Solar to charge Spark EV

8814 Views 8 Replies 7 Participants Last post by firehawk72, Mar 14, 2016

gmarcucio

Discussion Starter · Mar 13, 2016

Has anyone looked into charging the Spark with Solar Panels off grid system? I have a shed/small garage I park my Spark in and charge with the L1 120v EVSE. I was thinking if I could fit enough panels on my roof and have a off grid battery system with a inverter and plug my EVSE into that to charge the Spark it would be cool! Has anyone done research on it? Does anyone have the calculations I would need to size the solar panel system?

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rmay635703

· #2 · Mar 13, 2016

This is fairly easy but you need a site survey or at the minimum put in your location to know the minimum number of solar hours you will get various times of year.

Next, you need to know how much juice your car uses. (AKA out of the wall socket not on the road)

Once you have these numbers you will know your peak EV useage and your peak and minimum solar hours.

Then you have a choice, do you have backup car? If so, can you accept not always being able to use your EV in the winter?

If not you need to figure you will get about 60% efficiency getting power into a stationary battery and then into your EV (assuming you charge at night) That number is around 80% efficiency (peak) if you charge the car during the middle of the day.

Then figure the number of watts of solar panels needed at solar minimum and voila, you now know how much oversized your system will need to be to handle year round charging with a handfull of days a year where things just don't work out.

If you do it this way you will need to figure out what to do with the extra power.

Good Luck
Ryan

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Ladogaboy

· #3 · Mar 13, 2016

It's going to depend a lot on your specific area, as sun exposure will change with location and physical setup. The biggest issue I can see with this is that you would need to have at least some sort of energy collector (battery, Tesla PowerWall, etc.) linked to the system. Also, unless your Spark is parked there throughout the day, you'll need to collect at least as much power as is necessary to charge it, because the solar panels will only be producing during the day.

As a thought experiment, saying that you didn't need the Spark during the day and you could link an inverter directly to the EVSE, you would need a minimum of a 4 kW array just to feed the charger. Then, if you could get 8-10 hours of sun exposure, you could theoretically fully charge your Spark in a day. Of course, that's not accounting for losses, so you would probably need to increase those numbers.

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Raymondjram

· #4 · Mar 13, 2016

My guess/estimate would be at least 5 kW, so it can charge its battery at the Level 2 3.3 kW per hour and still have surplus for when the Sun is weaker (cloudy or rain). This can charge the full battery in 4 to 5 hours. If you are willing to wait longer, then you can buy less. Or if your Spark EV has the DC fast charge port (orange cap below the AC port), then you can go as high as 16 kW but it will cost even more.

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bentbiker

· #5 · Mar 13, 2016

You said you are currently charging in the shed @ 120v, so I'm assuming you are currently on grid. Does your utility offer netmetering where you send any excess solar generation to the grid and buy any shortfall when necessary, hopefully buying and selling at the same price? If so, why not use the utility as your giant storage battery with this quite simple process? Without it, it is quite an undertaking to go off grid just for the car and probably makes little sense.

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solar_dave

· #6 · Mar 14, 2016

bentbiker said:
You said you are currently charging in the shed @ 120v, so I'm assuming you are currently on grid. Does your utility offer netmetering where you send any excess solar generation to the grid and buy any shortfall when necessary, hopefully buying and selling at the same price? If so, why not use the utility as your giant storage battery with this quite simple process? Without it, it is quite an undertaking to go off grid just for the car and probably makes little sense.

There is the truth of the matter, If you are going to invest in enough panels to meet you peak charging needs you might just as well grid tie. In California I hear this especially lucrative in that high dollar watts sent to the grid in the day equate to a $ credit and low cost watts at night can then be purchase for opportunity loads like water pumping, laundry and of course car charging.

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gmarcucio

Discussion Starter · #7 · Mar 14, 2016

I live in New York state. The Spark EV isn't offered here but I went through hoops to get one and absolutely love it!!! I already have a 6.3 Kw 26 panel grid system on my home roof that I lease from Solar City. I just like tinkering and thought it would be cool to cover my shed with panels and charge the Spark. I have been wanting to build my own system just as a project. How would I be able to add more panels of my own and connect to the grid when I am already connected with Solar City? That's the only reason I wanted to go off grid is I didn't think I could connect into their system.

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bentbiker

· #8 · Mar 14, 2016

gmarcucio said:
I lease from Solar City. I just like tinkering and thought it would be cool to cover my shed with panels and charge the Spark.

Financially, it now makes even less sense since any payback is with savings off your discounted energy costs. However, I certainly understand the concept of doing something as a "hobby" for non-financial reasons.

You say you currently "lease" the system. Is that accurate, or do you merely have a Power Purchase Agreement (PPA) wherein you buy your electricity at a discounted price from Solar City and they have the account with the utility company? If it's a PPA, there might be something in your contract requiring that you buy all your requirement from them. Have you given any thought to asking Solar City if you can buy the system from them? That would certainly avoid a lot of unnecessary duplication, and with a 6.3Kw system, there is a chance you don't need any additional panels to cover all your needs.

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firehawk72

· #9 · Mar 14, 2016

gmarcucio said:
I live in New York state. The Spark EV isn't offered here but I went through hoops to get one and absolutely love it!!! I already have a 6.3 Kw 26 panel grid system on my home roof that I lease from Solar City. I just like tinkering and thought it would be cool to cover my shed with panels and charge the Spark. I have been wanting to build my own system just as a project. How would I be able to add more panels of my own and connect to the grid when I am already connected with Solar City? That's the only reason I wanted to go off grid is I didn't think I could connect into their system.

I never understood the appeal of leasing a system. I installed my own. I add panels anytime I want. The joys of freedom. I would 2nd the idea of being grid connected even though you are considering off grid; otherwise, you will waste most of what you produce.

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