I'm planning to make a 'box' that can switch between the 2 functionalities on the same cable.
The whole setup is a bit clunky as it is right, now, but I'm kinda more surprised that it works at all, and how well the fundamentals work.
This whole thing was more of an experiment in 'no way you can do this' to actually doing it, but I think this is HUGE, and will transform the way people think about electric cars.
Aren’t most people at work / school when the sun is out?
If you're not worrying about A/C then 1.5kW goes an extra long way. Outside of cooking you'll rarely exceed it.
Also, this idea that higher usage overlap with the sun being out is laughably wrong. Solar noon is between 11 AM and 2 PM. Very few people are home at that time. There is a reason that peak grid demand in almost every country is in the early evening.
Does that change anything about what I said? This is specifically about "if you do have supplementary house batteries".
> Also, this idea that higher usage overlap with the sun being out is laughably wrong.
The reason we have the duck curve is that insolation and demand largely overlap (especially when we're talking about the worst case part of the summer), but then for part of the evening they really don't overlap.
The peak use is evening, but there's a significant ramp up when the sun rises and the whole day is much higher than night. https://ars.els-cdn.com/content/image/1-s2.0-S03062619173137... (This isn't the US but finding household graphs in particular is annoying, and most of the US has more summer heat than denmark)
Anyway evening is one of those bursts where you use the supplementary battery to handle the rest of the load. Even 10% of the car's capacity, 6kWh, could cover almost all use above 1500W.
> In much of the rest of the world, electricity demand peaks in the evening
Huh?
And again my chart showing that the entire day has much higher use than at night, then an extra high peak in evening, was Denmark.
1. Does the solar inverter do away with the need for a V2G or V2H unit?
2. What are the limitations vs a dedicated V2G/H unit?
3. Is generator input on your solar inverter a common feature across inverters?
2. Tbh not super familiar with V2G/V2H, other than it being super expensive for both the wall box and the car (only high end models tend to support it)/
3. No idea, but it's not a high end feature, I wouldn't count on any inverter to just have it, but if you're looking to buy one that does, I don't think you'll be breaking the bank.
Imo the future is for solar inverters to offer a dedicated DC car charger port, as once again all the hardware is already in there.
As long as the inverter can also provide charging this definitely has some potential.
My first 14.3 kWh pack cost about 2800$ DDP from China, delivered 03/2023. For that one I did calculate how long it took for amortization, which I projected at about 5 years.
The second, identical pack was delivered 08/2024 and cost 2000$ DDP. Since we got an EV that's drawing about 14kWh per day, I didn't bother doing the math and just ordered it.
These are 280Ah 16S 51.6V packs, based on the EVE LF280K. In an enclosure, with a BMS (Seplos, 200A) and a dedicated balancer. They are good for 6000 cycles at 140A or less [each]. Mind these were both part of small bulk orders - I think each time we ordered 6 to 8 of these, which reduced shipping costs.
If you don't work from home it makes 0 sense either.
IMO we are long way from proving V2G usefulness. Micromanaging your car SOC every night to save $2 is nuts.
I'm just pointing out this is way lower than typical pricing
[1] Three-phase wiring in homes seems to be very rare in the US, but is extremely common in Europe.
But you're right, most installers do high voltage batteries.
https://www.canarymedia.com/articles/distributed-energy-reso...
https://enphase.com/blog/homeowners/understanding-nem-30-and...
I believe that's more a function of auto makers (and charger cos) not trying to do much about it (and grid cos not caring), than a technical issue. The benefits (especially if V2G) are quite significant.
I doubt any car owner will say no to earning revenue from something that costs them almost nothing. The problem is more of "how do we get there at scale". (Disclaimer, I studied this topic in my thesis.)
As an example, let's say a 2 year old car is only worth 80% of an identical brand new car. The old car was bought for $50k at new, leading to a expected depreciated value of $40k. But since manufacturing has become more efficient a brand new car of the same model can be had for the same $40k. Nobody would be willing to buy the 2 year old car at the same price. You'd probably have to charge only $32k [0]. But then it looks to you as if it has depreciated 36%.
The question is how much new electric cars will fall in price in the future. And if they continue to fall, at some point the dollar value of the depreciation will be too small to care about.[1]
0: $32k = 0.8 * $40k
1: E.g. if a new car is $10k, $3600 in depreciation over two years is annoying, but not a big deal.
Considering how expensive residential batteries are and how quickly EVs depreciate, I think soon it'll be cheaper to get a used EV as a cheap source of cells that accidentally happens to be able to drive itself around.
Imo V2G, and V2H is unnecessary and add too much complication, I think for the future, solar inverters already have the necessary hardware and certifications to be able to take power and safely connect to the grid - something that requires different hardware and standards compliance in basically every country (yes even within the EU).