Does a battery ever have a positive ROI with net metering

[mswlogo]

Can someone critique my back of the napkin ROI on adding a Battery to my Solar system.

I have a 15Kw Enphase system (new)

I live in NH with Eversource at $0.24 / KWh
200 Amp service.

Eversource offers 75% NetMetering (I think, I get mixed info on how it’s calculated). No off peak rates.

Most batteries are around 92% efficient (round trip).

You can think of NetMetering (for me) as 75% efficient (round trip).

Roughly 1 battery for $10K with a capacity 10Kwh.

NetMetering is unlimited Batteries for $0K with unlimited capacity and for unlimited storage time and 0 loss.

The battery is 17% more efficient than NetMetering. With a cap of 10Kwh a day.

So let’s guesstimate that 6 month of the year I over produce.

That’s 10Kwh * 30 days a month * 6 months
1800 KWh. But we are only saving 17% so I’d save 306 kWh (by storing in the battery vs the grid). That’s being optimistic.

Now multiply that by electric utility rate. 306 * 0.24 kWh = $73/yr savings.

$10,000 / $72 = 136 years to break even

I use about 30 KWh a day. Probably could cut that back to 10 kWh during a power failure. House is all electric (geo thermal heat). So 1 day of backup. It would cost a fair bit more to allow for true off the grid mode during power failure and I have a manually switched generator.

 

[Frontrange PV]

Interesting approach. I’ll let others comment on the specifics and just summarize this way: I think getting to a positive ROI with a battery is pretty near impossible with current prices.

I think it’s more useful to consider the value to be found in its backup function. You already have a solution for that, but one with some caveats such as inconvenience, maintenance, fuel expense and whatnot.

Our solution FWIW is to go light on a backup battery and consider future options for longer term backup should that become desirable. We have just 1 Powerwall2, which can carry our house unassisted for 16-20 hours. We don’t have an alternative power source other than solar at present.

Only you can decide if your present setup would warrant the cost of a battery. Good luck with your decision!

 

[dhrivnak]

Can someone critique my back of the napkin ROI on adding a Battery to my Solar system.

I have a 15Kw Enphase system (new)

I live in NH with Eversource at $0.24 / KWh
200 Amp service.

Eversource offers 75% NetMetering (I think, I get mixed info on how it’s calculated). No off peak rates.

Most batteries are around 92% efficient (round trip).

You can think of NetMetering (for me) as 75% efficient (round trip).

Roughly 1 battery for $10K with a capacity 10Kwh.

NetMetering is unlimited Batteries for $0K with unlimited capacity and for unlimited storage time and 0 loss.

The battery is 17% more efficient than NetMetering. With a cap of 10Kwh a day.

So let’s guesstimate that 6 month of the year I over produce.

That’s 10Kwh * 30 days a month * 6 months
1800 KWh. But we are only saving 17% so I’d save 306 kWh (by storing in the battery vs the grid). That’s being optimistic.

Now multiply that by electric utility rate. 306 * 0.24 kWh = $73/yr savings.

$10,000 / $72 = 136 years to break even

I use about 30 KWh a day. Probably could cut that back to 10 kWh during a power failure. House is all electric (geo thermal heat). So 1 day of backup. It would cost a fair bit more to allow for true off the grid mode during power failure and I have a manually switched generator.

True with net metering there is little to no ROI with batteries. And typically the round trip efficiency is worse than the stated efficiency. Often as low as 80%. If you want or need backup or can arbitrage time of use that helps. But ROI no with net metering.

 

[adspguy]

If you can enroll your battery in one of the VPP programs, you get a much better ROI even with net metering at a high payback, mine is 1:1. In my case in Mass with Eversource I get over $2500/yr back for my 3 powerwalls on the Connected Solutions program. Also under the SMART (srec replacement in Mass) there is a battery incentive that adds 3 cents /kWh generated kicker. Having the batteries for backup is priceless when the grid goes down for a day like it did recently for me. When I priced my system with and without powerwalls, the solar only looked like it would pay for itself in about 6 years, whereas the Solar+powerwalls was only 4.5 years due to the higher solar gen and VPP paybacks. I have 1:1 net metering and only discharge the powerwalls during outages or for Connected Solutions events which they control.

YMMV greatly in your state, and utility etc.

 

[zƬesla]

Eversource in NH no longer supports Tesla for VPP. Currently only Enphase IQ. This seems to change every 1-2 years.

Net metering for NH: "Each kilowatt hour of Net Sales will earn a monetary bill credit equal to the sum of the Default Energy Service charge, the Transmission Charge, plus 25 percent of the Distribution Charge." Very much wish we had 1:1.

Bottom line, unlikely to see ROI, but the PWs have come in handy during outages and I prefer them to a generator.

 

[TacoGuy]

Can someone critique my back of the napkin ROI on adding a Battery to my Solar system.

I have a 15Kw Enphase system (new)

I live in NH with Eversource at $0.24 / KWh
200 Amp service.

Eversource offers 75% NetMetering (I think, I get mixed info on how it’s calculated). No off peak rates.

