t a DAMN thing THEY could do about MY Selfish Solar System.
That goes back a way. Yes. Precisely so.
The utility companies know their bottom-lines are on the line.
Nutshell: solar is getting cheap enough that, increasingly, people can afford to load up on solar panels, batteries, inverters and go completely off the grid. Which means that fewer and fewer people will be subsidizing the grid. Which means that the rates for each will need to go up to keep providing profits. Which means that solar and going off-grid, to avoid the ever-increasing rates, will become evermore attractive.
It was a utility industry trade group which came up with the report. In 2013.
There is a whole COTTAGE INDUSTRY of consultants like this with sky is falling scenarios and the Utility Industry right now is paying them very well for such reports. The recommendation is always the same – convince regulators to let you charge more money and all will be well.
Disruptive technologies are disruptive. And the adoption curve is cruel. It isn’t a problem for a long time, and then suddenly a third of the customer base is making their OWN electricity and you’re business model is cratered.
This report ironically uses AT&T as an example, casualty of one of my earlier rodeos. Land line and Internet was lost to them but they morphed into a cellular company to survive.
Similarly, in a perfect world, Utility companies should be designing and selling, and indeed leasing fully interoperable equipment TO homeowners much as Solar City was doing. In this way, they could very productively manage the grid and power production right down to the cellphone charger plug. They could profit from equipment sales and leasing. And ultimately their profitable role is as tax collector market maker in the economics of electrical power production and transport. In this way, larger PV operators could profit as partners. And the utility company could be out of the power “production” business entirely. Almost 100% of the new plant installed in the last 20 years of ALL kinds, mostly natural gas, has been outside companies that sell TO the utilities ANYWAY.
But it isn’t going to happen. Burlington Northern railroad had all the metal shops and engineers necessary to design and build the DC-3 aircraft. But it didn’t happen that way and it never does. Hubris. Arrogance. And greed. Utility companies as we know them are headed for a “Kodak Moment” and in the end, will have only themselves to blame. While Kodak was busy stealing from Polaroid and wrangling over the patent issues (which they lost by the way) someone invented digital cameras. Which were way too expensive and didn’t produce sufficient quality for “professional work.” Kodak declared bankruptcy in 2012 by the way after over a hundred years as the bluest of the blue chip stocks.
It’s kind of why you never see pachyderms entered in the Kentucky Derby. They are of course bigger and stronger, which counts for something. But it doesn’t count for everything.
SMA 6048 is a bi-directional inverter I thought? Need midnite solar or sma transformer to get 240 after that just connect sunnyboy to output of 6048? can it charge doing this?
Jack, I got a spare REC solar bms that talks to the 6048 if you would like me to loan it to you or I can do some can capture on in a few days.
Thanks. I could certainly use a CAN capture. I think we have it worked out and did indeed get it to charge batteries from a grid input yesterday afternoon finally. But it would be great to look at a CAN capture from this device. Send to email@example.com
Again thank you.
$52,000 = installation cost! 🙂
Some bit of an update. I had been enthusiastic over the Morning Star MPPT 600v charge controller we installed. Wide input range, and wide outputt range. This device has JUST come on the market.
But of course, they have settings for forty eleven bajillion different battery combinations, of course none of them ours. So it kept going into float, or absorption or bulk or equalization at random. It will do 60 amps, but we’re routinely getting 35 because we never actually set it up.
It has a “custom” function where you can define all that yourself.
I was very displeased that it requires you to use THEIR software and it is ONLY available for Windoze… Bad move number one.
But I asked Dylan to look into it and set it to just charge at max all the time, in all phases, in a custom setup. He chased down an ancient Windoze machine and attempted to do so.
The next thing I know, he is on to customer service at Morning Star and he asks me if I know what a “crossover” ethernet cable is. I assured him that while I did, it was perfectly understandable that he didn’t and further that the guy at Morning Star must be mistaken. We haven’t needed a crossover cable in 20 years. I went on to explain why this had been SUCH an issue back in the day (before his birth) and how it was finally solved with MDI-X in the early 1990s such that ALL ethernet circuitry thereafter automatically negotiated the tx/rx quite flexibly. And so crossover cables simply weren’t necessary anymore and you would never find one.
It looks like we’ll have to make one. You CAN configure it wirelessly, but only after you get on with the crossover cable and set up the wireless configuration of course.
