Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register
  • The latest TMC Podcast (#14) is now available on YouTube and all major podcast networks. We covered FSD Beta's exciting v11 update, Enhanced Autopilot coming to the U.S. and Canada, and more!

Can I add more solar with PG&E?

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
Have 8.16 kw system with 3 powerwalls. For all of 2020 and 2021, I used about 16 MWh each year. The previous years, I also used about that much but it is just a coincidence. When the pandemic hit, we stopped driving to work and started working at home. We started using our AC in the summer which we almost never did before. It was just about the same offset as the charging we were no longer doing on our Tesla.

When I signed up for Tesla solar, they originally suggested a 16 kw system after we uploaded our PG&E bill. It would have been overkill. I decided on half that and it was enough to leave about $300 in credit unused at true-up.

But I'm about to start driving to work again but my wife isn't which means we're now be using the AC in the summer AND charging so my usage is going to go up about 40%. On top of that, we're going to be adding heat pumps for heating rather than using propane and replacing our propane water heater with a hybrid, but that's probably a year away. I want to get more solar installed before NEM3 is voted on and goes into effect.

So how does this work? My PGE bills for the last 16 months net out to about nothing except the NBCs which squeaked past the $10 minimum billable. So I owed $40 at true-up.

Will I be allowed to add more solar but PG&E says no to increased exports even if I end up using them? Or can they deny permission to operate entirely? What steps do I need to take to ensure that I can install more solar now so my energy needs that are about to change but haven't quite yet are met and do it before NEM3 goes into effect?
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,271
2,659
East Bay NorCal
Good luck man...

PG&E requires solar installs to complete this form when they apply for PTO and system design approval. They're primarily looking at your prior annual usage, but you have the option to attest to future increase in planned usage. The resulting approved solar generation cannot exceed more than 110% per PVWatts data.

I didn't have an EV or charger at the time I applied for my install in 2019. But for (8) on this form, I put in an extra 3,400 kWh (10,000 miles x 340 watt hour per mile). PG&E inspected my house and told me they were nixing this since they didn't believe I was going to get an EV.

But PG&E let h2ofun build like 200% of his annual usage, so i don't know wtf PG&E's motive is for this form.

1646531975998.png
 
  • Like
Reactions: buckets0fun

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
I left out a critical piece of information. I mentioned that I left $300 in net credit on the table but I was not a net exporter.

My 2021 total house consumption was 16.26 MWh, but my solar generation was 14.46 MWh. My previous two years to that were in the 14 MWh range so all PG&E will see is that my generation in 2021 was just about equal to my consumption before I got solar but my consumption was 2 MWh higher after getting solar even without charging because we used the AC a lot.

What will they look at for previous years usage since my poweralls completely hide how much I actually used. i.e. all self consumption is subtracted from their view.

My typical exports are about half of their estimated PV generation so if it's just a matter of them not allowing more exports than their current estimates, then I don't care as I'll never hit that even with the extra 4.8 kw system. But if they can reject the install altogether, then that will suck.
 
If they tell you the limitation is the transformer and that upgrade is expensive, you can always just do a non export system with just a building permit. You may need to notify PG&E per the NEM agreement but if configured behind the meter with no export PG&E permission may not bexpensive, The installer may need some expertise installing CTs in the correct location.
 
So how will PG&E now my previous year usage given that it's net less than zero from the grid? Do we just tell them what it is based on Tesla's GW2 usage?
Will they nix the entire install or will they just limit credit for my exports?
Just tell them on the form that you have increased demand as you plan to be using an EV with an increased usage. @holeydonut's personal torturous experience with PG&E notwithstanding, we put in for 150% of prior baseline due to planned purchase of an EV with no issues. With Covid, they have seen lots of change in usage patterns. You won't be the first or last to be powering your home with additional electrical demand AND driving more.
 
  • Informative
Reactions: sorka

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,657
18,779
Riverside Co. CA
Just tell them on the form that you have increased demand as you plan to be using an EV with an increased usage. @holeydonut's personal torturous experience with PG&E notwithstanding, we put in for 150% of prior baseline due to planned purchase of an EV with no issues. With Covid, they have seen lots of change in usage patterns. You won't be the first or last to be powering your home with additional electrical demand AND driving more.

My personal feeling (with no verification whatsoever), is that both @holeydonut and @h2ofun 's experiences are at either ends of an extreme (at the ends of the curve) with @holeydonut 's being "the utility wont let you do anything" and @h2ofun 's being "sure, do whatever you want".

Everyone else is somewhere between their two very different experiences, so my advice would be not to expect either one of their experiences, but something in the middle.
 

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
This is the list of additional electrical usage we plan on but I haven't done the calcs yet:
  1. Convert propane water heater to hybrid electric.
  2. Replace propane dryer with heat pump dryer.
  3. Replace 4 ton and 5 ton HVACs with mutli zone heap pumps (48K BTU and 60K btu from propane currently).
  4. Increase car charging from about 5K miles per year back up to 30K miles.
The extra 4.8kw system won't actually cover all of the increases but I don't want to overcommit this early when it could take a few years to get the propane appliances all cycled out.
 

h2ofun

Active Member
Aug 11, 2020
3,702
893
auburn, ca
My personal feeling (with no verification whatsoever), is that both @holeydonut and @h2ofun 's experiences are at either ends of an extreme (at the ends of the curve) with @holeydonut 's being "the utility wont let you do anything" and @h2ofun 's being "sure, do whatever you want".