Most batteries are around 92% efficient (round trip).

You can think of NetMetering (for me) as 75% efficient (round trip).

Roughly 1 battery for $10K with a capacity 10Kwh.

NetMetering is unlimited Batteries for $0K with unlimited capacity and for unlimited storage time and 0 loss.

The battery is 17% more efficient than NetMetering. With a cap of 10Kwh a day.

So let’s guesstimate that 6 month of the year I over produce.

That’s 10Kwh * 30 days a month * 6 months
1800 KWh. But we are only saving 17% so I’d save 306 kWh (by storing in the battery vs the grid). That’s being optimistic.

Now multiply that by electric utility rate. 306 * 0.24 kWh = $73/yr savings.

$10,000 / $72 = 136 years to break even

I use about 30 KWh a day. Probably could cut that back to 10 kWh during a power failure. House is all electric (geo thermal heat). So 1 day of backup. It would cost a fair bit more to allow for true off the grid mode during power failure and I have a manually switched generator.

I've looked at it time and time again. My energy supplier has multiple rate plans and uses a demand rate to cut off-peak hours to the minimum on certain plans. Even with the $100-$120 per month in demand surcharge savings doing peak shaving and a reduced off peak rate. The break even point for a 3 PW install here would be > 10 years. Battery life span is only 10 years and there will be storage Deg. in addition to 20/80 rules for charging and discharging.

If you have frequent power outages or you are rural and want peace of mind, than it has further benefits, otherwise the grid and your NetMetering buy back is way better a battery than the one you put in your house will ever be.

 

[jjrandorin]

Battery life span is only 10 years

A lot of people say this, but I am not sure where it comes from. The warranty for the battery is "70% capacity at 10 years", so that does not mean the life span of the product is 10 years.

To answer the thread question though, in general, if you dont have any value on the backup portion for some reason (you dont care, you already have a generator, etc), and put no personal value on being more self reliant, then no, it doesnt generally pencil out unless you are someplace where there is a huge delta between time of use charges or something like that.

 

[GregBallantyne]

I just put together another take on ROI....batteries included. It makes me offer a critique - you did not apply an inflationary rate to your grid power rate. It won't be the same 10 years from now.
My goals didn't put ROI at the top of the priority list, but I was looking at it recently anyway. Since I got Solar Roof w/3PW, my system was toward the more expensive side of things. But, when I added the contract price for Solar Roof & 3 PW ($95k after tax credits), and Model 3 ($50k after tax credits) and then used the saved costs of the annual electricity generated and the gasoline not bought, and applied a very reasonable inflation rate, I move into positive ROI territory during the 18th year. I think I actually have a fighting chance to see that day come. The big part of that is that the avoided gasoline costs are covered by the power generated - you've got to throw them in, since your solar system is covering that avoided cost. At least it is for me, charging my car on excess solar.

 

[Jeremy3292]

Very simply put if your utility forces you onto a TOU plan (which is becoming more and more prevalent), then batteries can certainly have an ROI. But if there is no requirement to be on a TOU plan and you just have a standard per kWh price, than they do not have a calculable ROI. There is some math that could be done in regards to voluntarily switching to a TOU plan and using batteries during peak use and thus then paying a lower per kWh price than standard rates, but I imagine that ROI would make no economical sense.

You also have to segregate solar costs from battery costs in IMO to get a true ROI on just the batteries. That would look something like calculate monthly cost of electricity with just solar panels, calculate monthly cost of electricity with solar and batteries (e.g. can avoid peak rates with batteries), the delta between those two costs would be your savings, apply those monthly savings against the cost of the batteries. ROI is then calculated but probably something astronomical and not viable from a strictly economics/math perspective.

Peace of mind, outages, etc is not calculable and is subjective in the eyes of the beholder.

 

[h2ofun]

IMO, and I have 7 batteries, I tell folks batteries have NO ROI. If you have money to burn, go for it, but they are not zero issues.

 

[TacoGuy]

A lot of people say this, but I am not sure where it comes from. The warranty for the battery is "70% capacity at 10 years", so that does not mean the life span of the product is 10 years.

To answer the thread question though, in general, if you dont have any value on the backup portion for some reason (you dont care, you already have a generator, etc), and put no personal value on being more self reliant, then no, it doesnt generally pencil out unless you are someplace where there is a huge delta between time of use charges or something like that.

Mesure of the number of viable charge/discharge cycles is right around 3600. After that it may be a target of 70% capacity, but you can't count on it - and warranty is over. Even at that usable is diminished to even less stored charge, battery cannot be fully discharged without potential damage.

I don't think it's a wise investment if you have Net metering, Grid is in effect your battery.

 

[cali8484]

Did you get a quote for Enphase battery? It would be interesting to see what financial ROI Enphase thinks you would get with a battery.

 

[brkaus]

Austin Energy has a value of solar plan where all electricity generated by ones solar panels are paid a fixed price ($0.09). No matter if it is consumed locally our sent out on the grid. Heck, even on battery with the grid out, you are getting paid for the solar you use.