This is incredibly backward. This device has only been available for a couple of months. It’s a brand new design. And somehow SOMEWHERE they found an ethernet chipset that does NOT do MDI-X. WHY?????
Again, all this thing does, or should do, is MPPT tracking of the PV array and put out current/power to a battery. Why they imagine they would know anything about what battery is just stupifying. All we need is a way to turn it off and on. But it is totally CAN deaf. They should at LEAST provide a 12v input to “enable” or “disable” or something but no. Nothing like that. Just 79 different battery chemistry configuations, and of course none of them ours. And we can’t do the custom configuration until we BUILD a crossover ethernet cable. It is so backward it is beyond belief. And this is the industries “latest and greatest.”
I really think the solar equipment
vendors have gone entirely the wrong direction, and I’m starting to see why.
Wow….. Love your stuff Jack, I just can’t get over how bassackwards some companies/industties/people can be…. Wow!
Somewhere out there Jack just got the boss’s nephew fired.
I wish that I had known you needed a crossover cable when I visited last week… I had a couple of crossover adapters in my toolkit that I find useful on rare occasions. I bought some a few years ago at a local shop, but amazon has some similar ones. https://smile.amazon.com/dp/B00N07LDF6/
I was nice to meet you and the wife and I enjoyed the visit. Stan goes back to BOARDWATCH days and continues with EVTV. Enroute to Indiana, he stopped for a chat the other afternoon and we relived some of the early days.
Which is where CROSSOVER ETHERNETS BELONG!!!
You have stumbled onto the primary reason that I do not recommend any Morningstar charge controllers. They are so antiquated in their approach to programming I turned away from them over a decade ago. If you do have a Windoz box and an DB9 RS-232 cable, and download their 1990’s software and somehow get it all talking, then you can program all the customs settings. My question is WHY? No other respectable manufacturers are building MPPT controllers that require this nonsense.
Morningstar did come out with the Prostar MPPT controller that can be programmed from an optional meter panel but all other models should be avoided if you need to make any custom changes, and most batteries need that.
Starlight Solar Power Systems
If you can get your “Selfish Solar” system can also be placed on a 5’x8′ trailer with a good price, I might buy it.
Strike the “can also be”.
Well, we certainly could – except for the PV panels of course.
If you also made the grid plug-in be a 50 amp 15-50 RV plug, then you can easily sell this as an AC/DC system for RVs. I need something like this for a tiny house that I am building.
It would take a tiny house to hold the battery and equipment.
I am advocating we go to BIG solar and SELFISH solar for grid independence. So you would need a tiny house to house your solar, and the other tiny house to be a house.
Yes, a 5’x8′ trailer would be a very small tiny house, but if the battery and inverter can be installed and the roof can have a few solar panels as well. But am I not saying that Selfish Solar Systems have a particular size, and can be mobile. By the way, most modern houses use 200 A electric panel for grid connection. So, the inverter needs to be 200A x 240V = 48kW, not the smaller 20kW you state in the illustration. Because the 240 VAC is lower than 400 VDC transforming the power should be easier.
Most modern houses do have a 200 amp service. And some have 100 amp. And some 50 amp. And quite a few 400A. The service entrance has nothing to do with how much power you USE. It has to do with how much power you CAN use.
I would say 20kW handles most homes nicely as a peak. You will rarely see a backup generator even that size – most are 10, 12, or 15 kw. In any event, you can have any size inverter you want. The idea is to remove charge control from it and the convoluted gyrations they currently go through to handle the dyslexia of being ON grid, OFF grid, and kind of on grid all at the same time. Islanding and non-islanding and so forth. It is madness. I would advocate they be much simpler and convert 400vdd into AC appropriate to the locale and installed appliances. In Europe, mostly 3-phase. Here, two phase 240vac. And focus on the ability to modularly expand them and have them work together to stay on phase and frequency with each other, not the grid. In this way you could have any number of them to make up what power you need.
Brilliant article. Exactly the situation we are facing in Australia as our energy industry tries to shore up its outdated business as usual case. If they got off their butts and offered us up to date production practices at realistic prices, we would all happily stay connected to their grid. Instead they try to shut us down, overcharge us or legislate us out of existence.
Finally found time to read this post. As usual, a great read and most intriguing in part and rather stimulating. And note, not a word on climate change or floating icebergs up the Mississippi.