Everyone else is somewhere between their two very different experiences, so my advice would be not to expect either one of their experiences, but something in the middle.
My experience I worked with an experienced 3rd party, and I trusted knew what could get approached, even though I thought no way. They told me if at the end it was not approved, they would have to modify, remove, etc at their own cost. So, IMO, go for the gusty as I did. No never know what you will get back. And depending on what year you want to compare, either I am like 100% of usage, or maybe 1000% of usage. :)
 
One comment on the switch to heat pump dryers is that I would encourage you to look at the cycle time for the washer loads that you expect to have (wet lbs) and consider if that works for you. The HP dryers work great if you do a load a day, but less so if you do three in a row, even with a long cycle on a HE front loader...

All the best,

BG
 

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
One comment on the switch to heat pump dryers is that I would encourage you to look at the cycle time for the washer loads that you expect to have (wet lbs) and consider if that works for you. The HP dryers work great if you do a load a day, but less so if you do three in a row, even with a long cycle on a HE front loader...

All the best,

BG

Yup. Done the research. Also easier on clothes. But the bottom line is I refuse to live on fossil fuels even if it comes with some minor inconveniences.
 
  • Like
Reactions: BGbreeder

h2ofun

Active Member
Aug 11, 2020
3,702
893
auburn, ca
One comment on the switch to heat pump dryers is that I would encourage you to look at the cycle time for the washer loads that you expect to have (wet lbs) and consider if that works for you. The HP dryers work great if you do a load a day, but less so if you do three in a row, even with a long cycle on a HE front loader...

All the best,

BG
I just go with 100% electric, much easier
 

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
Using the CSI EPBB calculator for a 340 watt 14 module system using the Tesla inverter, it's roughly 6,789 kwh per year additional generation.

Additional sources of usage:

7860 kwh of heat pump heating - HVAC conversion of 4 and 5 ton heating units to heat pumps. We hardly heat the bedrooms so the 5 ton heat pump would be what is run 99% of the time. 4 months x 30 = 120 days for 12 hours with HSPF of 11 = 7860 kwh / year of heating. The calculator doesn't have my location exactly but it does have Sacramento which is a similar climate. I have a quote from a contractor for a 4 and 5 ton system replacement.
394 kwh from heat pump clothes dryer - 0.54 kwh per load x 2 loads per day.
4560 kwh - Electric water heater. If I can find a hybrid water heater that will fit in our cabinet, then that would be 924 kwh / year.
2982 kwh from additional EV driving - 21000 miles additional driving(260 mile roundtrip twice a week) at 284 wh / mile (rated) for Model X Plaid which is 5964 kwh of additional driving. Half of the charging would be done at work so 5964 / 2 = 2982.

Total additional estimated usage is 15,796 kwh so basically double. I'd order a 9.6 kw but don't have the roof space unless I install north facing but the ROI for north facing production doesn't pencil out for me.

So one question I have is will PG&E require that I already have the extra sources of usage already installed or is it just a matter of providing estimates and quotes from installers.

Lastly, why does PG&E even require justification? Say you just flat out lie about it and install a ton of solar so that you're a net generator. You're basically giving that electricity to the grid. I guess you'd wholesale rates of like 3 cents at true-up. It's too bad there's no way to just sign that away and say you don't want any wholesale payout at trueup and if you've installed too much solar, PG&E is basically getting excess generation for free.
 
Last edited:
Have 8.16 kw system with 3 powerwalls. For all of 2020 and 2021, I used about 16 MWh each year. The previous years, I also used about that much but it is just a coincidence. When the pandemic hit, we stopped driving to work and started working at home. We started using our AC in the summer which we almost never did before. It was just about the same offset as the charging we were no longer doing on our Tesla.

When I signed up for Tesla solar, they originally suggested a 16 kw system after we uploaded our PG&E bill. It would have been overkill. I decided on half that and it was enough to leave about $300 in credit unused at true-up.

But I'm about to start driving to work again but my wife isn't which means we're now be using the AC in the summer AND charging so my usage is going to go up about 40%. On top of that, we're going to be adding heat pumps for heating rather than using propane and replacing our propane water heater with a hybrid, but that's probably a year away. I want to get more solar installed before NEM3 is voted on and goes into effect.

So how does this work? My PGE bills for the last 16 months net out to about nothing except the NBCs which squeaked past the $10 minimum billable. So I owed $40 at true-up.

Will I be allowed to add more solar but PG&E says no to increased exports even if I end up using them? Or can they deny permission to operate entirely? What steps do I need to take to ensure that I can install more solar now so my energy needs that are about to change but haven't quite yet are met and do it before NEM3 goes into effect?
Tips for the hybrid water heater. I installed one last year when I switched my nat gas appliances to electric. Be prepared for noise when it's running in efficiency mode (heat pump mode). Also consider ducting air to and from the water heater. I didn't move the water heater: the hybrid is where the gas one was. That means in the laundry room near the master bedroom. It's loud, but it's in a closet within the laundry room and I walled the closet with thick sound absorbing foam (the outer layer has the angled surface like a recording studio). That works great for reducing the noise and has the water heater near the main use -- the master bathroom -- so there's less heat loss through transport. By ducting to and from the attic I increased the throughput greatly. For most of the year I have hot air in the attic from hot Alabama weather fed into the intake to provide ample heat for the water heater to push onto the water. I vent it back to the attic to have a zero effect on air pressure in the house. I tried exporting it to the living quarters but it made a really cold zone in an otherwise controlled temp house.

As far as solar goes, the hybrid water heater is awesome. My inverter can do 9 kW continuous power. So when I have appliances running simultaneously, the hybrid water heater is rarely a factor is pushing my total load beyond 9 kW (forcing my solar inverter to pull from the grid). The same by the way with my variable speed heat pump. Even in the Alabama summer it rarely goes into full mode and pulls 4 kW because it constantly runs in the summer (keeping the house cool continuously without having to play catchup every 15 minutes or so).
 
  • Like
Reactions: sorka

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top