California Members: NEM3.0 impact on NEM1/2 customers and what to do?

[fafrd]

That’s a whole different story.

I’m supportive of the CPUC final decision (while I was livid about their Preliminary Decision from a year ago).

I’m generally supportive if he idea to mandate that new home construction require homes to be built ‘solar ready’ (pre installed racking mounts, rooftop junction boxes and even home run wiring).

But mandating new home have solar actually installed is Government Run Amuck, especially coupled with ever-less-favorable terms mandated by the CPUC…

Happy I’m not building a new home in California (ever): https://www.greenlancer.com/post/california-solar-mandate

Seems as though Community Solar will be getting a big boost:

‘One path to fulfilling the mandate requirements for new homes, residents can subscribe to a community solar farm instead of installing rooftop solar panels.’

That is a much more sensible and cost-effective solution anyway.

 

[Hedges]

I just wonder what is done with allocation of power from solar farm to consumer, now that power import/export is accounted for by the (second? minute?)

If farm is always producing, and consumers switch their consumption up and down as thermostat clicks, and produced power is allocated across consumers, could be pretty good (for them). Better than rooftop. Basically back to the old way, given an ensemble of consumers averaging out to steady consumption.

 

[natedogg]

For those of us on nem2, will adding storage to an existing PV system force us to move to nem3? I have a 4.5kw enphase system currently. We might try to expand it to 6-7kw before nem3 takes effect, but won't be able to get to the battery storage for a while. We would very much like to stay on nem2 though!

 

[Hedges]

Last we read, adding storage could be done later while remaining on our existing NEM x.0
Also, only paperwork for a PV system, not installation, required before April 14th to have it under existing schedule rather than NEM 3.0
That ought to apply to additions as well as new systems.

It appeared to me the paperwork required was a form to PG&E identifying the equipment and justifying capacity larger than 5kW. Also something like installer's disclosures to customer, not sure what they require for self-install. I've found a couple versions of forms on their site, see what it takes for you to apply for an addition.

 

[solar8484]

Comparing customer value of solar-plus-storage under net energy metering versus net energy billing

Economist-at-large Ahmad Faruqui reviews the customer incentive to install rooftop solar and energy storage under various California rate structures.

pv-magazine-usa.com

Looks like home solar won't make much financial sense even with batteries under NEM3.

 

[fafrd]

Comparing customer value of solar-plus-storage under net energy metering versus net energy billing

Economist-at-large Ahmad Faruqui reviews the customer incentive to install rooftop solar and energy storage under various California rate structures.

pv-magazine-usa.com

Looks like home solar won't make much financial sense even with batteries under NEM3.

About the only worthwhile factoid in that article is that if you planned to install a rediculously-expensive Tesla-Powerwall-based system, NEM 3.0 will make that less attractive than NEM 2.0 did, but that is a tiny fraction of solar customers.

For most of us focused on reducing electrical bills in a sensible way, the math works out very differently and this is yet another article overlooking to mention the key change in NEM 3.0: authorization to generate 150% of annual consumption.

I’ll run through yet again what that means:

You’ll be able to build an array sized at 150% for costs below what it cost your NEM 1.0 brethren to build their 100%-sized array 7-15 years ago.

Some of that savings will need to go into adding a battery sized to offset average overnight consumption. Far many/most of us, that means at least 5.1kWh, 10.2kWh is probably a sweetspot, and 15.3kWh probably captured 95% of potential customers.

Your 150% sized array will produce ~225% of consumption over summer months. You will capture what you need to offset overnight consumption and export the rest at ~13% Off-Peak Rates.

So over the summer you will generate credit of ~125% x 13% = ~16% of what you’ll consume over winter.

During Spring and Fall, you’ll generate ~150% of consumption meaning you’ll generate credit of 2 x ~50% x 13% = 2 x 6.5% = ~13% of what you’d consume over winter.

So heading into winter, you’ll have built up enough export credit to offset ~29% of winter consumption at Off Peak rates.

Over winter months, your 150%-sized array will only generate ~75% of consumption, so you’ll be short by ~25% which will be covered by the export credits you generated over non-winter months.

So the conclusions to take away from the NEM 3.0 rules for most of us are:

1/ You’ll need to build an array sized for the full 150% they’ll allow (which is great because solar panels are cheap and more than 150% of the power they had 7 years ago).

