Adding more panels to existing system advice welcome

[Ampster]

...... as a starting point. In our case we chose to go with a plug-in hybrid that can go 45 miles on battery power before the gas engine is needed (powers the car and recharges the main battery at the same time). A 100% EV would need 4x as much power to charge and has a limited range and most EVs have no space left for a spare tire. If you get a flat tire then a flat bed tow truck is needed to take you to a tire store, which is hopefully nearby and open for business and has the tire your vehicle needs. The plug-in hybrids qualify for tax credits and allow for the HOV lanes on the freeways so a good choice at this point with current battery technology.

A hybrid is a great interim step in the transition from internal combustion to electric. In ten years of driving EVs I have had two flat tires, one was my fault and the other was a road hazzard. I have either the EV manufacturer warranty or a good Auto Club towing plan that covers any issues. I feel no need for a spare in the 200,000 miles I have driven my EVs. In that time I figure I have not purchased 10,000 gallons of gasoline for a savings of $40,000. Most of my charging is at home from solar. Those are my economics but I realize it all depends on where you are standing. Current battery technology is sufficient for my needs. I have seen some improvements in that technology but not holding out for any major breakthroughs during my lifetime.

[bcroe]

I feel no need for a spare in the 200,000 miles I have driven my EVs.

Opinions will vary. First thing I have done with a car is replace the mini
spare and bumper jack with a real wheel and frame jack. But my cars
have rather large trunks. Bruce Roe

[MoJ]

Hey folks... resurrecting this thread and going back to the original ?. With NEM3 happening in April, I'm struggling to piece together what to do (if anything).

I'm in a similar boat with the OP. Installed a 27 panel (Axitec 260s, 270w = 7290Kw) system back in 2016 under NEM1. I added an EV and now will be getting hit with a $1500 true up this year in January. We were space limited on # of panels so I knew it was undersized but didn't think I'd go EV as soon as I did.

That said, EV is only using about 2.5Mw per year based on my calcs (and should remain around there). The bigger culprit is lower efficiency.

In 2016 we produced 91% of power consumed. That number has slowly declined to 69% this year. Consumption (outside of the EV) has remained relatively constant between 10.5Mw and 11.6Mw (with EV it's approaching 12.2 this year, and next year I estimate will hit 13.3Mw).

I know the panel degradation has something to do with it - but also we've simply had way more cloudy days these past few years. Generation peaked in 2017 at 9.7Mw and has steadily declined to 8.4Mw this year.

If I simply add more panels to "make up" the lost efficiency can I skirt the 10%/1Kw additional size rule? I can either replace some of the panels with better/more efficient ones, and/or I've now got access to some more space.

*IF* I can get away with that, assuming I replace some of the Axitecs with something like Sunpower with 395w and get to a net 25% increase from where I am today (and just at 10% increase over where I was in 2017, my peak production year) ... in the end, with that additional cost factored in (15 new panels, guestimate $7500 to buy & install), my model shows me being $2k worse off by 2026.

Long story short (way too late, sorry!!!) have I just talked myself into just sticking with what I have until it's time to replace?

Really appreciate any feedback, advice, or things to think about that I haven't yet. You folks (especially J.P.M. ) have been invaluable to me and helped me out a ton!!!

[Calsun]

PG&E pays me $0.03 per kWh with my "agreement" so I am subsidizing all the non-solar customers of theirs. The utility companies want to maintain their monopoly and so they support large solar and wind farms that produce power for their transmission lines and they can continue to upcharge their captive customers. It changes the math as far as payback period for a homeowner installation to what can be saved based on staying in the lowest possible tier.
That said, the rates across the country for electricity has increased by 50% in the past 5 years - because they can.

I would be wary about adding new equipment at this time. My Sunpower inverter died in September and while under warranty they have no replacement units available. I will need to buy a new inverter and pay for it and for it to be installed. It will not be from Sunpower. The payback period also changes if one needs to buy a new inverter every 5-7 years when the one they have fails and parts are not available from the inverter's manufacturer. This would also make the use of microinvertes more appealing.

[J.P.M.]

Hey folks... resurrecting this thread and going back to the original ?. With NEM3 happening in April, I'm struggling to piece together what to do (if anything).

I'm in a similar boat with the OP. Installed a 27 panel (Axitec 260s, 270w = 7290Kw) system back in 2016 under NEM1. I added an EV and now will be getting hit with a $1500 true up this year in January. We were space limited on # of panels so I knew it was undersized but didn't think I'd go EV as soon as I did.

