The best way to install solar panel with EV

[kevinpal]

With all the hassle of renting, hauling, scheduling, and cleaning up trenchers, I finally just broke
down and paid 3 grand (free delivery) for my own, to be used at my convenience. This is 18 inch,
but now a 24 inch is the same price. Mine was not self propelled, but I fixed that with a winch
which pulls it along just fine. Bruce Roe

Thank you for the information, bcroe,
The ground is concrete, so I think I would avoid this rout. Destroying existing concrete and pouring new one cost too much.

[kevinpal]

Well, that makes it more expensive to consolidate the two meters. Thanks for the plot plan.

There is a NEM tariff with SCE that allows you to aggregate two meters with contiguous parcels. I an using it on some commercial property I have on SCE meters in Hermosa Beach. It doesn't save me anything on the fixed charges but at least my solar generation credits offset most of the charges on the other account. Look on SCE's website for Virtual Net Metering.

As to the original question. Perhaps your installer gave you an estimate of annual production. I would guess in perfect conditions you might generate between 6,000 to 7,500 kWhrs per year which will not offset your consumption. To see what your existing system might produce and model what additional solar might contribute go to PV Watts. Do you have more south facing roof area on either building?

I thought I could produce more. The solar company estimated around 9000kWh, I got about 10 proposals and their production ration was 1.6-1.65. Base on the energyage website, the production ratio is 1.4-1.6 in CA. I think VNM is the way I should go. is there monthly fixed charges for that? Is the credit 1-to-1 reduction in their energy bills? Do you know how long VNM under NEM2.0 is grandfathered at this point?

[Ampster]

I thought I could produce more. The solar company estimated around 9000kWh, I got about 10 proposals and their production ration was 1.6-1.65. Base on the energyage website, the production ratio is 1.4-1.6 in CA.

it all depends on your location and installation parameters. Try PVWatts for another estimate.

I think VNMis the way I should go. is there monthly fixed charges for that? Is the credit 1-to-1 reduction in their energy bills? Do you know how long VNM under NEM2.0 is grandfathered at this point?

VNM (sometimes referred to as NEMV)is a financial method of combining meters under NEM, not a rate tariff. I don't think that concept will go away. You would have to look at the various tariffs to find out about fixed charges. I have been on NEM 1.0 for 5 years and changed the mix of meters on my NEMV billing without triggering a change to NEM 2.0. Originally I had 4 but reduced that to 2. If I add solar to on or both of the others, they will be on NEM 2.0. Some of mine are commercial which have different tariffs so I am not up to speed on residential tariffs with SCE.

[J.P.M.]

I thought I could produce more. The solar company estimated around 9000kWh, I got about 10 proposals and their production ration was 1.6-1.65. Base on the energyage website, the production ratio is 1.4-1.6 in CA. I think VNM is the way I should go. is there monthly fixed charges for that? Is the credit 1-to-1 reduction in their energy bills? Do you know how long VNM under NEM2.0 is grandfathered at this point?

On the annual production question: That 9,000 kWh/yr. sounds possible and maybe a bit conservative depending on array orientation and shading for the array size you mentioned (5.28 STC kW) if the array has a mostly southern azimuth and a reasonable tilt of ~ > 20 deg. or so and not much shading.

FWIW, I'm in 92026 and over a 6 yr. period,, the running 365 day total ave. actual production for my array has been 9,092 kWh/365 day period, max., 9,571 kWh/yr., min.8,715 kWh/yr., std. dev. 195 kWh/yr. from a 5.232 STC kW array w/195 az. and 20 deg. tilt and an ~ 3.5 % average annual shade penalty due to a tree I can't kill. What's your array's orientation ?

As for VNM, sounds/reads like you've got some homework to do. To loosely paraphrase what I believe Ampster has written in prior posts, beware of advice you get from perhaps/likely semi informed and mostly anonymous sources such as you'll find on forums such as this one. That incudes anything I might offer. I'd check what SCE has published and call them with questions that
investigation raises.

[FFE]

Kevinpal, you have a less than ideal solution. SCE nighttime rates for their EV plan are higher than most of their TOU plans. The advantage they offer though is that the usage does not count against your baseline, so it is normally a good deal if one does not have solar. Now with a PV system that covers all of your home use and a separate meter for your EV you are in no mans land. You will pay the minimum charge most months, unless SCE counts your EV meter bill against the minimum charge, and pay the baseline credit on the months you produce more than you will use. The best way to figure this out is to estimate your net usage on a monthly basis, since that is how they bill, and run different options. You will also need to educate yourself on their various rates and how the EV rate and the minimum charge works. I am guessing after hours of crunching numbers, you will extend beyond a five year payback.