The idea of a common 400V dc bus for EV and solar components is the way to go and will probably end up as a standard pretty soon. But inverter, battery pack and charge controllers manufacturers have to agree standards for interconnect and a control bus. Note that the solar inverter market is not famous for standardization. Help might be needed from IEEE and such bodies.
A word of caution with Jacks setup though. A tesla charger charging a tesla battery pack, speaking elonian CAN language is pretty safe. You should be able to draw power from the HV bus of that system safely as I cannot see you doing a Ludicrous Mode discharge in normal use (okay yes you can – with a short circuit ; – )). However once you throw an external non elonian charge source on the HV bus, we are in new territory. Some will say the external solar charger will also speak elonian CAN, but …. (shrug).
I submit that the safest way to charge the tesla pack by solar, is to first convert it to 230v ac and then use the tesla charger to charge the pack in native elonian CAN language.
Your word of caution is ill informed. We are not going to use a Tesla charger to charge the battery by using the native Elonian CAN. We have replaced control of the battery pack with an intermediary controller with its own CAN and contactors. It DOES talk to the battery pack in ELonian CAN. But nothing else need to.
And it IS the control. It would control the Tesla charger, AND the solar MPPT charge controller. In other words, the brains for what the battery needs are in the BATTERY. The brains for what the MPPT controller needs are in the MPPT controller. Etc.
We are provisioning the battery controller to use CAN, switched 12v, and switched ground signal outputs to control other devices as they are able to respond. We just added CAN for the Sunny Island inverter for example, but the Morningstar MPPT is an idiot device already and we open and close a contactor to apply the HV to the charge controller.
Similarly the grid ot bus charger would simply be on or off. In the case of a Tesla charger, I can probably do that by CAN.
But yes, a standardized control interface is very much a needed concept and I would of course advocate CAN as the lingua franca because I’m familiar with it. So yes, 400vdc common power bus and CAN common control bus would be nice.
There are ways of combining data with power. I have never liked nor trusted them. But they would simplify the wiring immensely.
IEEE “help” will be found to be #1 slow, and #2 unavailable. The members pay dues and you need to pay just to get anything from them. The rub is it’s a club composed of rice bowl guarders that will see all this as a threat to their planned early cushy retirement. The players in that club will see no reason to support the enemy. They will SHOUT safety and be patting themselves on the back for protecting you from yourself.
In a word…. Brilliant! In the process of moving to our farm. The house, it will be on the grid (of course that can change). The barn, well, if I can build it out in a modular fashion…. Off Grid.
Eagerly watching your success in building out the ‘boxes’.
I must say all this stuff, is getting me enthused to go all electric on my own. But if you don’t mind, I would like to ask. Does the battery box fit on the Yellow Rubber Doka bed with the sides up? And are you getting extreme range from the new pack? I know, way too many questions. V/R.
Good logic, Jack and a good video from Tony. Much appreciated.
Hi Jack and Bill,
Sorry to hear that you are leaving the show Bill. I know from watching you work that Jack’s loss will be someone else’s gain.
Jack thanks for the new videos. A double feature no less. I especially enjoyed the clips of the Cadillac being fitted for the Tesla drive line. You may have a new Alabama TV star in the making.
I work in the solar and off grid industry and have thought about a higher voltage dc system before. I did a quick search and I see there are 380v dc bus systems available, for e.g a company called starline. I’m also aware that LG chem have 400v battery storage unit available that can interact with a few inverters. I’m based in Australia so not sure what is available at 60hz for US power systems.
As an aside, my off grid work led me to a battery charger called the Victron Phoenix which can operate off ac or up to 400v dc to charge 12 or 24v batteries. They might be a cheaper choice than dc to dc Converters in evs?
I love this idea, the only suggestion I would make is a smaller charger, or maybe multiple smaller chargers you could switch in as needed. In the western US demand based charges are common for commercial customers and will be coming to residential soon. That is, the amount you pay for electricity is based on the highest demand in KW that you have that month (i.e a business with their highest demand being 50kw will pay more than a business with their highest demand being 10kw for the same amount of electricity). The charger really needs to only be large enough to meet the 24 hour demand plus a little extra to start to fill the storage batteries back up. We had a hot month in July and I used a lot of power, approximately 50kw per day. If I run the charger 24 hours a day a 2.5kw will easily meet my daily need with no solar so why charge faster and have a higher peak demand. If you do that you can still meet your daily needs while minimizing the amount you have to give to the utility for peak demand fees.