2/ You’ll need an ESS sized to offset as much overnight consumption as makes sense (if you want a larger battery and full backup power, that’s on your, not the CPUC).

Of course, those that consume much more power over winter because of electrical heating, for example, are going to be much more adversely effected by the NEM 3.0 rules and solar may no longer make sense for them.

On the other hand, those who consume more electricity over summer months, Fran air conditioning, for example, will make out like bandits compared to paying full retail for their electrical consumption.

All of these ‘The End Is Neigh’ for Rooftop Solar in California articles are getting old.

The Preliminary Decision would have been a disaster and would have ended Rooftop Solar. The recently-passed Final Decision is much better-balanced and will not.

 

[Zwy]

Comparing customer value of solar-plus-storage under net energy metering versus net energy billing

Economist-at-large Ahmad Faruqui reviews the customer incentive to install rooftop solar and energy storage under various California rate structures.

pv-magazine-usa.com

Looks like home solar won't make much financial sense even with batteries under NEM3.

With a 9.8Kw battery, he certainly won't make it work.

 

[400bird]

All of these ‘The End Is Neigh’ for Rooftop Solar in California articles are getting old.

The Preliminary Decision would have been a disaster and would have ended Rooftop Solar. The recently-passed Final Decision is much better-balanced and will not.

Well said.
It will mean a change in the statewide industry, but it's not dead.

 

[fafrd]

Well said.
It will mean a change in the statewide industry, but it's not dead.

Exactly.

The main issue I see is that existing ESS solutions are not cost-effective enough to make this fly today.

I could install a 150% - sized array for less than $3000 + installation cost, but a UL-listed 10kWh battery would cost me another $3000 and a UL-listed hybrid such as the Schneider Conext XW Pro would cost that much again.

So let’s call it ~$9000 + $6000 install cost = $15,000 for a bare-bones system to offset my electrical bill.

With the 30%!tax credit, that $15,000 drops to $10,500 but I’m only offsetting an annual electrical bill of $1325 which will now be at least $15 x 12 minimum monthly charge = $180.

So break-even would be $10,500 / $1145 = 9 years, right where the CPUC was aiming for. But that’s best-case and must solar installers would charge an additional $5000 for a similar system, driving break-even up to 11.5 years.

But the glide-path offers an additional $0.018 / kWh for 9 years if installing a NEM 3.0 system in year 1. That’s an increase of 72% over the $0.025 base off-peak export rate and means your 50% overproduction which you export will be worth 72% more than the break-even case I sketched earlier.

5-years from now we’ll probably be able to acquire a 10kWh ESS (battery + hybrid) for ~$3000 rather than the ~$6000 minimum it would cost today, but the glide path they have offered over the first 5 years does a pretty good job closing that gap until more cost-effective ESS offerings are available.

 

[Hedges]

Is the export credit looking like 13% of retail?
In that case, absolutely not worth paying installed price of PV for any power you would export.
Might do OK at DIY costs.

Are import/export tabulated on a minute by minute or second by second basis?
If so, you need a battery big enough to average out over the on/off cycle of your appliances, like A/C and dryer heating element.
That is a small battery, could be cost effective. Optionally large enough to avoid drawing from grid at night.

What I wonder is how community solar will be accounted for. If that is spread over participating consumers, so it is rarely if ever credited as export, rather offsets their consumption, that is a win; it is basically net metering.

 

[fafrd]

Is the export credit looking like 13% of retail?

That’s based on the graph indicating 2.5 cents for export over midday hours versus off-peak retail rates of 19 cents.

In that case, absolutely not worth paying installed price of PV for any power you would export.
Might do OK at DIY costs.

I’m not understanding your conclusion. PV costs per W of panel power keep getting cheaper and cheaper. You can install a 150% sized array today for less than you could install a 100% sized array even ten years ago (same number of panels, just 1.5 times as powerful).

Once you can afford to install an array sized to generate 100% of monthly consumption over winter months, who cares what credit you get for export of summer overgeneration? It’s still better than you’d get being totally off-grid?

Are import/export tabulated on a minute by minute or second by second basis?