That said, EV is only using about 2.5Mw per year based on my calcs (and should remain around there). The bigger culprit is lower efficiency.

In 2016 we produced 91% of power consumed. That number has slowly declined to 69% this year. Consumption (outside of the EV) has remained relatively constant between 10.5Mw and 11.6Mw (with EV it's approaching 12.2 this year, and next year I estimate will hit 13.3Mw).

I know the panel degradation has something to do with it - but also we've simply had way more cloudy days these past few years. Generation peaked in 2017 at 9.7Mw and has steadily declined to 8.4Mw this year.

If I simply add more panels to "make up" the lost efficiency can I skirt the 10%/1Kw additional size rule? I can either replace some of the panels with better/more efficient ones, and/or I've now got access to some more space.

*IF* I can get away with that, assuming I replace some of the Axitecs with something like Sunpower with 395w and get to a net 25% increase from where I am today (and just at 10% increase over where I was in 2017, my peak production year) ... in the end, with that additional cost factored in (15 new panels, guestimate $7500 to buy & install), my model shows me being $2k worse off by 2026.

Long story short (way too late, sorry!!!) have I just talked myself into just sticking with what I have until it's time to replace?

Really appreciate any feedback, advice, or things to think about that I haven't yet. You folks (especially J.P.M. ) have been invaluable to me and helped me out a ton!!!

From the "Don't shoot me I'm only the messenger", and the "Be careful what you ask for" depts :

1.) Since your system is 7.29 STC kW (not 7,290 kW BTW), and that 7.29 STC kW is what the 10%/1STC kW rule uses, I'm pretty sure you're limited to the 1 STC kW maximum increase in system size.
2.) But, I'd be careful if you do that. Reason: I'm also pretty sure you'll get kicked out of NEM 1.0 if you change/increase the STC size of your system. Reason: That will most likely result in a pyrrhic victory because things are much better under NEM 1.0. That's not to say however (even as unlikely as it may seem at this point) that the CPUC might pull the rug out from under NEM 1.0 at some future point, but you'll go nuts for no reason if you catastrophize about all the "what if" possible futures. FWIW, I'm on NEM 1.0 and tiered rates and intend at this time to stay that way for as long as I can and look for more ways to reduce consumption until or if an EV comes along.
3.) That 8.4/9.7 = 0.87. That works out to a bit less than 3%/yr. decrease from 2017 to 2022 compounded annually. That's well within (under) the annual weather variation for most locations. Besides that, those #'s only apply to only those 2 specific years. You have no way or reason to think the annual decrease has been linear based on only those two years. That comparison is mostly useless for any analysis of output over several years.
4.) Also, I'd bet part of 2017 being your peak production year was partly due to 2017 still being within your system's burn in time which skews the output ratio for those 2 years.

5.) Forget what your actual system annual output numbers are. Run PVWatts on your current system and bump the STC size by 1STC kW to see what the annual LONG TERM AVERAGE output would be under both sizes. The difference is probably +/- 10% or so of what you can expect as a long term difference in average output by adding 1 STC kW to your system. I'd suggest that the model's output ratio will be 8.29/7.29 ~ = 1.14 or so provided rest of the inputs are unchanged.
Just know that if you do that, you can kiss NEM 1.0 behind and that will be the pyrrhic victory I mentioned.

[MGE]

MoJ my guess is the weather has changed from year to year for your fall in production.

I think it my post #12 that shows the production for the years in service and 2021 was actually higher than 2015,17,18,19, and 2020.

My buddy called me up yesterday squawking about the PUC decision on the rate changes and he thinks he's gonna "sneak" more panels onto his system before the 120 day window and he'll be good to go. His Inverter is oversized to accommodate the additional panels but my guess is that he will get a rude awakening by SDG&E if he does what he's proposing.

Don't have a EV, wife has a 2021 Toyota Avalon Hybrid and I drive a 2019 Ford F350 so Im more worried about Diesel prices that Electricity rates.

Im sure we all saw these rate increases coming down the pike when we installed all of our systems when we did.

Some day in the not so distant future us consumers will probably have to pay the utility companies for the "privilege" of doing the right thing by going solar for the environment.
Hopefully I'll be gone by then and my kids can worry about that.

[MoJ]

Thanks for helping to confirm what I knew deep down.

our AC usage did go up due to hotter (and way more humid) weather plus I forgot to mention we moved from a gas oven to induction range, so that’s part of the increase in consumption.

I’m going to model what sticking within the rules and increasing 10% does. If we end up getting a 2nd EV I may also
consider what a 2nd meter for the EVs would do.

Thanks for the reality check guys!