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Does anyone currently have 2 EVs and how much electricity would you need to charge both home and cars? I’m looking into solar panels for my home but don’t know how much electricity I would need.
 

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Does anyone currently have 2 EVs and how much electricity would you need to charge both home and cars? I’m looking into solar panels for my home but don’t know how much electricity I would need.
The Rivian will be our second. We just went through the process to start setting up solar, there are a lot of delays in this process as well for supplies and permitting what normally would be 2-3 months is looking like it will be 6+ months start to finish.

When they scope out the size if you provide them the vehicle electricity requirements and average driving, they can add that into the calculations when they design the system.

For instance I assumed I would be driving about 1000 miles a month and charging at this house around 60% of the time. I used 450 watts per mile and adjusted the 60% to 75% for some buffer and came out with it would add an additional 338 kw a month to my current usage.
 

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Discussion Starter · #3 ·
The Rivian will be our second. We just went through the process to start setting up solar, there are a lot of delays in this process as well for supplies and permitting what normally would be 2-3 months is looking like it will be 6+ months start to finish.

When they scope out the size if you provide them the vehicle electricity requirements and average driving, they can add that into the calculations when they design the system.

For instance I assumed I would be driving about 1000 miles a month and charging at this house around 60% of the time. I used 450 watts per mile and adjusted the 60% to 75% for some buffer and came out with it would add an additional 338 kw a month to my current usage.
Which solar company are you going with? I was looking at Tesla solar panels.
 

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Which solar company are you going with? I was looking at Tesla solar panels.
I'm in SoCal and went with Sunpower by Precis, I went with them because they seemed to have decent panels, fair price and clean installs.

They are still in the permitting process as I need an electrical panel/service upgrade as well as I only have a 100amp service right now.

I can't recommend them until I see how it all comes out.
 

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Does anyone currently have 2 EVs and how much electricity would you need to charge both home and cars? I’m looking into solar panels for my home but don’t know how much electricity I would need.
I recently installed 6.12 kW and it is enough to offset 90% of my electricity including a Leaf and a Model 3.
 

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The answer is... it depends on how much you drive!

Some friends installed an 11kwh system here in the PNW (Seattle, WA). Total electricity cost for the property last year was ~$600 after usage, credits, and incentives. They have 2 EVs (Model 3, Model X) and charge at home 99% of the time, but didn't put many miles on either. There are also 7 people (4 adults, 3 kids) living at the house.

My thought process behind solar is: put in as much as you have space for. I have to imagine that the incremental cost of adding a few more panels is much less than the cost of getting another crew out later and adding more should you need it. And since most places will let you dump excess back in to the grid and give you credits for it, or pay you outright, I don't see a ton of downsides if the incremental extra cost isn't a dealbreaker!
 

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I've got solar, but just one ev so far.

Not really a good case but I'm in Sacramento, CA, but don't always charge at home.

Got a 5.1kw solar system. Last month I produced 1,000kwhs.

If I did fully charge at home, my charging would use up Around 130-150kwh. Thats basic daily driving (around 20 miles). I have an egolf. If I tacked on the Rivian r1t at the same mileage, I would expect 220-250kwh of usage due to the efficiency drop.

That would cover my last monthly bill still with both cars. So, about 400kwh total. However in winter that would not suffice and it'd be hard to plan for it for all months through the year unless you really oversized your system.

These numbers would be highly dependant on your driving and how much solar you can physically put on your house.

Go to energysage.com to get some quotes. Check out your current energy usage with your existing bills.. then tack on some charging usage and try to get that much around peak solar months plus a little extra.

For my egolf, I got about 4 miles per kwh.

Rivian I would estimate at 2 miles per kwh. So driving 10 miles a day for a month is 5 kwh per day times 30 is 150kwh. There's some efficiency looses but just keep it simple, and try to overshoot by 10 to 15% to cover your bills for the full life of solar.
 

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The answer is... it depends on how much you drive!

Some friends installed an 11kwh system here in the PNW (Seattle, WA). Total electricity cost for the property last year was ~$600 after usage, credits, and incentives. They have 2 EVs (Model 3, Model X) and charge at home 99% of the time, but didn't put many miles on either. There are also 7 people (4 adults, 3 kids) living at the house.

My thought process behind solar is: put in as much as you have space for. I have to imagine that the incremental cost of adding a few more panels is much less than the cost of getting another crew out later and adding more should you need it. And since most places will let you dump excess back in to the grid and give you credits for it, or pay you outright, I don't see a ton of downsides if the incremental extra cost isn't a dealbreaker!
I would say whether go big depends a lot on the net metering policy. In Virginia you can only get credit to cover your bill and that is it. Any excess production goes to the electric power company. In other places the price you sell the energy you produce is much lower than the price you pay for it.
 

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I've had my 11.6kw system in NJ since 2017 with 2 EVs all along. In 2019 got a Tesla Powerwall system which represents the photo. With the juice provided by the Powerwall itself at night (not represented in first photo) plus solar I meet 100% of house and driving needs.
2200

2201
 

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I think you are asking the wrong question. How much space do you have for solar? How much would it cost vs how much it would save you? Forget the EV for a moment and look at raw data about generation vs utilization.
 

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I've got solar, but just one ev so far.

Not really a good case but I'm in Sacramento, CA, but don't always charge at home.

Got a 5.1kw solar system. Last month I produced 1,000kwhs.

If I did fully charge at home, my charging would use up Around 130-150kwh. Thats basic daily driving (around 20 miles). I have an egolf. If I tacked on the Rivian r1t at the same mileage, I would expect 220-250kwh of usage due to the efficiency drop.

That would cover my last monthly bill still with both cars. So, about 400kwh total. However in winter that would not suffice and it'd be hard to plan for it for all months through the year unless you really oversized your system.