You need to check the specific specifications of your smart meter, but in general, you should assume instantaneous tabulation (dual-channel). Export tabulated separately from import.

If so, you need a battery big enough to average out over the on/off cycle of your appliances, like A/C and dryer heating element.
That is a small battery, could be cost effective. Optionally large enough to avoid drawing from grid at night.

Your optional battery is the minimum you need. Store up enough daytime energy to offset overnight consumption (and export any excess for whatever credit you’ll get).

What I wonder is how community solar will be accounted for. If that is spread over participating consumers, so it is rarely if ever credited as export, rather offsets their consumption, that is a win; it is basically net metering.

I don’t see how it changes the math unless the community solar also incorporate a big enough battery to offset overnight consumption.

There will be more energy generated at midday Ryan can be consumed (whether single-residence of a community of several residences).

You’ll need to store that excess energy up to offset overnight consumption whether for one residence or several…

 

[Hedges]

That’s based on the graph indicating 2.5 cents for export over midday hours versus off-peak retail rates of 19 cents.

I’m not understanding your conclusion. PV costs per W of panel power keep getting cheaper and cheaper. You can install a 150% sized array today for less than you could install a 100% sized array even ten years ago (same number of panels, just 1.5 times as powerful).

Without battery, or battery full and exporting power, we get 2.5 cents credit per kWh.
Assume someone pays $3/W for an installed system. Amortized over 20 years, that's about $0.075 per kWh produced.
This saves money vs. buying from grid, if consumed without the house and not exported to grid.
But if the kWh is exported, they get $0.025 credit. Then when they import a kWh, they pay $0.19, for $0.165 net charge on bill.
In addition to the bill, it cost them $0.075 to produce that kWh, total $0.24 cost for 1 kWh consumed.
$0.24 > $0.19, would have been better of without PV, just buy from the grid.

Installed 150% of consumption? Consider 1.5 kWh exported, credit $0.0375
Import 1 kWh, pay $0.19, for $0.1525 net charge on bill
PV cost them 0.1125, total $0.2650 for 1 kWh consumed

If export is credited $0.025, you break even with DIY PV, which costs $1/W and $0.025/kWh.
If you pay for installation, total > $1/W, then producing power costs more than $0.025/kWh and you lose money by exporting.

Once you can afford to install an array sized to generate 100% of monthly consumption over winter months, who cares what credit you get for export of summer overgeneration? It’s still better than you’d get being totally off-grid?

Credit of $0.025/kWh is better than nothing (assuming no added fixed charges), better than curtailing production when off-grid system has full battery.

If you mostly use what you produce at the moment of production, oversize PV could be useful because it covers more of peak consumption, saving you from paying $0.19/kWh for those peaks. At the cost of wasting more production for $0.025 credit when your loads are less. With self-install cost of $0.025/kWh produced the point where returns diminish to zero is about when 7 or 8 additional kWh/day of panels saves you from buying 1 additional kWh from grid during your peak consumption. For turnkey install cost of $0.075/kWh, diminishing to zero returns about 2 or 3 additional kWh/day of panels to avoid importing 1 kWh during peaks.

You need to check the specific specifications of your smart meter, but in general, you should assume instantaneous tabulation (dual-channel). Export tabulated separately from import.

I don’t see how it changes the math unless the community solar also incorporate a big enough battery to offset overnight consumption.

Community solar is/was credited to your account in some manner.
If it credits you $0.025/kWh and you are simultaneously charged $0.19, there is little value. Merely break-even if community solar costs $1/W installed, therefore not worth doing.

If, however, 1 kWh of community solar offsets your meter's record of 1 kWh consumption, then you come out ahead.
That could be done under net metering, because 1:1 credit. But what is done under NEM 3.0?


You may or may not want to buy a battery to ride through the night. Where NEM 3.0 will screw people over is loads that toggle on and off.
Consider a PV system exporting 2kW, and a dryer that draws 4kW and switches on/off with 50% duty cycle. Half the time, net draw is 2kW, costing $0.19 x 2 = $0.38/kWh. Half the time net export is 2kW, credit $0.025 x 2 = $0.05. Net charge is $0.14 per hour.
If you have a battery being controlled for zero export, zero import, PV supplies 100% of dryer's consumption, zero credit zero charge.