I would do this in your situation assuming the non EV part of your garage is powered by the main panel, has at least two circuits going to it and your main panel can handle the load. I would consult an electrician and see if the following can be completed. Have one of the 120 volt circuits switched to a dedicated 240 volt circuit. If code allows it, it can be done without new wires. You would have 3.84 kW charging which is normally enough for 99 percent of EV owners. I am definitely not an electrician and I am sure others will chime in mentioning that a white wire is not allowed to do this, but I have read on forums that there is or was a code approved way of doing this. Hopefully someone can chime in and see if this is possible.

[kevinpal]

Kevinpal, you have a less than ideal solution. SCE nighttime rates for their EV plan are higher than most of their TOU plans. The advantage they offer though is that the usage does not count against your baseline, so it is normally a good deal if one does not have solar. Now with a PV system that covers all of your home use and a separate meter for your EV you are in no mans land. You will pay the minimum charge most months, unless SCE counts your EV meter bill against the minimum charge, and pay the baseline credit on the months you produce more than you will use. The best way to figure this out is to estimate your net usage on a monthly basis, since that is how they bill, and run different options. You will also need to educate yourself on their various rates and how the EV rate and the minimum charge works. I am guessing after hours of crunching numbers, you will extend beyond a five year payback.

I would do this in your situation assuming the non EV part of your garage is powered by the main panel, has at least two circuits going to it and your main panel can handle the load. I would consult an electrician and see if the following can be completed. Have one of the 120 volt circuits switched to a dedicated 240 volt circuit. If code allows it, it can be done without new wires. You would have 3.84 kW charging which is normally enough for 99 percent of EV owners. I am definitely not an electrician and I am sure others will chime in mentioning that a white wire is not allowed to do this, but I have read on forums that there is or was a code approved way of doing this. Hopefully someone can chime in and see if this is possible.

Thank you for you reply.

This is the EV rate I got now.
car_rate.png

This is the TOU home rate
home_rate.png
So TOU super off peak rate is cheaper than EV rate.
But I assume as soon as I get NEM2.0, this rate will change bc this is grandfathered plan.

I am not really understanding my electrical circuit.

Have one of the 120 volt circuits switched to a dedicated 240 volt circuit.

this mean switching 120 volt sub-panel to 240volt?
what do you mean by "code allows"?

The electrician will stop by tomorrow to see what the situation is. I will ask him if he can do that.
Thank you for your advice.

Kevin

[kevinpal]

On the annual production question: That 9,000 kWh/yr. sounds possible and maybe a bit conservative depending on array orientation and shading for the array size you mentioned (5.28 STC kW) if the array has a mostly southern azimuth and a reasonable tilt of ~ > 20 deg. or so and not much shading.

FWIW, I'm in 92026 and over a 6 yr. period,, the running 365 day total ave. actual production for my array has been 9,092 kWh/365 day period, max., 9,571 kWh/yr., min.8,715 kWh/yr., std. dev. 195 kWh/yr. from a 5.232 STC kW array w/195 az. and 20 deg. tilt and an ~ 3.5 % average annual shade penalty due to a tree I can't kill. What's your array's orientation ?

As for VNM, sounds/reads like you've got some homework to do. To loosely paraphrase what I believe Ampster has written in prior posts, beware of advice you get from perhaps/likely semi informed and mostly anonymous sources such as you'll find on forums such as this one. That incudes anything I might offer. I'd check what SCE has published and call them with questions that
investigation raises.

Thank you J.P.M
10 of them facing south, 3 of them facing west and 3 of them facing east. It is 18 deg. I get little bit of shade from the trees when sun rises and goes down.
Yes. I am talking to SCE and solar company about VNM. LIke FFE said I have to figure out minimum charges having EV account.

[FFE]

My idea will only work if you have electrical service to your garage exclusive of the EV meter power and code allows it. For example lights, garage door opener and electrical sockets. If you could dedicate one existing circuit to charging, an electrician could remove the neutral from the neutral bus bar, sheath it in the appropriate color and connect it to an empty slot in your panel in an appropriate slot. In your garage they would sheath the neutral leg in the appropriate color and replace an existing socket with a NEMA 6 dash 20 socket. This might also require disabling other sockets in your garage. Again, consult an electrician.

However, looking at the fact you used less than 300 kWh for the EV. If it were me and I had a 120 socket in my garage I would charge using 120 and forget all this extra work. You could keep the fast charging as needed and plug in every night. 1.44 kW for 7 to 10 hours a day would cover your charging.