These numbers would be highly dependant on your driving and how much solar you can physically put on your house.

Go to energysage.com to get some quotes. Check out your current energy usage with your existing bills.. then tack on some charging usage and try to get that much around peak solar months plus a little extra.

For my egolf, I got about 4 miles per kwh.

Rivian I would estimate at 2 miles per kwh. So driving 10 miles a day for a month is 5 kwh per day times 30 is 150kwh. There's some efficiency looses but just keep it simple, and try to overshoot by 10 to 15% to cover your bills for the full life of solar.
Solid Math and Explination
 

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I've got solar, but just one ev so far.

Not really a good case but I'm in Sacramento, CA, but don't always charge at home.

Got a 5.1kw solar system. Last month I produced 1,000kwhs.

If I did fully charge at home, my charging would use up Around 130-150kwh. Thats basic daily driving (around 20 miles). I have an egolf. If I tacked on the Rivian r1t at the same mileage, I would expect 220-250kwh of usage due to the efficiency drop.

That would cover my last monthly bill still with both cars. So, about 400kwh total. However in winter that would not suffice and it'd be hard to plan for it for all months through the year unless you really oversized your system.

These numbers would be highly dependant on your driving and how much solar you can physically put on your house.

Go to energysage.com to get some quotes. Check out your current energy usage with your existing bills.. then tack on some charging usage and try to get that much around peak solar months plus a little extra.

For my egolf, I got about 4 miles per kwh.

Rivian I would estimate at 2 miles per kwh. So driving 10 miles a day for a month is 5 kwh per day times 30 is 150kwh. There's some efficiency looses but just keep it simple, and try to overshoot by 10 to 15% to cover your bills for the full life of solar.
I would just add that if you have net metering the calculation is simpler because the only thing that matters is the consumption through the year. If you you produce more or less in winter vs summer that gets net out.

So definitely check the net metering policy of your energy provider.
 

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I would just add that if you have net metering the calculation is simpler because the only thing that matters is the consumption through the year. If you you produce more or less in winter vs summer that gets net out.

So definitely check the net metering policy of your energy provider.
I work with utilities and install solar in 33 states. Id be happy to help get you all the answers you need that pertain to building the correct system for you home and energy needs.
 

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I would just add that if you have net metering the calculation is simpler because the only thing that matters is the consumption through the year. If you you produce more or less in winter vs summer that gets net out.

So definitely check the net metering policy of your energy provider.
And make sure to check what options your utility allows when going to solar.

In SoCal, SCE forces you into a TOU (Time Of Use) rate tier if you go to solar.
 

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I am soon getting some solar panels installed (at least hopefully). I live in Oregon near Portland. My system is designed at 8.14kw using a local installer. Still waiting on PGE to approve my system so fingers crossed. I don't currently have an EV buy my installer oversized my system because I made clear I would be getting one. I also maximized the Oregon Energy Trust incentive which caps out at a 8kw system, netting a $2400 rebate on my system.

Mostly I think you got most of the information here but obviously nobody is going to be able to size your system on a message board. For instance do you have a good south facing roof line, do you live in California or Wisconsin. Are there any trees other that will block your solar exposure. Find a good local company, they will look at your power bill, estimate any additional energy needs you have, such as charging your EVs then size your system appropriately. Obviously the net metering policies matter too, here if I use less than I produce I get credits but if I don't use them within a appropriate time period they are donated to low income programs.

Last thought. Think hard before using Tesla. They are cheaper (at least nominally) but they have disadvantages:

  • They use string inverters instead of microinverters
  • They only offer specific sized systems 4,8,12 etc kw so if you want 10kw for instance they may not be the best choice
  • Customer service you receive may not be great, they cut resources to sales and service to cut costs
  • They will almost certainly take longer getting your system up and running. I had placed an order while I was shopping around and weeks later I hadn't heard anything from them.
  • The warranties were not as good

Best of luck
 

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I'm in the same boat as jjswan33 & SANZCO2. I've signed a purchase agreement with a local solar company here in Tucson, AZ. I, too, am waiting for my local utility, TEP, to approve our 17kw system (we have two 4-ton ac units and a pool pump). Knowing the requirements of your local utility was a big part of the process for me. For instance, TEP only approves systems up to 125% of current usage for grid-tied systems. Since I, like you, don't know future energy usage with EVs, I went for the largest array allowed by my utility, 125% of current usage. Also, no net-metering here. TEP has an export rate that we are credited for excess energy generation that goes to the grid. Of course, that rate is lower than our rate to buy from the grid when needed. That's just my situation, yours will be different.

While your EV energy usage is unknown, consider upgrading other known energy hogs in your home. I knew going into the solar purchase process that I needed to upgrade our ac units. We had 15 year old, R22, 12 seer, 2-speed ac units. They weren't energy efficient by today's standards, and had a huge energy draw on start up. While we aren't doing a home battery backup at this point, I wanted to be able to add one later. Upgrading to 20 seer, variable speed units reduced our energy usage. The low energy draw on start up of variable speed ac units will work with a future battery backup, if/when I add it.

jjswan33 nailed it with the bullets on Tesla. They are cheaper for a reason. If you haven't already done so, do your homework on the difference between string inverters, optimizers, and microinverters. Timely service is a huge consideration. If your future system goes down, you will want it back up ASAP. Buy from a provider that is known for timely service. Get quotes from and talk to as many local and national providers as you can. Find the provider that checks the boxes on your needs. After all is said and done, you may find that Tesla meets your needs and expectations. Just make sure you have done your research.

Consider having your solar installer run a 60amp, or larger, circuit line for your future EV charger as part of the process. It's one less thing to deal with later.

Also, if you have an HOA, make sure you don't run into issues there.
 
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