100kWh Tesla Power Wall on Steroids. The PowerSafe 100.

We have drawn no small interest in our SELFISH SOLAR initiative – indicating everybody knows there is something wrong with the devolving net metering situation across the land. And this week’s video takes a deep dive into Selfish Solar. It may get a little technical. So set your Life Alerts on STUN and cinch up your Depends old guys. We’re going in….

As you can see from the recent AmerenUE bill I used 1140 kWh in this period. That normally would have billed $94.96. But I offset it with solar and indeed generated 1597 kWh for a 457kWh surplus. But at $0.0247 per kWh “avoided production cost” that generated an income of $11.29, just barely offsetting my basic connection charge of $11.24. Interestingly, even though I DID offset that connection charge, they still collected taxes on it as if I did not – $1.48 leaving me with a net bill of $1.43.

My point is, this is a rigged game. And it is rigged against YOU. In every way. In large ways. In small ways. Indeed it is the small, sly picayune elements that annoy me the most. They never miss a trick. Taxes on charges you didn’t incurr????

But beyond that, the bigger point is that the polyanna kumbayah concept of investing $100,000 in your roof and using it to generate income from the utility company never was going to happen. And your attachment to that vision is being used against you.

Rather, I would advocate, just pay the damn $11.24 for a BACKUP connection from the grid, and don’t bother with exporting power at all. Generate your own electricity right where you consume it. Store the excess for use at night or during inclement weather. And tap the grid when you need to during extended periods of bad weather or if your system goes down for parts.

But most of the comments we receive on selfish solar are some variation of “just do this and you would STILL be able to export power to the grid.” That rather misses the point. We’re trying NOT to deal with that at all. You just won’t give up the vision. And they will and do use that to control you.

Battery storage of solar electric makes no economic sense at all at the moment. We are spending huge amounts to demonstrate nonsense here. But that’s where I live. What I know is that at some point it will make very good economic sense to do so. If the technology and tribal knowledge is there to do so.

Everything changes. The world is in a state of constant flux. Here’s some good news. At the end of 2016 lighting consumed 25% of our TOTAL electrical use in the United States. And at that point, 88% of ALL lighting in the U.S. was STILL incandescent bulb. In this video I mentioned that we just bought an LED fixture that gets 133 lumens per watt. Indeed, LED lighting uses about 11.5% of the energy of incandescent for exactly the same light.

And the light has gotten better. I can get LED light now down to 2700K temperature (warmish yellow light) instead of the harsh blue white light the early bulbs gave off. And last week I bought 8 of GE’s latest vibrant color LED bulbs that look very much now like an ordinary 60 watt incandescent bulb for $24.95. That’s a little over $3 a bulb.

And so as late as 2016, only 12% of our lighting had been converted to LED. But the prices are falling and the experience of LED is improving dramatically. And very soon now the adoption of LED light to save on electric bills DOES now make sense and is going to take off like a rocket – exponential growth. And in a period of about a year EVERYONE is going to convert.

That means that 25% of our total national electric usage will be reduced by 88.5% to maybe 3% or 5% over the course of the next year or so.

Well that’s fantastic. Less belching smoke from coal fired plants and as everyone knows, if demand for a product goes down, the price has to go down too doesn’t it?

Not in the surreal land of government/huge corporate monopoly structures it doesn’t. It means drastically reduced revenues in the face of the same fixed costs. And so the PUC’s just have a little private meeting with the utilities and in a non-vote vote simply raise your per kWh rate. And batta boom batta bing, problem solved.

Sure, this will be offset somewhat by the adoption of electric drive for transportation. But I’m going to go out on a limb here and predict that your costs per kWh from the utility company are never going to go DOWN in rate. But they will go up. And potentially dramatically. Change causes the requirement to update things in fixed plant investment. And so it will happen.

Against that backdrop, about half of ALL existing residential solar installations in the U.S. have been installed in a little over the last two year period. While focusing on STormy Daniels and the plight of those piteous children from El Salvadore, the media may have failed to mention one of the most significant paradigm shifts in the last 100 years.

And 97% of those installations are grid-tied with no energy storage capability at all. And for good reason. Battery storage adds 50% to the price of an installation and the concept is you NEVER have to use it. The batteries go bad without ever being used other than the twice annual 5-minute outage. And so no one wants to pay that.

Of course, in the event of hurricane, tornado, flood, or zombie apocalypse, that $70,000 solar installation on your roof cannot actually produce enough power to charge your cell phone because on loss of grid power, it becomes TOTALLY INOPERATIVE. By design of the utility company in ANOTHER unholy deal with Underwriter Laboratories on the very pressing need to prevent injury to utility company repair workers of which NOT ONE EVER has had the slightest tingle from a solar installation to date WORLDWIDE.

I hear all the time about the vaunted Tesla Powerwall. I ordered one three years ago. I ordered one again when it was revised and updated and repriced. Hell I’ve ordered a solar ROOF from Tesla. All to no avail. They’ll let me know when they are shipping to my area. Why hasn’t this happened? After paying a brazillian dollars for Solar City, don’t they WANT to sell solar roofs and powerwalls?

They can’t get them approved. I’ve heard from several people who actually paid the price and took delivery. They eventually got refunds because Tesla cannot “get them approved.” In Australia perhaps. Or Puerto Rico. But not here. It just isn’t happening.

The utility oligarchy has already started the war and it has been raging for several years now. But they are using silencers and muffling their guns hoping you won’t notice until it is won. Which is odd because it was over before it began. They have all the artillery, AND your political structure in their pocket. But they are desperately afraid you’ll find out because sufficiently enraged, there have been set backs in some areas of the country by consumers and solar advocates. They are actually very fearful of this whole green thing. Indeed they are rushing to install huge solar installations of their own in a bid to claim the high ground here. Which is actually a good thing.

But they very much want to keep the serfs on the fiefdom and under control. And so teaching them to read and write is strictly verboten.

Edison’s original vision for his electric lighting system involved installation of a steam engine driven generator at each installation site.
This proved impractical because steam engines are noisy, smelly, require fuel, and are subject to frequent breakdowns. And so central “stations” emerged. Westinghouse used Tesla’s Alternating Current to allow large generation sites and the transmission of electricity long distances by wire.