Continuously variable consumption by appliances would be another approach.
But bolting a battery to the side of the house and attaching CT is a standard product that will work for everyone.
In the end, it accomplishes nothing different from net metering, or aggregating a few dozen neighbors and tracking net import/export for the neighborhood.

I think but don't know that San Jose Power, a virtual power company which sells power to and credits for power from homeowners, might be able to skim the windfall that NEM 3.0 gives the utility. But probably not, will be required to pay transmission costs to PG&E for each house that imports at any given instant.

If a condo complex or apartment building installed a single meter where utility feeds power to the property, and did its own metering of individual units, then it would get the benefit.

 

[fafrd]

Without battery, or battery full and exporting power, we get 2.5 cents credit per kWh.
Assume someone pays $3/W for an installed system. Amortized over 20 years, that's about $0.075 per kWh produced.
This saves money vs. buying from grid, if consumed without the house and not exported to grid.
But if the kWh is exported, they get $0.025 credit. Then when they import a kWh, they pay $0.19, for $0.165 net charge on bill.
In addition to the bill, it cost them $0.075 to produce that kWh, total $0.24 cost for 1 kWh consumed.
$0.24 > $0.19, would have been better of without PV, just buy from the grid.

Installed 150% of consumption? Consider 1.5 kWh exported, credit $0.0375
Import 1 kWh, pay $0.19, for $0.1525 net charge on bill
PV cost them 0.1125, total $0.2650 for 1 kWh consumed

If export is credited $0.025, you break even with DIY PV, which costs $1/W and $0.025/kWh.
If you pay for installation, total > $1/W, then producing power costs more than $0.025/kWh and you lose money by exporting.



Credit of $0.025/kWh is better than nothing (assuming no added fixed charges), better than curtailing production when off-grid system has full battery.

If you mostly use what you produce at the moment of production, oversize PV could be useful because it covers more of peak consumption, saving you from paying $0.19/kWh for those peaks. At the cost of wasting more production for $0.025 credit when your loads are less. With self-install cost of $0.025/kWh produced the point where returns diminish to zero is about when 7 or 8 additional kWh/day of panels saves you from buying 1 additional kWh from grid during your peak consumption. For turnkey install cost of $0.075/kWh, diminishing to zero returns about 2 or 3 additional kWh/day of panels to avoid importing 1 kWh during peaks.



Community solar is/was credited to your account in some manner.
If it credits you $0.025/kWh and you are simultaneously charged $0.19, there is little value. Merely break-even if community solar costs $1/W installed, therefore not worth doing.

If, however, 1 kWh of community solar offsets your meter's record of 1 kWh consumption, then you come out ahead.
That could be done under net metering, because 1:1 credit. But what is done under NEM 3.0?


You may or may not want to buy a battery to ride through the night. Where NEM 3.0 will screw people over is loads that toggle on and off.
Consider a PV system exporting 2kW, and a dryer that draws 4kW and switches on/off with 50% duty cycle. Half the time, net draw is 2kW, costing $0.19 x 2 = $0.38/kWh. Half the time net export is 2kW, credit $0.025 x 2 = $0.05. Net charge is $0.14 per hour.
If you have a battery being controlled for zero export, zero import, PV supplies 100% of dryer's consumption, zero credit zero charge.

Continuously variable consumption by appliances would be another approach.
But bolting a battery to the side of the house and attaching CT is a standard product that will work for everyone.
In the end, it accomplishes nothing different from net metering, or aggregating a few dozen neighbors and tracking net import/export for the neighborhood.

I think but don't know that San Jose Power, a virtual power company which sells power to and credits for power from homeowners, might be able to skim the windfall that NEM 3.0 gives the utility. But probably not, will be required to pay transmission costs to PG&E for each house that imports at any given instant.

If a condo complex or apartment building installed a single meter where utility feeds power to the property, and did its own metering of individual units, then it would get the benefit.

First, I question the $3/kW installed cost, but if that includes battery and hybrid as well as the +50% PV, it may be reasonable.

This would mean 5000kWh of consumption that could be offset with production from a 4kW array could be offset by a 6kW array + 10kWh battery + 4kW hybrid for $12,000. Within 5 years, perhaps, but today probably closer to $18,000.