With the new time-of-day rates that both SRP and APS are going to in the Phoenix metro-plex one would size the charger so that charging would only occur between 9PM and 11 AM. The comment above is valid in that one should manage a peak usage as low as possible but also take advantage of time-of-day rate breaks.
Here in Missouri, we are actually PRECLUDED from using time of day rates if we have solar.
As soon as I get back to Arizona I’m switching to the time-of-day plan they’ve been hounding me to go to before they catch on. Without a grid-tie, the golden handcuffs are more or less severed and THIER hidden agenda selfish arguments don’t apply. I’ve been laid off many times. I’ve never met anyone laid off from the utilities, big pharma, or health insurance companies. Must be nice.
I read this article with a lot of interest. Your portrayal of a “selfish solar” system is exactly what we see emerging in Europe where the feed-in tariff has been steadily ratcheted back and those with solar have moved to putting in batteries and/or timing their use of electricity to when the sun is shining. And all of this makes sense!
I do want to push back a bit on the part of utilities though. You, and I dare say most Americans, do not know that 25% of Americans buy their electric power at cost. That’s right. Cost. No markup, no profit, and for the most part no regulators. They are part of their local electric cooperative. These electric distribution co-ops are owned by their members and have a simple goal, to provide power as safely, reliably and cheaply (and increasingly as environmentally responsibly) as possible. Here is the interesting thing, their prices are not terribly different than the investor owned utilities. I believe that nationally they are just 18% lower. Some places they are on a par or slightly higher than the IOUs, of course they have a LOT more miles of line to maintain. In fact they co-ops provide the distribution grid to 78% of the landmass of the US!
So, if it is at cost, why are they not cheaper? The reason is that it costs a lot of money to maintain that huge system of poles, wires, transformers, voltage regulators, sub-stations and the like. In addition, those pesky line-men want to get paid. So does the person that answers your call when you ring up the utility, and the person that ensures that your bill is correct and that your payment is credited to your account. Most of these costs are the same if the distribution grid delivers 100kWh of power in a given month or 40,000kWh! In fact, for most co-ops in the US, the true fixed cost of operating the grid is on the order of $45 per house. Some a LOT more, some a bit less. So the $150 asked for in AZ does feel a bit off, but neither should your fixed cost be just $12 as it is in many, many locations!
Then there is the question of how much a solar array owner should be compensated for a kWh put back into the system. Federal law says that they must be compensated at least the avoided cost. Without going into too much detail, what that means is what would it have cost the utility to go out and buy that kWh on the market? And the sad truth is that the wholesale cost of electricity is pretty darn low. $0.0175 is on the very lower end, but not surprising in a place that has a lot of coal burning power plants. These cannot be ramped up or down except over very long time frames so the costs are very low. (Coal power is typically bid into the power market at $0, and then they get whatever the highest amount that needed to be paid to cover the total amount of power needed in the market a during that time window.) The utility company, within bounds has the option to buy their power wherever they can get it cheapest, so they could buy that kWh from someone with rooftop solar or from a large solar developer (who typically sells at $0.035 to $0.55 depending on region)or from someone with a coal fired power plant. Should they pay more for the solar power? In most places they can buy solar energy from large developers for about 2 cents more than from fossil-fuel energy sources. So should they pay more for a homeowner’s rooftop solar energy? Well, yes, but again, within limits. Producing the power locally and not suffering transmission losses is worth something, so is being kinder to the environment, so is reducing our dependence on foreign oil, etc. The question becomes, just how much more should the utility company pay for clean, green solar power and shouldn’t they buy that at the cheapest possible price? Just how much should they pay for the output of a rooftop system?
The answer may be that most Americans think it should be very little indeed. Remember again that electric co-ops are wholly owned by their members and they meet at least annually and can make choices about what their utility should do and how much they are willing to pay for cleaner, greener power. The sad truth is that most co-op members across America won’t spend even $0.02 more per kWh for clean, green solar energy. Remember, this is at a utility run by its customers. People choose low price again and again (which explains Walmart, etc.)
Finally, I encourage you to think on what might happen to the distribution grid is huge numbers of people put in selfish solar arrays. If the local power company does not sell and kWh then they have to roll ALL their fixed costs of operation into the connection charge, not because they are greedy, just because people still want to have a grid to connect to. Otherwise EVERYONE has to have their own solar plus storage system, everyone has to be their own utility! And everyone can’t. They don’t have the funds, or the credit score, or they don’t own their roof, or their roof is not aligned correctly, or is shaded or, or, or… Maybe they could band together into groups and let those that can put in such systems provide for others who would pay them for the service…wait, that begins to look like a utility again!