Cool. But that was all developed in the 1880’s. That’s 130 years ago.

If we forget economics at the individual level, and also throw out the brazillions invested in the existing system, how would you design electric power production today from a clean sheet of paper?

And the thing that jumps out is we already HAVE solved most all the problems. You can use magic rocks on the roof to convert sunlight to electricity NOW and we typically just don’t do much with our roofs. They are kind of useless space required to keep the rain off and the sun OUT.

Sun doesn’t shine at night. Store the energy in batteries. SOME homes in the 1880’s actually ran on batteries if you can believe it.

And so you generate power ON SITE at the same geographic point where you USE it. Batta boom batta bing.

Electric grid? Why not? You can move electricity around. There is NO WAY to properly size a solar installation to use because the loads vary constantly and the irradiance of the sun varies constantly. And obviously, the sun goes down in New York long before it does in Los Angeles.

In an ideal world, the grid can be a balancing mechanism and economic arbitrageur of power economics. But it is extremely ill suited to being an energy storage service.

Battery storage has been problematic because of the short life, high maintenance, and large weight and volume of lead acid batteries. Lithium technology solves all of that but it is 3x the cost. But as we adopt electric vehicles, the availability of remnant batteries becomes obvious and the costs of lithium batteries repurposed to solar energy storage plummets.

Selfish Solar is a way to gain CONTROL over your electric energy future and insulate yourself both from the viscitudes of hurricanes and zombie apocalpses AND the frontal attack from your own utility service.

But in getting down to the where and the how, we have a couple of issues. First, all the producers of solar power management equipment are wrapped around an axle catering to the whims of the utility companies.

Second, they have been mired down in a never ending cycle of adding accomodation for yet another battery type/scheme/thingy.

And third, RETROFITTING grid-tied solar installations is just devilishly difficult in some non-obvious ways. The option to go grid-tied takes you down a very different path than having battery backup. And the central issue there is that battery based systems tend to be DC COUPLED in that the solar panels which produce DC power, and the batteries, which store DC power, are curiously ill matched to our universal 240vac two phase power system that ALL of our appliances and devices depend on.

Grid-tied systems by contrast are almost universally AC COUPLED. In that they convert the solar panel DC into 240vac at the earliest opportunity. And increasingly THAT opportunity is moving to the roof itself with small microinverters on each solar panel. Eventually these will simply move INTO the solar panel assembly itself and many future “solar panels” will simply produce an AC output. The wiring and installation issues all get easier when we can bring 240vac down from the roof already packaged for us and connectible to whatever AC system we have in the house.

So our quandry here at EVTV is how to use EXISTING AC COUPLED grid-tied systems with an incompatible DC storage device using the minimum possible equipment.

Grid tied inverters work by detecting the AC sinusoidal waveform provided by the utility grid. They then produce an output that is locked in both fequency and phase to the grid power system. By bumping the voltage just a few volts, they BECOME the current source for loads and the current flows from the grid-tied inverters to the loads. If they produce exactly what the loads require, the voltage of your house system will be just enough higher than the grid to keep from drawing any current from the grid.

In the event that the loads are GREATER than the power output capability of the grid-tied inverters, the voltage falls slightly. But you have basically unlimited power available from the grid to “hold it up” by providing power (current) into the house from the grid.

But if the grid-tied inverters produce MORE power than the electric dryer and air conditioner need, it simply increases the voltage ever so slightly above the grid regulated level, and your system becomes a SOURCE of current and power TO the grid.

This increase and decrease in voltage gets a little unmanageable to explain, involving phase shifts between the grid-tied inverter and the grid itself, but think of it as simply raising and lowering the voltage, ohms law being much easier to explain than RMS averages and phase angle relationships.

And I suppose it wouldn’t hurt to note that the grid-tied inverters detect the presence of the grid power NOT by power, but by frequency. And that a very small window of about 2 Hz off on frequency means LOSS OF GRID to the inverter.

Why is that important. If you lost the grid, and your power output exceeded the level demanded by the loads, the grid-tied inverters increase the voltage to export power to the grid. If the grid isn’t there, there is no place to export to.. And as the voltage rises, eventually the damage and blowup to the attached load devices and the grid-tied inverter itself ensues. And so normally there is some maximum voltage it will go to before protection algorithms simply shut down the inverter. Basically, the grid-tied inverters HAVE to have a place to “store” or export excess power to.

Enter the off-grid inverter. Since all the grid-tied inverters apparently need are a 60Hz sinusoidal waveform, the idea of using an off-grid inverter to provide an output for the grid-tied inverters to synch to arose about 12 minutes after the grid tied inverter was invented.

But if you take a 300 watt inverter working from a 12 volt battery, and use that to trick a grid-tied inverter into operation, experience indicated that it would work, but a few minutes later the 300 watt inverter blew up, and sometimes set the battery on fire. Then the house. Then the neighborhood.

And so using off grid inverters to energize grid-tied inverters without a grid, became a bit of a solar power faux pas. And that lesson has become part of the tribal lore of solar power. Don’t do it. It won’t work. And it will blow up all your equipment. Including your airconditioner.

I have been suspicious of this for some time. And so after developing our battery control system for TEsla batteries and battery modules, I had the instrumentation necessary to observe power flows in real time. And so we shut off the grid, entirely, and began experimenting with it. Remarkably, we didn’t blow much up. Indeed, within certain constraints it worked very well because the transformer based H-bridge inverters we were using allowed the excess power to basically reverse “rectify” right into the battery as DC.

There ARE a couple of provisos here though. The amount of excess power the off-grid inverter can absorb is limited by the power output rating of the off grid inverter anyway. So the 300 watt inverter was NEVER GOING TO WORK in the first place, simply by power rating. You have to use an off grid inverter capable of handling the maximum difference between what the grid-tied inverters produce and the load demand in BOTH directions.

That is, if the loads demand MORE than the grid-tied inverters can produce, the off-grid inverter has to make up the difference within its maximum power output level obviously. But the reverse is true as well. It must be able to ABSORB the power difference between max grid-tied output and loads within its power rating as well.

The transformer is probably important as well. It is a little old-school today, but it does an excellent job of providing isolation. But like all inductive devices, it also resists changes in CURRENT level. And so it is a bit “spongy” call it or resilient to changes in load and grid-tied output. Think of it as putting a bit of slack in the line.