Second, you keep mentioning import. The point is there will almost never be import. Only over winter months will you be importing ~25% of consumption. March through September you are only going to import when instantaneous consumption exceeds max output power rating of your hybrid (almost never is you spec’d it properly). So the paltry export credits only need to provide enough to offset ~25% consumption over winter.

Lastly, in terms of battery+hybrid cost not yet being where they need to be to for this to add up ($18,000 today rather than $12,000), the glide path helps.

Year 1 NEM 3.0 customers will get an additional $0.018 per kWh for 9 years. That totals to $0.043/kWh or 23% of retail off-peak rates.

Let’s take the example of an off-grid customer who builds an array sized to 100% of wintertime consumption (meaning > 150% of annual consumption).

They spent more on a bigger array.

They needed to spend more on a bigger battery or a generator to get through days of bad weather / poor production.

If they exported their 100% overproduction for $0,025/kWh (or $0.043 if they start NEM 3.0 in year 1), they would get enough credit to more than offset the minimum charge their utility would charge them to stay on grid.

A battery sized to offset overnight consumption will be significantly smaller / cheaper than one sized to go off-grid or for backup power, and that is key.

And on community solar, suggest we take that discussion to a different thread (or at least distinct posts). It’s not clear to me whether you are taking about CCEs or not, but if you are, I can confirm the rules are no different as far as NEM and solar.

 

[Hedges]

First, I question the $3/kW installation cost, but if that includes battery and hybrid as well as the +50% PV, it may be reasonable.

Not "installation", "Installed"
No battery, just turnkey GT PV. This puts it at $2.71/W as of 2020:

https://www.nrel.gov/solar/market-research-analysis/solar-installed-system-cost.html

(I don't understand why "land acquisition" and "transmission line" would be soft costs of residential rooftop install. Probably zero in that case, but "overhead and profit" far higher.)

Second, you keep mentioning import. The point is there will almost never be import.

Without battery, and conventional appliances that cycle on and off, you will export-import-export-import constantly. Unless you install PV near peak consumption. A/C, clothes dryer, refrigeration, stove, well pump ... many things cycle on and off.

This is why I say under NEM 3.0 you need a battery to smooth out at least daytime consumption, match it to day's production so you avoid exporting and then importing minutes later.

And on community solar, suggest we take that discussion to a different thread (or at least distinct posts). It’s not clear to me whether you are taking about CCEs or not, but if you are, I can confirm the rules are no different as far as NEM and solar.

The question is, under NEM 3.0 how will the minute by minute import vs. export pricing be done, if exports are all at community solar and imports are all at consumer homes? Does any of the produced power offset consumption 1:1?

 

[fafrd]

Not "installation", "Installed"
No battery, just turnkey GT PV. This puts it at $2.71/W as of 2020:

That is what I meant (typo fixed).

https://www.nrel.gov/solar/market-research-analysis/solar-installed-system-cost.html

(I don't understand why "land acquisition" and "transmission line" would be soft costs of residential rooftop install. Probably zero in that case, but "overhead and profit" far higher.)

Solar installers making money hand over dust is not part of my calculus. I’m looking at hardware costs and assuming an installation cost of ~$500 per panel as a swag at what should be possible.

Without battery, and conventional appliances that cycle on and off, you will export-import-export-import constantly.

I’ve been staring since day one that NEM 3.0 means you will need a battery sized at least big enough to offset overnight consumption. I’m not sure what he point is if discussing battery-free systems under NEM 3.0…

Unless you install PV near peak consumption. A/C, clothes dryer, refrigeration, stove, well pump ... many things cycle on and off.

This is why I say under NEM 3.0 you need a battery to smooth out at least daytime consumption, match it to day's production so you avoid exporting and then importing minutes later.

You are preaching to the choir. And you need a battery for more than smoothing out daytime consumption. You will need a big enough battery to capture enough energy during the day to offset overnight consumption.

No other configuration pencil’s out.

The question is, under NEM 3.0 how will the minute by minute import vs. export pricing be done, if exports are all at community solar and imports are all at consumer homes? Does any of the produced power offset consumption 1:1?

Under my CCE, import and export totals are calculated by the utility and the CCA merely applied their modified import and export rates to those totals.

So nothing changes compared to being billed by the utility it terms of import and export.