I agree with you, selfish solar is the way to go, I plan on doing so myself, but it is not a model that is expandable to provide power to everyone, and certainly not for less than the utilities charge.
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I have been reading all these comments, and had to comment about the rise of “complexity” of devices and the need for more “dumb” devices.
One of the bigger reasons devices are getting so complex is that they do not talk to each other and use more proprietary communication, even the ones that do use CAN does not mean they are compatible. There simply isn’t any common communication standard for electrical components for these setups
This means that the MPPT controller will not nessesarily know or be able to talk to the battery and therefore has to act independently and be programmable to charge anything from a lead acid to the multiple chemistries of lithium. With lithium a prism cell, Tesla module, and volt or leaf modules all have different charge parameters and different options like heating/cooling.
If there was a standard for CAN communication, the battery’s with BMS systems could control everything. That standard should also be open source, as closed standards like NMEA2k quickly were overwhelmed by the faster pace of technology, and the beurocratic way they do business makes adding to that standard difficult and time consuming, and prohibitive for small companies developing products to even get into the game.
I recommend you look at victron energy’s “Venus” system and CCGX display. These are open source with what looks to be a pretty vibrant development community. The devices control everything and can be set up for selfish solar, grid tie interconnection, or sell solar and battery power into the grid at peak, and charge back up with cheaper off peak grid electricity. I personally love the display as it really gives me a simple but informative picture of what’s going in my grid
Speaking of which is your EVTV Tesla BMS controller compatible with the Victron CAN bus? Using the Tesla modules unmodified using your BMS would be easier and less complicated, otherwise I will have to use the REC BMS which is compatible, but cost more and I will have to remove the module BMS boards and connect to the voltage and temp wires of the pack.
My system is for a boat, and have to consider many of the same issues you are concerned with in this post. Marina shorepower is considerably more expensive than at a house. I need to store as much power as I can, to operate away from the marina, I will be getting power from the grid, solar, wind, hydro generator, diesel generator. If my batteries are full I want them to communicate so excess solar/wind go into heating or making water. And unfortunately my shore power is not guaranteed to have the same voltage coming in, could be 104, 115, 208, 220, 230, or 240. I’m using Victron inverter/charger as it will boost power if I get 104/208, can limit power coming from shorepower so I don’t go over 25/30 amps, and can boost power from shore power or a generator for high loads or starting loads. I can manually reduce the shore power, to take advantage of the daily solar input and reduce the use of expensive marina power, or with the CCGX/Venus controllers It can automatically manage all of the power and adapt to the daily power input situation.
My shore power inlet is complicated but parts are useful to house systems as it balances the loads for L1 and L2, allowing full use of power without blowing breakers from using too much of one side of the 115 buss. Shore power comes in to the boat to a Victron automatic isolation transformer. This sepetayes my power sytem from the shore power system and takes a 115 or 230/250 inlet, automatically forcing 240 out. From that outlet I take L1 and L2 (not neutral) into a Victron autotransformer which gives me L1, L2, and floating neutral. At this point everything on L1 and L2 shares the load so I don’t pop breakers as long as the total load is less/equal to the shorepower supply. 30 or 50 amps in my case. L1 & L2 come off the auto transformer into a Victron Quattro 5kw combo inverter/ 48v charger, a 230v Euro model that has to be programmed for 240v American power before use. (I could also use 2 3kw combis and program them to interoperate as 240v single phase) from the combi power now enter my breaker panel where i use 240v for water heater, watermaker, and dive compressor, and I use the two legs for seperate 120v systems. This allows me to use power up to my shorepower inlet maximum regardless of which 115 circuit is using the most power without blowing those breakers. Example if my coffee maker is going and the girlfriend uses the blow dryer using a plug on the same side it won’t over load that side. The nice thing about the Victron combi’s is that I can boost and suppliment the shore power if I need it. Say GF turns on a 25amp blow dryer, and doesn’t realize that the coffee pot and say the instapot are both on. a total of let’s say 40 amps total with the blow dryer. This would blow my breaker on a 30amp shorepower. The Victron will pull that extra 10 amps from the battery untill the power use spike is over and dropped below 30 amps again.