Another problem is that if the battery gets full, and you disconnect the battery, all bets are off. You have lost your storage device to absorb excesses. And so the battery controller must be able to shut OFF the grid-tied inverters before disconnecting. The safest way to do that is to use our CHARGE ENABLE output to energize a relay connecting the grid-tied inverter outputs to the system. In this way, BEFORE reaching full, the battery can disconnect the grid-tied inverters.

We tested this on two inverters of two different manufacturers and at the 10kw and 20kw level several months ago and were amazed at how well all that worked. But it was using Tesla full packs of 300 to 400vdc. The peak voltage of a 240vac rms waveform is 240 x 1.414 or 339.36 volts peak to peak. Well that is right in the wheel house with our Tesla battery voltage. And so I could readily understand how the power was transferred through the transformer, and using exactly the same H-bridge PWM action used to produce the 60 Hz waveform in the first place, through the switches and into the battery in a kind of back handed rectification.

I advocate strongly for the use of full EV battery packs as solar energy storage. It caresses my sense of elegance that we could just take a pack out of a car, plug it in and use it without a lot of reengineering or processing. But quite beyond that, the current levels at 339vdc or 240vac rms are simply a great match for the wiring we already do. 10kW of power is about 30 amps at 339 vdc. And so 20 kW would be 60 amps. These are all comfortable current levels for ordinary house wiring.

The problem is that we have the vast body of viewers who want to experiment with this using weeny packs of two Tesla Battery Modules at 48v. And they want off the shelf MPPT charge controllers and inverters that are by and large 48vdc at this point. Indeed a 300-400vdc inverter has to be special ordered from China and there really just aren’t any available in the U.S.

But the 48vdc “standard” is not very well standardized, and really not a realistic solution unless you are building Tiny House Nation in Montanna. First, the voltages they operate at are really NOT a good match for the voltages of the TEsla Model S pack. And second, to do 10kW of power requires 208 amperes of current. That is signficant I2R loss as heat and you have to use huge cables. And this can be a bit misleading.

We use large cables all the time in electric vehicles. And runs are very short. But there is a false sense of security here. In an EV, we ARE at higher voltages. And while we might do 500 or even 1000 amperes, it is for six seconds. Not all afternoon. A 10kW CONTINUOUS load is a lot of current over a lot of time and so you get away with nothing here. We’re really talking 4/0 cable for even short runs if you want to install this safely. A cable fire NEXT to a lithium battery is little better than a lithium battery fire directly.

But it is clear I’m losing here. And I get it. Tesla Batteries are now $17,000-$20,000. They weigh 1330 lbs. And it is just easier to deal with the 27 inch long slabs at 56 lbs to build what you want. And while you could put them in series, the equipment to do 300-400vdc is again mostly unobtainium.

The problem is, the inexpensive and commonly available 48vdc product out there is just not well suited to the Tesla Battery Module Voltages.

First and most dangerously, almost all the battery types supported want to charge to 56v or higher. If you charge a 2S1P Tesla Battery Module set to 56 volts you will at a minimum destroy it completely. But you risk fire and explosion.

As well, the low voltage cutoff of most 48vdc inverters is 42-44vdc. At 44vdc the Tesla System is at about 56% state of charge. You’re leaving half the capacity of the battery on the table. A 20% level of state of charge would be down around 38.25 volts. And 36.5 volts to actually cutoff operation would be perfectly reasonable.

So we went to a Chinese inverter manufacturer who makes a 48vdc inverter we like and asked them if we bought a small quantity of these would they add a battery type catering to Tesla Battery Module voltages. And they did. We just got them in and began testing and were delighted to find that they worked perfectly with our Tesla Battery Modules.

The unit is 175 lbs and uses a large copper transformer and some good switching electronics. It has three fans that are controlled to come on as needed and the box does an impressive 12kW of continuous power and a whopping 36kW peak output for up to 20 seconds. And the pricing is very good. We can buy them in quantity, ship them here and offer them at a profit at $2995. That’s under 25 cents per watt.

But the really good news is it allows us to start eliminating other devices wholesale. It features an AC input that can be grid or generator. And it will automatically use that input to charge the batteries in the event that battery voltage falls below the battery alarm voltage of about 39v as we measured it. It can charge at up to 120amps. AND it can power the loads while it is doing that. So our 6kW grid tied charger GOES AWAY. The charger is built in.

And so you can use the grid as backup if the battery is drained too low, and indeed you can use a generator. It even has a generator start relay set when it needs to charge. You can use this to start up your generator obviously. And it will wait up to 15 seconds for a stable AC waveform before it starts the charging process. This is rather important when working with generators.

The question then becomes, can we make the MPPT charge controllers go away? And I say controllers plural because as battery sizes and arrays grow, we find the choice and power levels of MPPT charge controllers somewhat limiting. When you get up into the 3kw to 5kw range these things get expensive. And if you want to make use of even a modest 10kw array, you are using two or three of them.

Well there is a way. And it goes to making our system work with EXISTING grid-tied photovoltaic systems anyway. Our Solar Edge grid-tied inverters, for example, use series strings of panels at around 500vdc to make power. 500v is far too high to work with MOST economical MPPT charge controllers which tend to be limited to 100v or 150v at best. We’ve found a couple but they are pricey and a bit erratic frankly when charging to our 50v charge limit.

Many installations today use microinverters on the roof – one per panel that actually produce 240vac down to the equipment room. And so the ability to use AC coupling to existing grid-tie inverters would be huge.

The question is can we do the same charging from grid-tied 240vac with this 48vdc inverter as we did with the high voltage inverters with the full battery pack.

The manufacturer assured us that it absolutely could not and would not work ever under any conditions. It would just shut down automatically and entirely if we tried it.

Well, we ARE located in Missouri. So you kind of have to SHOW ME. I’m not very good with the “being told” thing. In this video, we demonstrate our test results.

One of the things that keeps me going around here is days like that. The results were frankly astonishing. We hit a peak of 280 amperes, 13,500 kw of power IN to our battery through this inverter WHILE the entire shop was running on the Solar Edge output at about 4,500 watts. And we did 230 amperes for 40 minutes until the battery was charged.