Under NEM 3.0 you are not going to have import versus export changing minute bu minute for 9 months out of the year:

During daylight hours, you will maintain zero import / zero export by charging your house battery using excess solar production. Once the house battery is full, you will begin exporting any remaining excess production.

During non-daylight hours, you will use that energy stored in a house battery to offset consumption, so zero import & zero export until the house battery is drained.

Sized properly, a full house battery will offset non-daylight consumption through late morning the following day, do you’ll basically never have any import as long as your daylight production exceeded average daily consumption.

Only over winter months will there be insufficient production during daylight hours to fully-charge the House Battery (especially on rainy days) and it will only be during those months that the house battery will be drained before the Morning Surge has passed which is the only time you’ll be importing.

But even in that situation, any available solar production will be used to begin recharging the House Battery, do you’ll only be switching between zero-export & zero-import and import as appliances such as coffee makers cycle…

 

[time2roll]

Bless you all in California. Hopefully Florida does not institute such progressive policies in the future.

Not about the state as much as the utilities are threatened and are pushing hard on the regulators to strip away the advantages of having solar.
The fight is real.

 

[GXMnow]

After the federal tax credit, my original 4,800 watt grid tied system net cost was $12,000 which works out to $2.50 per watt to cover everything. That even included drawing up the plans and dealing with all the city and utility paperwork. I know I could have gotten it dome a little cheaper, but these guys did excellent work and the install looks far better than many I have see. There is no visible conduit anywhere, and even in the garage, the routing is clean and professional.

If the credit dropped to just $0.025 per KWH, it would basically never pay off without storage.
Once you do add battery storage though, the whole equation turns upside down. Or in this case, down side up.
Without a battery here with So Cal Edison, an evening 4pm to 9pm KWH now would cost you about $0.45 so any solar produced KWH you can save and use in the evening becomes worth that much. That is the whole point of the new NEM 3.0 rules. It is totally geared to push all solar users to have batteries. Even at today's credit of 25 cents, having to buy it back at 45 cents is a big rip off. I store up over 10 KWHs a day on average. That 20 cents different x 10 = $2 a day saved by the battery. That comes out to over $700 a year. My solar panels produce 8 megawatt hours a year. That is an average of almost 22 KWHs a day, every day. Of course my peak days were over 31, but those are offset by the days I got just 2 to 5 KWHs due to clouds. So if I shift 10 KWHs per day to cover the high time of use, and the other 12 is used at the cheap rate, that 8,000 KWHs is saving me a total of 8,000 KWH x $0.295 = $2,360 per year. Even adding in the cost of the battery, hybrid inverter, and the install, it can certainly pay off at these new higher electric rates.

Assuming Schneider does fix their software, you ae looking at a $5,000 inverter with Insight Home and a Watt-Node, and then add 6 x $1,600 for LFP server rack batteries. That is $14,600 if you install it yourself. Not sure what an electrician would charge. So my system would have cost about $27,000 give or take a bit. Oh wait.... Take off the 30% tax credit on the batteries. Or let's not, that could cover the install cost. $27,000 / $2,360 per year = 11.44 years. Not ideal, but you still get a few free energy years.

Under NEM 3.0 the on peak rate may go up, but the off peak looks about the same. I only buy off peak power, and even that is rare except on crazy summer heat (4 to 6 weeks a year) and the bad overcast where we get little sun (another 4 to 6 weeks).But my 8 megawatts is every year over 3 years including bad production days. My system total now has exceeded 27 megawatt hours. With a battery, the amount they credit us really does not matter, we don't want to export any power. Use it all on site. In the summer, I was actually able to time shift over 15 KWHs on many days because the central A/C was using so much I was able to run the battery down during the peak rate and cycle it back up during the cheap time near noon. But in the winter I can't do that, so what I wrote above is an average for the whole year. But the idea still holds. Try to put as much energy into the battery as you can, and then run off it while not buying ANY grid power. When I am using a ton of power for A/C, The stored battery was still able to run the whole 4 pm to 9 pm on peak rate time. So the little power I did buy was off peak or super off peak. If I start needing more power in a day, I will try to only buy off peak and use battery stored energy if needed during the peak rate. As much as my A/C draws, the XW-Pro inverter had no trouble keeping my power meter at zero all through the on peak time. The grid did supply the start surge, and then it takes my PLC setup about 10 to 15 seconds to adjust the export current to make the batteries cover the full run power. When the compressor cycles off, I do end up exporting a small bit as it takes the PLC 10 to 15 seconds again to ramp the export power back down to zero the grid power yet again. I may want to tighten up the reaction time a bit if they start looking closer at the total import and export, but for now, they only take a net total for an entire hour. Those 10 second import/export bumps do not show on the bill. And even if they did, we are talking about 3,000 watts for about 10 seconds. That is a pulse of about 0.00833 kilowatt hours each time the compressor starts. Then I export that when the compressor stops.

