San Diego Gas and Electric Moves to reduce PV payment for NEM 1 and 2 customers

[cj5orion]

And then there's that fee every month about getting your service from some other provider . Far as I know,in the coastal areas,there are no other providers! Yet we pay for it,this "opportunity" to go to another provider sometimes will cost 2-3 hundred/month,when your actual electric bill would the same at 2-3 hundred !!!!!

THIS...Is one of the greatest BS "provisions" I have ever seen !!!
I'm in one of those coastal areas and,yes,there are no other "providers"...So...where does that $ 2-$400 go ???

 

[AntronX]

641 cycles, 2 years, is fine for a battery that lasts 3000 or 6000 cycles.
I think the cells cost around $0.05/kWh, maybe cheap used EV batteries can be much less. BMS and inverter cost will put a floor on it.

But I don't think you're arbitraging import vs. export prices, looks like off-peak vs. peak export prices. Then have to consider your cost to produce, which I put around $0.025/kWh (DIY) or $0.10/kWh (turnkey), amortized over 20 years.

Instead of exporting for several hours around Noon and getting $0.025 credit, you store in batteries and export only around 7:00 & 8:00 PM when you get $0.30.
Use power stored in batteries whenever consumption exceeds production, during sunny seasons.
Off season, when daily production is below consumption, save your battery storage for 4:00 to 8:00 PM or other peak rate times, use the credits saved to buy power for $0.19

That lets you get 1.5 kWh back for each kWh exported. You'll be limited by kW of battery inverter. At one point I think PG&E allowed battery inverter to be 2x the rating of PV inverter, not sure now. If 120% rule applies to your installation that will be a limit.

Looking at the price chart again I notice that self consumption price arbitrage provides much higher price spread versus export only. Storing solar that would otherwise cost $-0.025 to export and then self consuming during 4 - 8pm would net $0.445 profit. That would take DIY battery payback down to 339 cycles.

 

[zanydroid]

Looking at the price chart again I notice that self consumption price arbitrage provides much higher price spread versus export only. Storing solar that would otherwise cost $-0.025 to export and then self consuming during 4 - 8pm would net $0.445 profit. That would take DIY battery payback down to 339 cycles.

Exactly. This is kind of under appreciated when the expansion of superpeak comes up. It gets better if you are an annual net consumer because you can ship that excess power out during summer superpeak and consume it back at winter off peak rates.

339 cycles is optimistic though. You need a UL9540 system to be allowed to add storage to your NEM install. And secretly changing it will be super obvious due to the change in your power import/export over time.

 

[hwy17]

Isn't battery exporting disallowed unless you're in a VPP?

 

[AntronX]

339 cycles is optimistic though. You need a UL9540 system to be allowed to add storage to your NEM install. And secretly changing it will be super obvious due to the change in your power import/export over time.

Convert to battery offgrid inverter and focus on self-consumption instead of export. At these prices grid export no longer makes sense. Maybe return to grid-tie when UL9540 batteries get to DIY price level.

 

[fafrd]

Looking at the price chart again I notice that self consumption price arbitrage provides much higher price spread versus export only. Storing solar that would otherwise cost $-0.025 to export and then self consuming during 4 - 8pm would net $0.445 profit. That would take DIY battery payback down to 339 cycles.

Precisely. With where rates will be headed under NEM 3, the best strategy is to avoid / minimize export while offsetting consumption during the day (which means capturing excess energy that would otherwise get exported into a house battery) and then to use that stored energy to offset consumption overnight.

You only want to allow energy to export in the afternoon once the house battery is charged and it would otherwise be wasted.

Grid-tied ESS and a larger battery allows you to export any excess energy between 7-9pm when the grid pays the most but it’s really not clear whether there is any actual payoff for that extra effort and cost.

The rules for how compensation for overgeneration at annual true-up under NEM 3 are not yet clear but it is unlikely they will allow you to earn more than Net Surplus Compensation Rates for any annual overgeneration (as is the case under NEM 1.0 and NEM 2.0).

What throws things off under NEM 3 is that all NEM 3 installs should significantly overgenerate (since they can be sized to produce 150% of annual consumption in kWh).

So if we assume you perform unnatural acts to export all of your overgeneration from 7-9pm at credit rates close to near-peak, that annual Overgeneration credit of ~50% x $0.32 is unlikely to be compensated at more than 1/4 that level (~50% x NSCR which is currently $0.08).

If you consume an increased amount of peak-period energy during winter months when solar generation wanes (for example from electrical heating), it’ll no-doubt pay off to invest in a more expensive system / battery to export only during 7-9pm over summer months.

But for those with relatively flat consumption through winter months, just avoiding overnight consumption with a minimum-sized battery sized to capture that amount of energy is likely the quickest path to break-even…

Will need to wait for the first NEM 3 true-ups a ~year from now to understand how it all works…

 

[fafrd]

Exactly. This is kind of under appreciated when the expansion of superpeak comes up.

It’s actually not ‘expansion of super peak’, it’s the ‘return of near-peak’ (mostly shifted to jack up early morning prices before solar generation has kicked-in).

It gets better if you are an annual net consumer because you can ship that excess power out during summer superpeak and consume it back at winter off peak rates.

There should be no/few annual net consumers under NEM 3 since they allow you to generate 150% of annual consumption.