The inverter ran cool and quiet without complaint throughout. Never a hiccup.

In surveying this, I would like you to note again the relationship between a 12kW inverter capable of brief sojourns to 36kw, a 25 kw max array output from the grid-tied side, and a battery capable of 1300 amps by design. I don’t think any of this works with a little 5kw inverter.

That said, do note that the cell voltages for the Nissan Leaf and Chevy Volt batteries are essentially the same as the Tesla Model S, 3.6v nominal, 4.2v max charge, and about 3v fully discharged. So voltage wise, the Tesla Battery Module Setting on this inverter would work quite well with those batteries as well. I just ordered a kind of old beat up Nissan Leaf battery pack from eBay for $2300 and we have a new addition to our clan who is working on a controller for the Leaf. A 24 kWh battery probably working at 18kWh at this point is not precisely where we want to go. But it is budget minded at $2300, about the cost of two Model S battery modules.

What remains is to control the Solar Edge output when the battery gets full. We intend to do that with normal contactors on the summed output of the Solar Edge inverters. We’ll use the CHARGE ENABLE output of our battery controller to energize those contactors, and so when we reach the fully charged voltage set in the configuration, the contactors will de-energize and disconnect. When the battery stte of charge falls to the RESUME level, the charge enable output will again close the contactors, and after a 300 second timeout, the inverters will produce again.

Tnere IS another technique I would like to dabble in. Ostensibly both the Solar Edge and Enphase grid-tie inverters have a bit of a hidden feature. If you shift the frequency of the off-grid inverter between 60 and 62 Hz, the inverter produces 100% power at 60 Hz and nothing above 62Hz. But if you could shift it within that window, you can actually modulate the output from 0 to 100% in quite linear fashion.

Unfortunately I have discussed this at length with the inverter manufacturer. Subsequent to our testing and this weeks video they are really QUITE interested in working with us further. But they are literally out of memory space on their current microcontroller. So adding CAN control is kind of out of the question at the moment. But we continue to head scrum on possible future products. They are awakening to where I want to go with this.

Of course, it is a serious disappointment that American made componentry suffers enormous arrogance and hubris sufficient I cannot bear to even discuss it with them. They embarrass me mightily. That is I am embarrassed FOR them. Often relatively small in both size and sales, they have somehow developed the idea that if they ACT like a big stupid corporation, they might get to be one someday. I can only shake my head in wonder and hope they get what they ask for. Punishment enough.

Click on the manual photo below to view the current state of the documentation for this inverter which is now available in our online store.

What’s left here? Well quite a bit actually. We want to perform this testing with Enphase’s new IQ7x microinverter. We’re still waiting on availability for this latest microinverter as it works with large panels of up to 96 cells and was specifically designed for the Panasonic HIT 300 watt panels we already use on our 13,500 watt test array. You might find it curious that Enphase just recently invested $25 million in a 10% stake in SunPower Solar. Recall they make the 22% solar panels and cells that we use on our flexible solar panels. They are going to retire their house microinverter and use the Enphase model exclusively. Long term, I would look to them to do the first viable solar panel with INTEGRATED grid-tie inverter built into it. This would seriously decrease installation costs and complexity.

This week we have begun a new project. We are going to call it the PowerSafe 100. This will be a single cabinet using a very strong heavy Wiegmann NEMA enclosure made of 12 gauge steel. Lifting eye bolts on top and heavy duty wheels on bottom. This monster will be 72x36x30 inches and weigh right around 2000 lbs. But it will hold 20 Tesla Model S battery modules for a slick 100kWh of storage. It will include the 12kw Inverter inside with a liquid cooling system for the batteries, solid copper bars for the high current connections to the inverter, and a control panel mounted in the door sporting our EVIC display and SUB and CAN ports and all manner of switches and dials and controls.

The idea is to get everything in one box and only do AC connections to it. Grid/generator in one port. AC output to your loads panel out one port. And a third port to connect 240vac from the grid tied inverters on the roof. Perhaps a generator start output. This should be enough to power any reasonably sized large home with a couple days storage and the idea is to easily connect to an existing grid-tied solar installation without having to redesign the whole thing from scratch. As we adopt LED lighting and more efficient heating and cooling technology, the storage will actually appear larger and ever more useful.

We see that as a $50k solution probably not attractive to most of our viewers but will demonstrate about the level we think all this will be at in a few years. At 50 cents per watt it is right in line with Tesla’s Power Wall, but you can build it yourself and if you fail to mention to the utility company that you have installed it, I’ll try not to spill the beans from this end. And of course it is 10x the storage capacity and twice the power output.

The enclosure looks a bit to me like a largish gun safe. Ergo the PowerSafe 100 project title. And of course all the piece parts are pretty much already available in our web store if you want to follow along the build yourself. We hope it will BE safe of course but we actually named it after A safe.

I see this as more or less what a future home power station looks like. And I really think it’s possible and workable right now, if perhaps not economically attractive yet to the consumer. If you want to play, we think we can enable it.

34 thoughts on “100kWh Tesla Power Wall on Steroids. The PowerSafe 100.”

  1. When we build a house in a few years, we want to set it up specifically for selfish solar. Hopefully Tesla’s solar shingles are more widely available by then because that’s much more attractive, and easier to “hide” from the power company. I’m sure once selfish solar becomes more widely adopted, they’ll try to find a way to squeeze more money out of us just for the honor of having their meter on the house doing nothing. Once model 3 and model Y hit full capacity (model Y 1M/year?!?) what do you think full battery pack prices would drop to? $5k? $1k? Hopefully by then they’ll end up like regular ICE cars in that every junk yard will have one available to pull the pack from. If price drops that much, then it would be a no brainer to put 3-4 full packs in a dedicated “power shed” for your house. (I’m thinking fully concrete building with dedicated lithium fire suppression.) I’m unbelievably excited for the future of solar, keep up the videos and posts!!!

  2. There is no such thing as “out of memory space” when it comes to software development. We all just say things like that when we don’t want to try to make it fit. It’s almost always possible to code the existing stuff 5% more efficiently then squeeze in another function. Though, obviously this does eventually break down. Memory and FLASH are not infinite nor is room for optimization. But, generally the room is there but the “gettin’ around to-its” are lacking. Though, quite often the work required to shoehorn another thing in there is more trouble than its worth. It’s a shame, a CAN connected solar inverter would be pretty cool.