 

[Hedges]

Even at today's credit of 25 cents, having to buy it back at 45 cents is a big rip off.

I look at it as a bargain for energy storage, not a rip-off.

I put GT PV hardware cost at $1/W, $0.025/kWh
Batteries, best price $0.05/kWh of cycle life (not including inverter.)

I can buy 2x the GT PV, export 2 kWh at $0.25 each, import 1 kWh at $0.45, so my kWh consumed on-peak cost me $0.05

If I buy a battery, $0.025 to make the kWh + $0.05 to store the kWh = $0.075/kWh
For a time, it looked like my on-peak rate would be 3x off-peak, so just over-producing 3x cost me no more than battery.

So I think excess export is the way to go under NEM 1.0 & 2.0, while for 3.0 you need a battery.

I store up over 10 KWHs a day on average. That 20 cents different x 10 = $2 a day saved by the battery. That comes out to over $700 a year.

So if I shift 10 KWHs per day to cover the high time of use, and the other 12 is used at the cheap rate, that 8,000 KWHs is saving me a total of 8,000 KWH x $0.295 = $2,360 per year.

Assuming Schneider does fix their software, you ae looking at a $5,000 inverter with Insight Home and a Watt-Node, and then add 6 x $1,600 for LFP server rack batteries. That is $14,600 if you install it yourself.

So my system would have cost about $27,000 give or take a bit. Oh wait.... Take off the 30% tax credit on the batteries. Or let's not, that could cover the install cost. $27,000 / $2,360 per year = 11.44 years.

$14k cost, $700/year savings, 5% or 20 year to break even, and by then batteries are worn out. Bad investment.

$27k cost, $2400/year savings for 9% or 11 years, although that is not an investment return to compare with financials because you can't sell to get back cash investment. Need to analyze to end of life, and now that interest rates have returned to normal consider discounted cash flow.

1/3 of system is PV, longer life. 2/3 is battery (and inverters may or may not be shared between the two parts.)
I think PV panels, if they don't have a bad degradation mechanism, can be 25 to 40 years.
Inverters can be 20 years.
Batteries 10 to 16 years of deep cycling.
Maybe with one battery replacement, system use over 20 years will show how much return.

Rising utility rates could tip it in your favor. I think rates remained relatively low for many years since I started in 2003/4, but shot up recently.

 

[400bird]

$14k cost, $700/year savings, 5% or 20 year to break even, and by then batteries are worn out. Bad investment.

Just lines above he broke out the battery vs inverter and bos, with the battery as

and then add 6 x $1,600 for LFP server rack batteries.

So, if you want to throw out the inverter and bos with the battery in 10 years, go ahead. But the
inventer has an expected life span in the decades, so should outlast 2 sets of batteries.


I can't figure out how to calculate payback past the first set of batteries. The predictions for battery price 10 years out are all of the place and all look like guesses.

 

[GXMnow]

I can't figure out how to calculate payback past the first set of batteries. The predictions for battery price 10 years out are all of the place and all look like guesses.

Same here. My hope on the Bolt cells is to get 7+ years. At that point they have easily paid for themselves at the cost we got them for. But in 5 more years from now, what is the battery market going to be? I am looking at Zinc Bromide batteries. That may be the future for home storage.

 

[fafrd]

Just lines above he broke out the battery vs inverter and bos, with the battery as

So, if you want to throw out the inverter and bos with the battery in 10 years, go ahead. But the
inventer has an expected life span in the decades, so should outlast 2 sets of batteries.