[kevinpal]

My idea will only work if you have electrical service to your garage exclusive of the EV meter power and code allows it. For example lights, garage door opener and electrical sockets. If you could dedicate one existing circuit to charging, an electrician could remove the neutral from the neutral bus bar, sheath it in the appropriate color and connect it to an empty slot in your panel in an appropriate slot. In your garage they would sheath the neutral leg in the appropriate color and replace an existing socket with a NEMA 6 dash 20 socket. This might also require disabling other sockets in your garage. Again, consult an electrician.

However, looking at the fact you used less than 300 kWh for the EV. If it were me and I had a 120 socket in my garage I would charge using 120 and forget all this extra work. You could keep the fast charging as needed and plug in every night. 1.44 kW for 7 to 10 hours a day would cover your charging.

Ok. This is way over my head. I will consult an electrician about this. but Thank you for your advice.

[Ampster]

Perhaps @Kevinpal can clarify, but from my understanding of this post, there was no electricity to the garage prior to running the service to the garage to charge the EV.

[J.P.M.]

Thank you J.P.M
10 of them facing south, 3 of them facing west and 3 of them facing east. It is 18 deg. I get little bit of shade from the trees when sun rises and goes down.
Yes. I am talking to SCE and solar company about VNM. LIke FFE said I have to figure out minimum charges having EV account.

You're welcome.

If you're curious or interested, do 3 PVWatts runs, one for each orientation and array size, get the hourly model outputs for each array and combine them by hour for total system non-shade output.

That info may be useful info when you are evaluating which rate plan to choose, particularly if T.O.U. is a consideration, and for checking what the vendors are telling you for output. Shade penalty will be the biggest unknown, but knowing unshaded will probably help with the shading penalty SWAG.

Use 10 % system loss parameter in the PVWatts input rather than the 14 % the model defaults to. You'll understand when you read the help screens.

If you do use PVWatts, just remember it's a model that's dependent on input (GIGO), and that the output is a likely, long term average, non shaded output. It's not a prediction of any short period system output. With input that's a reasonable representation of reality, any year's actual system output may vary by ~ +/- 10 % or so from the model results, any 30 day period +/- ~ 30% or so. See the PVWatts help screens for details. FWIW, I've confirmed for myself that those estimates are reasonable for my situation and application.

[kevinpal]

Perhaps @Kevinpal can clarify, but from my understanding of this post, there was no electricity to the garage prior to running the service to the garage to charge the EV.

There was electricity to the garage prior to running the EV charger install.
I talked an electrician and he said he could wire the EV charger to the main panel through the sub-panel and I can get rid of the second meter.
It is 6 years ago and I really don't remember why this happened. but I guess I was told that I have to get a second account and second meter to get special rate for EV by SCE at that time?
But now it is going to be one account with one meter.

[kevinpal]

You're welcome.

If you're curious or interested, do 3 PVWatts runs, one for each orientation and array size, get the hourly model outputs for each array and combine them by hour for total system non-shade output.

That info may be useful info when you are evaluating which rate plan to choose, particularly if T.O.U. is a consideration, and for checking what the vendors are telling you for output. Shade penalty will be the biggest unknown, but knowing unshaded will probably help with the shading penalty SWAG.

Use 10 % system loss parameter in the PVWatts input rather than the 14 % the model defaults to. You'll understand when you read the help screens.

If you do use PVWatts, just remember it's a model that's dependent on input (GIGO), and that the output is a likely, long term average, non shaded output. It's not a prediction of any short period system output. With input that's a reasonable representation of reality, any year's actual system output may vary by ~ +/- 10 % or so from the model results, any 30 day period +/- ~ 30% or so. See the PVWatts help screens for details. FWIW, I've confirmed for myself that those estimates are reasonable for my situation and application.

J.P.M
Awesome site. Thank you for the information. I am checking now.

[Ampster]

There was electricity to the garage prior to running the EV charger install.
I talked an electrician and he said he could wire the EV charger to the main panel through the sub-panel and I can get rid of the second meter.

Great news. If you have a south facing roof there you could add 10% of your existing capacity without triggering a change to NEM 2.O.
I think your experience is a good reason to not trust any Investor Owned Utility without checking with another source. I made a similar mistake but it only cost me less than $100 but it was a valuable lesson the check and verify my assumptions before I made that kind of decision.

[J.P.M.]

Great news. If you have a south facing roof there you could add 10% of your existing capacity without triggering a change to NEM 2.O.
I think your experience is a good reason to not trust any Investor Owned Utility without checking with another source. I made a similar mistake but it only cost me less than $100 but it was a valuable lesson the check and verify my assumptions before I made that kind of decision.

I believe that's either 10 % of the original system size or 1 kW, whichever is greater.