    1. Errr…as I recall we kind of DID run out of space on the CHAdeMO controller. Well maybe not OUT but we could see the end in sight.
      Recouping space is kind of by successive approximation. You can get quite a bit by a simple refactor. And you can get a bit more with careful further coding. And you can get a wee bit more with another pass. But with each pass, it gets harder to do and the results decrease further.

      With the prices of hardware these days, it’s a total loser. It’s kind of like cleaning up your hard drive to recoup space. Why? Just buy more drive. It’s easier and cheaper than the time expense.

      They picked the wrong controller. Pure and simple. Trying to keep it cheap. With the current cost of chips, it is always an error to economize. I say buy three times the chip you could ever possible need and go ahead and eat the $4 per unit. You just can’t predict the targets of opportunity that will appear in software once you are up and running and see what you could REALLY do now that THAT part works. Speed and space are coin of the realm.

  3. I am planning a tiny house with solar power, at first I hope to run just off solar power but if it turns out that I need to use the grid-power I also am going for selfish solar. And the main reason for me is if my system CAN NOT output power to the grid, then there is no chance that I will electrified so poor line man working to repair some damage.

  4. selfish solar… make it connect via chademo to packs still in the car, thus enabling EV’s on four cinder blocks with no tires next to the house… I can already picture it in our southern home

  5. Jack, Looking at the date of the bill, I would say you missed sized the system in that the break even month is 04 to 05 not 12 to 01 as it should be with net metering sizing as to always give you a small bit back in the winter and more back during the summer. Note: I am not disagreeing with you with SS, but adding to the point of the cost to break even. The amount of panels and equipment need now to do what I suggest has a cost and this is the real cost of making the system become a year-round producer. Be careful what you wish for, because they might change the rules and make it cost to do that.

    As to the taxes on the service fee, you could got to local media outlets and inform them of the issue. I am sure no one want to pay taxes per kWh on some thing which is not a kWh. I can see them reacting however by making it count to sales tax instead, so be careful what you wish for.

    To the SS system, here are some questions:

    Can you add to the store a diagram of how to wire this thing up when grid is the primary backup and a generator is secondary backup? I am thinking of how to keep it safe with both of these AC sources and not shut itself off for being a source or line back-feed. Also, can you test it?

    When will the grid inverters contactors be ready to buy? Also, can you make it work 1 inverter 1 contactor 1 breaker inside a combiner / breaker box? What I want to do is shut one inverter off at a voltage level at a time.

    12kW / 37V > 300A. Wires for this? Breaker?

    I am guessing that the 100kWh box cost will be more than a Tesla battery and everything needed to connect? Can this box be turned on its side on top of a small trailer with weather proofing to keep water out of the box?

    1. John: You kind of remind me of the neighbor in the Home Advisor commercial. Sure, I’ll just drop what I’m doing and rework the entire planet for you.

      The inverter features an AC INPUT. It can be a generator. It could be the grid. I don’t guess there is any limit on what it can be from, but it has to fall within the range of voltage listed in the spec and at the 60Hz frequency.

      Contactors are in the store now. Any contactor that will handle the 240 and has a 12v coil will work.

      You have ONE charge enable output to work with. So shutting down the five Solar Edge inverters individually is not possible at this point. It would take another device with five outputs. I suppose it could monitor our CAN output for voltage level.

      Jack Rickard

    2. John:

      You think we should price the 100kWh box at MORE than the cost of the components and everything needed to connect? I’ll consider it. We were of course going to price it at HALF the cost of the components and then try to make it up on volume as it will only take us about a month to build this thing.

      1. We can do stuff.

      2. We can show you how to do stuff. And yes, I guess we do pay the expenses of showing you how. I guess if I could figure out how to get you to pay $15 to view it, that would be nice. And you do that routinely with movies so it shouldn’t be to big a deal. But I’ve just never pursued it. Seems like we should share it somewhat freely. Or that is how my whimsey goes.

      3. You can build it using your own stuff or get stuff at the hardware store.

      4. But yes, if you want to use exactly what we used, we’ll sell it to you – at a profit. That will actually save you from the effort WE went to to track it all down.

      What we can’t do is build stuff and pay you to haul it away. You would be surprised how OFTEN I get inquiries regarding this. Well maybe not. But I am always surprised.
      So you don’t mind paying for the modules. And you don’t mind paying for the stuff to interconnect it. But you’ll go straight to hell before you would pay me to do anything. And this after I have already given you the information freely and urged you to do it yourself?

      The sense of entitlement in this country and the deep deep entrenched belief that the entire world is all about ME is just astonishing to me. I am in awe of it. Again, it’s not that I take exception to your position. I can’t figure out why you EXIST AT ALL?????

      Please refer to my recent blog ALL THE NEWS THATS FIT TO PRINT. I do, as I have always done, look for ways that I can be of service to others and do anything I can to make the world a better place. This gives meaning and purpose to my life and so puts me in a more or less constant state of joy. Joy is somewhat different than happiness. Happiness is kind of a momentary fleeting thing like having too many beers or hearing a good joke. Joy is a kind of gratitude for life itself and an optimistic expectation of all the good things that are going to happen today, largely because I myself live and breathe. And it continues day after day and year after year. If any rain should happen to fall on my little world, I can easily endure it in good cheer knowing it’s all part of God’s perfect plan and in the end will be for the good.

      I can’t imagine spending all day striving to see what I could GET for ME and who I could talk into giving it to me, as my main purpose in life. It would certainly be a miserable, loathsome, depressing way to waste my life. But it really does seem commmon. Is this why so many are so unhappy and devoid of all joy?

      Caught me on the wrong morning I’m afraid. Sorry.


    3. Oh, and in reply to what is probably your real question – $50,000. That would be 50 cents per kWh and that seems about the correct pricing to me. But I’m kind of pulling that out of my ass.

      As I recall, Tesla is doing their commercial units at about $1.50 per wH. Love to have the latest on that if anyone knows.