I can't figure out how to calculate payback past the first set of batteries. The predictions for battery price 10 years out are all of the place and all look like guesses.

I think you can look at incremental costs per kWh of battery in an modern EV to get a bead on where battery costs per kWh are heading over the next 5-10 years…

And cycle-life of LiFePI4 is now 6000 cycles or over 16 years at 100% per day (meaning probably more than 20 years @ 80% per day).

ESS is a tiny, tiny industry today compared to what it is going to be 10 years from now. We can’t help but think small because it is all we know…

My gut tells me that solar + ESS systems of the future will share a 50/50 split on costs (and we know the trend of the solar part of that equation).

Squeezing into NEM 2.0 before the deadline will be a better-than-average deal and being an early adopter of NEM 3.0 will be a rawer-than-average deal, but that’s the case for most any transition.

I know, since I was lucky enough to squeeze into NEM 1.0 just before the transition to NEM 2.0 (so no NBC’s for me…).

If NEM 3,0 went to monthly net billing the way the utilities lobbied for, it truly would have killed rooftop solar (because no summertime overproduction could be used to offset wintertime consumption).

The fact that the Final Decision maintained Annual TrueUp, along with the stipulation for arrays sized to produce up to 150% of annual consumption, means the eco omits of rooftop solar continue to pencil out (with a Home Battery Sized to offset overnight consumption and assuming continued progress on the cost and capability of ESS over the next 5 years).

 

[mickri]

New to residential solar but lived 9 years off the grid on my sailboat. That was a low voltage 12 volt system.

After much delay I am plan to install solar at my home outside of Paso Robles CA as soon as I get the permits. No battery backup. Been reading through this entire thread. Have talked with PG&E. I saw lots of discussion early on about a monthly charge based on the size of the array. Did that go by the wayside in the final NEM 3.

There is no mention of that in the bill explanations on PG&E's website. Only that the excess exported over imported will be credited at .05 per kwh at the annual true up Also didn't see that in the recent articles I read about NEM 3. If there is a monthly charge based on array size that would destroy any value to my proposed solar system and I won't do the installation.

 

[Ampster]

I saw lots of discussion early on about a monthly charge based on the size of the array. Did that go by the wayside in the final NEM 3.

Yes that was eliminated in the final proposal. From what I understand you need to have an NEM application into PG&E by mid April. Some members have interpreted this to mean that the install does not have to be completed by that date.

 

[fafrd]

New to residential solar but lived 9 years off the grid on my sailboat. That was a low voltage 12 volt system.

After much delay I am plan to install solar at my home outside of Paso Robles CA as soon as I get the permits. No battery backup. Been reading through this entire thread. Have talked with PG&E. I saw lots of discussion early on about a monthly charge based on the size of the array. Did that go by the wayside in the final NEM 3.

There is no mention of that in the bill explanations on PG&E's website. Only that the excess exported over imported will be credited at .05 per kwh at the annual true up Also didn't see that in the recent articles I read about NEM 3. If there is a monthly charge based on array size that would destroy any value to my proposed solar system and I won't do the installation.

The monthly charge based on array size or ‘solar tax’ as it’s often called, is gone.

If you don’t plan to install a battery, you actually want to get your system signed up under NEM 2.0 before the transition to NEM 3.0 in April (you still have 1-2 years to complete the build and get Permission to Operate, but you need to register before the deadline in April or you’ll be forced onto NEM 3.0.

NEM 2.0 is straightforward - any positive NEM balance at Annual True Up get’s converted to Net Overgeneration (annual kWh exported - annual kWh imported) x Net Surplus Compensation Rate of a few cents per kWh.

Under NEM3.0, the concept is similar except that export will not be credited a full retail rate but an Avoided Cost rate that is different during each hour of the day and is actually less than the Net Surplus Compensation Rate through the peak-solar-production hours surrounding midday:




So under NEM 3.0, you’ve got to at least have a battery big enough to offset overnight consumption for the system to make any sense. Rather than exporting excess solar power at midday for ~13% of the off-peak retail rates you’ll pay overnight, store that is excess solar energy into your battery and use it to avoid any import from the grid overnight.

 

[mickri]

Thanks for the clarification about the solar tax. According to the lady I talked to at PG&E I need to have the system installed before submitting the connection application.