Planning new off grid solar system for mainly charging an EV

[ElliottB]

Hello,

I've never done any solar experience. I just watched some videos and now am trying to come up with a system. If anyone has advice on the size and what to buy, I really appreciate it.

Few facts:
1. I live in Southern California. I have a two car garage on which I want to install solar panels. The garage roof is under the sun almost all day.
2. I have Hyundai Kona Electric (64 kwh battery).
3. I want to charge solar system battery during the day and want to charge my EV during the night. I want to charge 10-15 kwh every night.

Question:
1. How much watt solar panels should I have? I was considering 600w+.
2. How much watt inverter will do the job? 2000 or 3000 or even more?
3. What kind of battery should I buy? I'm not sure I can build a battery like Will did in one of the videos. I was leaning toward Battle Born. And, I still don't know how much battery I need to buy to save and charge about 15kw everyday.

I appreciate any comments. Thanks

 

[gnubie]

How much roof space do you have available (sq metres, sq feet, what ever you prefer), not forgetting accounting for anything that penetrates the roof such as vents? That will tell you if you have any possible chance of that 10-15kWh / night without dipping into the grid.

 

[ElliottB]

Thank you for the response! Roof space is about 20ft x 15ft. Nothing is on the roof. All areas are quite good with the sun.

 

[gnubie]

Using decent panels, about 200W sqm, that gives you in the vicinity of 5kW peak if you coat your roof in panels so at least that aspect of what you are trying to do is possible even considering off angle, poor orientation etc. You could probably get away with less panels, but you'd need to do a proper survey of the insolation for your garage roof. There are links to insolation maps in the FAQ section of the forum. Don't forget about rainy days etc. 600W would never achieve the production levels you need. 15000/600 = 25 hours of optimal sunlight.

The rest of what you are asking for is all out of my comfortable experience but if you went with a 48V battery to keep the current on the DC side sane you'd need a battery that could accept 100 amps continuous charge current without degrading to be able to capture the full capability of a 5000 watt array.

If you used batteborn 12v 100AH batteries you'd need approx 12 of them, and that's running them completely flat on each cycle so you probably don't want to do that to extend their lifetime. The BB 100AH has a max charge rate of 100 amps and can be used in a maximum of 4 in series. 12 batteries could be arranged as 3 parallel sets of 4 in series (4 to get 48V) and know that they'll get charged at around 33 amps peak which will help extend their lifetime. IMO, you'd really want 16 to get to that 15kWh figure, and not take the batteries to full discharge on each cycle.

When it comes to the inverter you are probably going to want an inverter capable of 220VAC to get 15kWh into the car, depending on the hours you will actually be charging. You'd have to check the capabilities of the car to see what voltage it will accept but highly likely it will accept 220VAC. A 2000W inverter would be able to provide 15kWh to the car in about 8 hours, but that would be running the inverter at 100% for an extended time, usually best to avoid that situation so a 3000W pure sine inverter seems a good starting point.

 

[HRTKD]

When it comes to the inverter you are probably going to want an inverter capable of 220VAC to get 15kWh into the car, depending on the hours you will actually be charging. You'd have to check the capabilities of the car to see what voltage it will accept but highly likely it will accept 220VAC. A 2000W inverter would be able to provide 15kWh to the car in about 8 hours, but that would be running the inverter at 100% for an extended time, usually best to avoid that situation so a 3000W pure sine inverter seems a good starting point.

This is similar to what I was going to respond with.

ElliottB, if you use a 110VAC inverter, it will take a long time to charge the car. I have a Nissan Leaf with the 62kWh battery. If the car's battery was at 20%, 110vac would take fifteen or more hours. I'm guessing here because A) the battery usually doesn't get that low and B) I don't use 110 at home, I have 220.

I've read a few posts (not just here) that say that the cost to implement a system big enough to charge an EV isn't economical. Calculate how much it actually costs to charge your car using power from the utility. Charging my prior EV - also a Leaf - was dirt cheap, like $5, but it had a smaller battery. Then calculate the cost for the system you need. It's not going to be cheap! Like more than $6000. That's a lot of charges.

Also consider that charging an EV when there is still 80% SOC left may not be in the best interest of your EV's battery. However, your battery and your car's battery manager may not have a problem with it. Older Leafs didn't like to be charged in that manner