      Jack Rickard

  6. Hi Jack, always enjoy your posts and videos – first time communicating in any manner, just not something I usually do online. I’m very thankful for the work and thought you put into all you do and your willingness to share. Not to blow too much smoke up your ass, but you are always entertaining, while providing incredibly valuable information and experimentation that I find completely interesting and absorbing.

    Anyway, risking a nube question here.

    Would it be possible to run two of the 12kw inverters in parallel? For my home scenario described below, and because of my unwillingness to change my general lifestyle (other than to cut out all thoughtless energy usage) I’m thinking in terms of a system setup somewhere mid-way between the 12kw inverter/charger setup, and your full blown $50 system . A first blush, it seems a system made up of two 12Kw inverters/chargers running in parallel would give me the safety/wear-n-tear headroom I like to build into my systems – but not sure if that would be possible, or be a stupid idea for some other reason – even if technically running two in parallel were possible.

    My home here in Arizona, during peak heat 1-6pm would put a pretty good load on the 12kw inverter and probably cause significant heat generation on the cables/connections during that period. Based on your testing, it does seem like a single 12kw inverter charger could handle my home without me making major lifestyle adjustments (after already converting to all LED, using home automation to minimize light/power usage, etc), but it would be almost fully saturated during summer days from 1-6, maybe even through 8pm, at which time the house is fully cooled down again, and household cooking/chores etc wind down through 8pm. So, this makes the risk assessment project manager part of me want to plan for slack and headroom. Not $50k worth of headroom, but maybe $3k for a second inverter doesn’t sound unreasonable, and would seem to allow for some redunadancy.

    During peak summer hours my loads are about 7-11k from 1-8pm for solid 45-70 minute cycles, with 15-30 minute off/lower cycle periods. I do currently have spikes of up to 14k if the timing of both AC units and the Volt charging, and/or the electric drier all happen to coincide. I already control these during the “peak” utility price hours which are 3-6 at which time my entire home (~3700sqr foot) runs on about 450-600 watts for these three “on-peak” hours of the day. I pre-cool heavily during off-peak hours, so its bearable to have no AC for just a few hours, and that 450-600 watts still includes running refigerators, several computers and NAS systems, and security cameras that run 24/7 and what ever TV/lights the family does happen to turn on – because they turn right back off if motion detectors decide nobody is in a room!

    Anyway, I know I have the mechanism in place already turn on/off any individual units to keep the loads under 10k when needed – but there are fairly long periods between about 12pm and 8pm where the inverter would run at near capacity to keep the house livably cool. from Jun-Aug

    That’s my question, and the context for what it’s worth.

    Your big mama system is very cool, I look forward too hearing what happens with that – glad you’re setting up for that and would love to see that turn into a business for you, and for our communities.

    1. Thanks for writing James. Interesting question from several angles largely due to the detail you provide in your usage. I get a lot of will it work questions that sort of depend. The application rather matters.

      The quick answer is no. You cannot “parallel” these inverters in the sense of marrying them into the same system and having them produce a coordinated or in phase output. They just don’t do that. No provisions for it at all. If you connect the outputs together, the normal outcome would be to blow both of them up. Dueling 240vac at up to 36kw – for a moment. Total shitshow.

      As you know, I think simpler is better and I would attack this problem with a simple 20kW inverter and use the full pack voltage. I really don’t understand the resistance to this concept. It seems ideal for your situation. I can get you 30kw and we’ve sold several at 50kw for that matter. The higher voltage just makes all the wiring easier and less trouble prone.

      ALL OF THAT SAID. You seem quite knowledgeable about your existing system. And redundancy IS kind of cool. And in this case literally “cool”.

      You CAN run multiple 12kw inverters. They just cannot be on the same circuit at all.

      You have two air conditioners and then your house. Why not dedicate a 12kw to EACH air conditioner. And then a third to your normal loads panel. Disconnect both air conditioners from your main panel entirely. ANd connecdt each to its own 12kw. You might get away with one 12kw for the two air conditioners. But my mind goes right to the one inverter per air conditioner thing.

      It IS possible to run all three inverters from the same DC INPUT. SO one battery pack, three inverters. But it is absolutely imperative that the AC outputs of the inverters NOT be on the same circuit.

      AC normally has its own 60 or 80 amp circuit breaker in the panel. It’s kind of a matter of removing the connection into the panel and rerouting it to another add-on circuit breaker panel that is NOT connected to the grid or the first panel.

      YOu can of course tie grid-tied inverters to any of the three and have that one charge the batteries.

      So if you had one inverter for your main house loads panel, and one inverter for each air conditioner unit, and all three tied to one battery pack that would all work just great.

      At that point you have a lot of redundancy and repair replacement options in the event an inverter goes out. And a lot of overhead on your capacity.

      I’m not really developing a business here James. We demonstrate how a business could work and often that there is a demand for it. We don’t really price things at what we need, but rather at what we think would be appropriate if someone took that and did it as a business to cover overhead and the expenses of running a business. Then, if anyone salutes, that must mean demand for it.

      1. Thanks for your reply Jack, makes sense and I like the idea of dedicating a 12kw to each AC on separate circuits. Meets my desire for redundancy with Chinese inverters, and solves for not being able to running in parallel nicely. Also would allow a person to build up to the system as chunks of money free up that can be applied toward solar/batteries/inverters – for those of us still navigating our way through our first rodeo.

  7. Pingback: Using Bolt Battery as home emergency backup - Page 8 - Chevy Bolt EV Forum

  8. Love it. This saga reminds me of the story of some pioneers of RE inverter technology that we still depend on for equipment, even at low dc voltages.


    Great stuff. Our customers have been asking for years, about incorporating EV storage and charging with RE system and we have been at a loss to help.

    I have been a renewable energy installer and system designer for 14 years and am watching on the edge of my seat as Jack does his thing. I did see the merging of EVs and home power (great magazine publication) as a facility early on but we are off the shelf “designers” and mainly select and integrate equipment.

    Although i have a nega-watt pv system and i never buy anything, my clients do and only if i know of solutions.

    I am committed to change this to adopt EV use and so this site is of great inspiration and high value, a forefront information exchange on the topic constellation which is heavy politics and nescessary development.

    Thanks again, Jack. For the politics and the development.
    (He just calls them up and asks for more voltage…..!)