So it’ll only be those whose consumption increases over winter months when solar generation is waning who will have an incentive to maximize export credits over winter months.

If you are sized at 150%, you’ll be able to generate about ~75% of winter consumption assuming flat consumption, which will be offset by summer / spring / fall export credits even at the paltry ~25% of winter off-peak rates.

If you consumption doubles during e winter months, however, you’ll need to export as much of those excess summer / spring / fall kWhs during premium hours of 7-9pm to generate enough NEM credit to offset that increased wintertime consumption…

339 cycles is optimistic though. You need a UL9540 system to be allowed to add storage to your NEM install. And secretly changing it will be super obvious due to the change in your power import/export over time.

Are we talking about modifying a legacy NEM 1 / 2 system or building a new NEM 3 system?

 

[Hedges]

Isn't battery exporting disallowed unless you're in a VPP?

I think we're allowed to store PV production in battery and then export from that.
We're not allowed to store grid power in battery for later export.

Or did something about this change under NEM 3.0?

 

[hwy17]

I think we're allowed to store PV production in battery and then export from that.
We're not allowed to store grid power in battery for later export.

Oh so just no literal arbitraging grid power back and forth. That would make sense too. I don't know the rule in detail and I stopped following NEM programs closely when I decided to go bootleg with my system.

 

[fafrd]

Oh so just no literal arbitraging grid power back and forth. That would make sense too. I don't know the rule in detail and I stopped following NEM programs closely when I decided to go bootleg with my system.

What exactly is it that qualifies you as an ‘Anti-Solar Enthusiast’???

Or by ‘Solar’ are you meaning ‘mainstream Net Energy Metering solar’?

 

[hwy17]

What exactly is it that qualifies you as an ‘Anti-Solar Enthusiast’???

Or by ‘Solar’ are you meaning ‘mainstream Net Energy Metering solar’?

Deep pessimism about the value of solar as a technology. I would rather humanity put our effort into building things we can actually pass down to our children, like nuclear plants, rather than this disposable stuff that they will only inherit in the form of fuller landfills.

As the fruit of the fossil fueled system that produces it though, it makes a fun hobby. And it's the best thing for off grid. I think we are wasting our temporary endowment of these fossil fuels by driving people like me to go off grid by through bad energy policy when I'm actually on the grid.

If we had cheap plentiful grid nuclear power I probably would have picked a different hobby for in the first place, but in this reality I am incentivized towards this one.

 

[AntronX]

Deep pessimism about the value of solar as a technology. I would rather humanity put our effort into building things we can actually pass down to our children, like nuclear plants, rather than this disposable stuff that they will only inherit in the form of fuller landfills.

I mostly feel the same except pessimism about solar. I see it as transition technology toward more space efficient nuclear in the next 100 years. But right now wind/solar/battery is politically acceptable. I am optimistic that once fossil fuel and anti-nuke greens die off, the next generations will fully embrace nuclear power. You don't have to look far - look at China. They are going ahead with nuclear and closed fuel cycle using breeders after 2050. They will make nuclear cheap the same way they have done with solar via mass production.

 

[zanydroid]

Convert to battery offgrid inverter and focus on self-consumption instead of export. At these prices grid export no longer makes sense. Maybe return to grid-tie when UL9540 batteries get to DIY price level.

That doesn’t work for cross season credits which is what I need for my individual situation. YMMV.

Are we talking about modifying a legacy NEM 1 / 2 system or building a new NEM 3 system?

Modify NEM1/2 since that is the only system that gives you meaningful cross season credits.

In both cases the change from grid tie to storage with arbitrage is likely detectable, with the difference being that it would be much more egregious in NEM1/2 since in NEM3 there would only be export when the batteries are full (since you might as well get some cents instead of nothing)

Oh so just no literal arbitraging grid power back and forth. That would make sense too.

Yup, PG&E has spilled a lot of ink spelling out rules to try to prevent you from doing this. It’s a couple pages worth, covering like 10 different allowed/disallowed configs and ways to monitor you for compliance.

 

[zanydroid]

With regards to nuclear vs solar, note that even clean fusion is may well have ongoing environmental impact from cooling footprint.m

It does suck that these solar panels are going to end up being bulky waste. Maybe there can be solar powered robot shipping vessels in 30 years taking these to parts of the world that can still use them after 30% degradation

I also think with low density suburban lifestyle in the US, using rooftop solar to offset energy usage is consistent with mitigating the land impact of living that way.

 

[Hedges]

Modify NEM1/2 since that is the only system that gives you meaningful cross season credits.

In both cases the change from grid tie to storage with arbitrage is likely detectable, with the difference being that it would be much more egregious in NEM1/2 since in NEM3 there would only be export when the batteries are full (since you might as well get some cents instead of nothing)

Adding storage to NEM 1/2 system is acceptable, nothing egregious about that. But PTO advisable.
You would want to store PV to batteries during low times, export during high times, to maximize credits.
I haven't yet, generally finish up the year with credits to spare. Even started running electric heat and A/C during peak times to be comfortable and hopefully only reduce what I leave on the table. Goal is to never buy electricity.

Got the has furnace working again - thought it was flame sensor, but was just invisible contamination on PCB. I think - IPA wash fixed it.
This lets me use gas during peak electric rates if I project to need more heat than electric credits cover.