Help me understand NEM2.0 (CA) and solar quotes

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Reid

Active member
Joined
Apr 25, 2018
Messages
69
Location
Redwood City, CA
Tesla Owner
Model 3
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Country
#1
Hello! I'm on a PG&E E6 Time-of-Use plan. I understand from solar installers that this is the 'best' plan to be on, having been discontinued in 2016 and phased out in 2022 (so I can keep it until then). The upshot is that peak hours are 1pm-7pm vs 3pm-9pm on the newer plans.

My understanding is that every kWh I generate in a given 'tier' is credited at that rate under Net Metering 2.0 whereas under the original Net Metering plan, 1kWh=1kWh no matter when it was generated or used.

In my opinion, this means that when I generate at peak hours but charge a car (or do the laundry, or whatever) off-peak, I'm effectively getting twice the value (or more) for my generated kWh than I'm using. I'm 99.5% sure this is correct, with me so far? If you have air conditioning maybe this is bad, but for those of us without A/C, it seems like NEM2.0 is actually better than the original plan.

For example, my rates (Tier 1-only, for simplicity):

Winter:
Off Peak: $0.184/kWh
Part Peak: $0.20/kWh

Summer:
Off Peak: $0.167/kWh
Part Peak: $0.244/kWh
Peak: $0.359/kWh

My understanding is that I can put 2.15x more power into an off-peak load (eg, car charging) than I generate during peak hours; each peak kWh generated is 'worth' 2.15x off-peak. ($0.359/$0.167) Correct me if I'm wrong, but this is what I understand and so far everyone I've discussed this with seems on board.

Where it gets complicated is that solar installers quote (from one example) 5.52kW system, with an estimated year 1 production of 7,283kWh. I've gotten this kind of multiple (or in that ballpark) from several installers.

However, when I spoke with one recently, I was pointing out that, because my generation will be all part-peak or peak (at least in the summer), those credits are more 'valuable' than my off-peak charging. We have minimal peak and part-peak usage as we have no air conditioning, but we DO have great southern exposure on our roof and year-round sunshine.

He kept claiming that the year 1 production numbers were very close to what we'd actually see and that it took into account time-of-use generation. He DID admit that our usage, of course, is based on ballpark estimates of what others use in our area, and may not fit our case exactly. That's fine, and I understand that.

I don't understand how the generation number can factor in ToU, though. It seems to me a kWh is a kWh. There's simply no way to factor in the value of a time-of-use credit, unless they're doing some trickery where I'm not ACTUALLY generating 7283kWh, but more like (say) 6000, and the number is being fudged upwards to produce an 'effective' 7000+ given when it will be generated, and when average consumption happens.

So, what says the collected wisdom? If I'm generating 7283kWh over the year.. lets say for argument's sake it is ALL during peak hours, and ALL during the summer, so it's all $0.359/kWh credit rate.. and I consume 0 electricity in peak and part-peak hours, and ALL of my usage is off-peak.. wouldn't that effectively 'buy' me 15,658kWh of off-peak usage (7283*2.15 multiple)? Or am I misunderstanding either how NEM2.0 works, or how these estimated year 1 production numbers are calculated?

thanks in advance.
 
Joined
May 10, 2018
Messages
3
Location
Temple City
Tesla Owner
Model S
Country
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#2
You've got it mostly right.
The estimated 1 year production is the raw kWh production for your system. But because of TOU rates, you can get by with a system that produces less than what you actually consume.

You have to convert it back to dollars as that is how they credit it (I'm with SCE). Using your scenario, if you produced all during peak (7283 kWh x $0.359/kWh), you'd get $2614 in credits while you'd spend $2614 (15658 kWh x $0.167/kWh).
 

Reid

Active member
Joined
Apr 25, 2018
Messages
69
Location
Redwood City, CA
Tesla Owner
Model 3
Country
Country
#3
Thank you for your feedback, that's what I thought.
Well, system is signed for, so we'll see what happens in the real world. I may have to install air conditioning in my house to eat up the excess credits generated :D
 

JGD108

Active member
Joined
Mar 25, 2018
Messages
37
Location
Orange County, CA
Tesla Owner
Model 3
Country
Country
#4
Thank you for your feedback, that's what I thought.
Well, system is signed for, so we'll see what happens in the real world. I may have to install air conditioning in my house to eat up the excess credits generated :D
One tip: be careful to over generate since they will pay you 2-3 cents for extra KWh you produce.
Might be too late now but it's better to not oversize the system because of the TOU scenario you explained.
It's all good in 5-6 years onwards you might be closer to break even production / usage when they change the rules again :)