    1. I’m pleased to see a lot of installers and systems designers coming onboard EVTV. They tend to validate what I’m saying on many fronts. And it’s not precisely an “experiment” with them as much as a pressing need.

      I’m not really just discovering solar as you may have guessed. I installed a 15kw system in my home in Denver in 1998. Prices were higher then. I spent $275k on it and at the time, it was the largest residential installation in the world. That was 20 years ago of course.

      Rather haven’t been looking at it much in recent years. But in my current revisit, I’m amazed both at how far it has come, and how far it has gone astray.

      Connection in interest between solar and electric vehicles is not random nor limited to me. ALL of our viewers have been on me to do more on solar for a number of years. There is a big connection in interest between the two.

      But I find it a little daunting. There are a number of people who will in fact go into their garage and try to convert a car to electric drive. But there is a hugely larger number who will put up solar. So it’s a much larger audience and my e-mail load has jumped 10x.

      Welcome aboard

  9. Hi Jack,

    Thank you for your hard work and for posting online, it is much appreciated.

    I completely agree that the net metering system is a scam and it is in everyone’s best interest to install solar and batteries, instead of pulling from the grid in the afternoon evening and tier 4 and 5 rates. In fact, SDG&E where I live (southern California), just announced in March of this year that anytime you pull from the grid between 4-9pm, no matter your usage, will be at their highest tier. This is net metering scam at its finest.

    I recently contracted a local roofer and electrician and had them install a 10.44kW system on my roof with a SolarEdge inverter, compatible with a whole house battery installation.

    Over the last few months I’ve been researchIng battery options and the Tesla Powerwall and LG Chem systems are just not cost effective, even with the California Rebates.

    Instead, I’ve been researching how I can buy maybe ten, 5.3kWh Tesla Battery Modules – https://goo.gl/QPCVvR (maybe these) and everything else needed to complete this setup…. this is when I stumbled onto your channel on youtube and then this website 😉

    My question to you. Can you help me accomplish the above and or potentially (for a fee of course), work with my local electrician to accomplish the same?

    I am ready to move forward immediately.

    Thank you!

    1. Brandon:

      Well that’s what we are all about. But no, if I understand your inquiry correctly, we are not in a position to work with your electrician, do installs, or really interact with the consumer world of solar in any way.

      We are not really solar installers. We only play one on TV.

      The mission we have taken on is to reverse engineer EV batteries for use in solar storage. And we do some design work on what we term “selfish solar” to show how to survive and thrive by generating, storing and using electric power at the point of use.
      We routinely use custom inverters obtained from off-shore manufacturers and care nothing for Underwriter Laboratories, the bizarre matrix of local building and utility codes, etc. Indeed we’ll use pieces of wrecked cars, hardware from
      Loewes, consumables from Sam’s Club, and crap we have laying around in the shop floor.

      We do take great care not to pose a threat to our building, our employees, the utility grid, and our neighborhood. Our solutions are based on sound engineering principles and if anything overbuilt for the proposed application. Most of our inverters, for example, are in the 10-30kW range in world where the average American home averages 1.25 kW per hour and need peaks of 6kW of total power.

      Our viewership is generally also dismissive of the rules and regulations promulgated by the utility grid monopolists. And we do provide key piece parts they use in their own designs that may be inspired or motivated by our demonstrations.
      Increasingly we do find additional viewership in the professional solar installer community, who are actually more familiar yet than you and I that something is terribly wrong in the heart of solar energy at a practical level.

      Worse, you can be ASSURED that if we are doing it at this point by demonstration, it is simply ridiculously uneconomical for consumers at this point. By the time anything we do makes economic sense, and it soon will, we typically haven’t been doing it for four or five years.

      So unless you are beginning to develop a strong urge to do-it-yourself and join the ragged army of tinkerers and innovators who play with such things and pay dearly for the opportunity to learn and discover and beat the game, you want to move along to some heart warming and satisfying cat videos or something. Your “electrician” most likely would not approve of my EXISTENCE and will assure you most readily that EVTV is entirely nonsense. And indeed from a certain world view, he may have a point.

      Bottom line is that everything here costs too much, has no economies of scale, and we blow up more shit than MythBusters.

      But hey, what’s the payback period on a bass boat?

      We get oxygen from the sale of things like Tesla Model S battery modules, controllers, and CAN port hardware and switches and contactors and so forth.
      Our viewership supports us largely by buying all that here, and yes of course they can just as easily get it on eBay. We are not really in a position
      to provide hands on product support for eBay. But we don’t in any way discourage your use of it.

      Jack Rickard

  10. Pingback: Check Out This 100 kWh Tesla Battery Energy Storage System

  11. You talk about inverters being used as chargers, do you think the 11kw charger (or twin 22kw total chargers) in the Tesla could be run as inverters to provide AC right back from the car or storage battery connection? Maybe throw a couple in your safe and makes withdrawals all night long.

    I’m all for recycling as much of the 2nd life equipment as possible. I love the selfish solar approach and I’m looking to expand usability to urban and suburban situations.

    Best regards,

  12. Do you think you’ll get taxed on the income you make from the sale of the solar back to your utility? You might if they report the payments they made to you so they can write those costs off on their taxes. There goes your $0.05 swing (before “consumption” taxes)?

  13. The idea of selfish solar appeals to me. I have been looking for a whole house backup that is AC coupled (I am getting 11.2KW of Panasonic 96 cell panels with IQ7X micro-inverters installed in the next couple of weeks). I am out here in California – the land of regulation. All of the solar contractors assure me that you can’t do this whole house backup- you have to have a separate critical loads sub-panel. I have been playing with a small 36 VDC off-grid 240VAC SP inverter to sync a micro-inverter. I was using a bunch of 36V hover-board batteries in parallel and charged it off the grid. It works but there are a lot of problems handling the variations in load and how to safely disconnect from the grid. According to the Tesla web site and some YouTube videos you can do this provided you can actually get some Tesla PW2s with backup gateway. The delivery timetable for Tesla is now “not definable yet” however and I am thinking that there might be regulatory reasons for the delay. Your 12KW inverter system looks intriguing. What else is required besides the Tesla battery modules and this inverter? Thanks for the video.

    1. We are waiting for some IQ7x microinverters to test with. The “grid” interface with our inverter is pretty simple – a transfer switch within the inverter. You place it BETWEEN the grid and the loads. And it will only do 12kw continuously, though 36kw for surge.

      We fired up the PowerSafe100 in anger yesterday afternoon during a rain. I was disappointed we couldn’t test with the Solar Edge inverters. But magically the clouds parted and we had a PEAK charge rate into a 100kw 48v pack of 242 amperes. The 12k never whimpered. Not a peep.

      The issue of course is that you may not overcharge the batteries and so need some active means to disconnect the grid-tied inverters once the battery gets full. Properly sized, the battery would never reach full nor empty. But sizing is an issue.

      There are actually ZERO issues in the transition from the grid-tied array making too little or too much power. It works entirely automatically and without intervention. The entire issue is overcharge and overdischarge. If we reach too low a voltage, the 12k will switch to grid power and not only pass it to the loads but use it to charge the batteries. And with regards to overcharge, we use the CHARGENABLE output to control a contactor on the grid-tied input. We simply disconnect it.

      We continue to investigate the POSSIBILITY of doing this with a frequency shift. I’m awaiting prototypes from CHina.

      We are meanwhile entirely sold out of the 12k. The next batch is still a month out, and they will be a brand new 15k model, meaning we have to test all this all over again. But it gives an old man something to do of an afternoon.

      1. All that said, we are an outlaw outfit doing outlaw hardware and software. You’ll never be able to do any of this legally with anything from us. I would say no legitimate solar installer would touch it, but actually we are hearing from a number of them that want to learn about it anyway.

        1. Thanks for your quick responses. I was curious about the power monitoring systems you were showing when you tested the 12KW inverter. Are these something that you market? I am aware of your status as outlaws. It is the only way things will get done.

          1. Well our Tesla Module Controller gives us a lot of information. We have a new Raspberry Pi Display for that though we used the EVIC display earlier.

            So we can watch it pretty closely.


  14. Hi Jack,

    I’ve been following you here in Singapore since the early days of EVTV, and I think this selfish solar (PowerSafe 100) is a brilliant idea. Imagine all the homes that can benefit from this.

    The cost now maybe prohibitive but surely in 5 years time when you’ve got it dialled in, the cost will significantly go down.

    I’ve seen your video about this and frankly I am so impressed and I wish you all success for this endeavor.

    This selfish solar project of yours has a deep social dimension that would be a game changer for anyone interested in Solar.

    I wish you go back to your original pace of 1 video per week.

    Marlou Jasmin Madrio +65 9770 9358

  15. Is the PowerSafe 100 available to order?
    My order spec would be (subject to advice) :
    1) 75 or 100kWh of Model 3 batteries with cooling.
    2) batteries in their “skateboard” pack on wheels to be easily relocated
    (for use as home backup generator and time-shifting grid power storage and “selfish” solar pile)
    3) transportable in an enclosed race trailer to take a Model 3 PUP to the track
    4) plumbed into a HPWC at its highest power configuration (100A 300V?)
    (or whatever can be achieved, maybe staying DC-DC if the HPWC can drink DC?) to be able to charge in the paddock.

      1. Greek? : )
        1) $75K is too much for my modest needs (more like a 25kWh system would suffice)
        If you wanted to price a smaller PowerSafe with less battery capacity, preferablly using say one 25kWh segment of Model 3 batteries, that would better suit my budget/needs.
        2) I’d rather the design be to keep the Tesla pack unopened and using its cooling system since that seems to bring longevity.
        3) my “rationalization” for a Powerwall or PowerSafe is to have a portable battery system
        I’d use it to power a Tesla HPWC to recharge a Model 3 PUP at the race track
        Since the HPWC doesn’t do much except AC->DC … maybe it could be modified to take DC and just do the handshake with the vehicle’s onboard charger (ideally allowing a PUP to charge at its 48A rate or an X at 72A.)

        The “paddock” is the parking area around a race track “pits” for teams to prepare their cars.

  16. Zaid Saheed Sanni

    how much does it cost ,including shipping to Lagos,nigeria. sent you an email this morning.this would help in my rural electrification project , grid tied and solar preferably

  17. Question if you don’t mind.

    What kind of “Battery Controller” are you using that has a Charge Enable on it?

    Below is the paragraph where it was mentioned.

    What remains is to control the Solar Edge output when the battery gets full. We intend to do that with normal contactors on the summed output of the Solar Edge inverters. We’ll use the CHARGE ENABLE output of our battery controller to energize those contactors, and so when we reach the fully charged voltage set in the configuration, the contactors will de-energize and disconnect. When the battery stte of charge falls to the RESUME level, the charge enable output will again close the contactors, and after a 300 second timeout, the inverters will produce again.

    1. We have a controller that talks to the BMS boards on Tesla Model S battery modules. http://store.evtv.me/proddetail.php?prod=esp32bms It has a CHARGENABLE output that you can set to come ON at the RESUME voltage and OFF at the CUTOFF voltage. Like CUTOFF=4.15 and RESUME = 3.85. So if the voltage falls to 3.85, it comes on, and when it reaches 4.15 it goes off. This is a switched ground and 12v output you would typically connect to a relay or contactor. Might be an alternator output, MPPT Charge Controller, etc. In this way, you can determiine when your batteries are charged or when charge is cutoff.

  18. Hello Jack. Really geeked to have found your website. I’m curious to hear if you’ve looked at a small scale variable frequency transformer for controlling the flow of AC from one AC bus to another dynamically by controlling the torque of the DC armature (which is mounted on a common shaft with an AC induction armature.) They use this pairing currently to charge tolls for power flowing between NY and NYC. It’s a relatively recently commissioned addition to a combined cycle central power station. The station is in Linden, NY. Hydro Quebec also uses them as a means to convert DC to AC on a large scale as opposed to the HVDC stations on the western edge of the Eastern Interconnect.

    I’m a long time EV enthusiast, and have been dreaming for a very long time about a solution for the people (to take back this rigged system — at least in part — for their own benefit) with a reasonable payback. I think you’re right, we should be on the edge of some radical paradigm shifts in the near future. It’s an exciting time to be alive.

    Thanks for you time.


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