No benefit to batteries here except as a backup. Which of course does have some value.

 

[nwdiver]

Our electrician lives in an area where he gets 0 credit for his exports so batteries have value. But the first step was to dramatically oversize his system since solar is hilariously cheap now. That's the first paradigm shift I needed to accept. MASSIVE curtailment. He needed to overproduce not just a little. But A LOT. ~2x what he used. This was the only way to ensure the batteries were utilized fully nearly everyday. Cheap solar is what made this possible. If there was only sufficient surplus half the time the batteries would effectively be 2x the cost. You need to be giving away or losing ~half your production regularly before storage makes sense.

The cost of storage for DC coupled batteries is also a lot lower now but you need to shop around. RUIXU is offering 16kWh 48v packs for ~$3k.

 

[TacoGuy]

Austin Energy has a value of solar plan where all electricity generated by ones solar panels are paid a fixed price ($0.09). No matter if it is consumed locally our sent out on the grid. Heck, even on battery with the grid out, you are getting paid for the solar you use.

No benefit to batteries here except as a backup. Which of course does have some value.

Check your bill! You have to be paying a grid tie fee based on size of solar system, and also may be charged for each KW of energy used at 9cents. Hence the credit for all energy produced. You are only getting credit for net energy put on the grid, and your solar consumed is taxed but there is a 9cent credit. There may be a peak consumption surcharge as well.

 

[Vines]

Our electrician lives in an area where he gets 0 credit for his exports so batteries have value. But the first step was to dramatically oversize his system since solar is hilariously cheap now. That's the first paradigm shift I needed to accept. MASSIVE curtailment. He needed to overproduce not just a little. But A LOT. ~2x what he used. This was the only way to ensure the batteries were utilized fully nearly everyday. Cheap solar is what made this possible. If there was only sufficient surplus half the time the batteries would effectively be 2x the cost. You need to be giving away or losing ~half your production regularly before storage makes sense.

The cost of storage for DC coupled batteries is also a lot lower now but you need to shop around. RUIXU is offering 16kWh 48v packs for ~$3k.

I took a look at the RUIXU site as this price seemed pretty crazy low. Unfortunately, this battery is not code compliant with residential installations on buildings in most jurisdictions. UL 9540 listing is required by both NFPA 855, IRC and the IFC. I see they are UL 9540 pending, but I am very interested to know what edition they are testing to, and whether they performed the required 9540A testing of the latest edition, in order to install near, on or in buildings. It might be that they are only allowed by code to be installed on the ground outdoors away from exposures.

There is some danger in my eyes as more people decide to DIY an ESS, and choose equipment that isn't properly certified. There is a reason why the offerings from the larger manufacturers cost more. They have done the fire safety and other testing required to ensure the battery doesn't light itself on fire if one of the electrical components fails, or if the installation has quality issues.

As to the OP question, I don't think an ROI is really in the cards unless you are under certain circumstances. For instance SGIP paid a significant portion of my installation and therefore I can see a less than 10 year payback, and shorter if PG&E keeps jacking the rates up so quickly. In 10 years, the VPP payouts alone will be near half my system cost after incentives.

 

[nwdiver]

I took a look at the RUIXU site as this price seemed pretty crazy low. Unfortunately, this battery is not code compliant with residential installations on buildings in most jurisdictions. UL 9540 listing is required by both NFPA 855, IRC and the IFC. I see they are UL 9540 pending, but I am very interested to know what edition they are testing to, and whether they performed the required 9540A testing of the latest edition, in order to install near, on or in buildings. It might be that they are only allowed by code to be installed on the ground outdoors away from exposures.

Signature Solar is offering a unit that is suspiciously similar that has UL9540A certification for ~$3400. LiFe is <$100/kWh at the cell level so we should be seeing a lot more packs at the ~$200/kWh price point.

But over-production needs to be the first step. Mounting solar vertically to increase winter, morning and evening generation is likely going to make more sense that storing surplus at noon.

 

[Vines]

Signature Solar is offering a unit that is suspiciously similar that has UL9540A certification for ~$3400. LiFe is <$100/kWh at the cell level so we should be seeing a lot more packs at the ~$200/kWh price point.

Buyer beware is my response.
That Voc appears to be edited through Adobe PDF editor. See the name of the product.
For instance see the list of accredited test labs that can certify a product to 9540. Intertek does not have OSHA accreditation for UL 9540 as a test lab.
https://www.osha.gov/nationally-recognized-testing-laboratory-program/its
No more off topic from me on this thread.

I agree that with the current prices of PV, the first step of financial benefit is to cover every surface with modules.

 

[brkaus]

Check your bill! You have to be paying a grid tie fee based on size of solar system, and also may be charged for each KW of energy used at 9cents. Hence the credit for all energy produced. You are only getting credit for net energy put on the grid, and your solar consumed is taxed but there is a 9cent credit. There may be a peak consumption surcharge as well.

I don't have solar (yet), but friends do. There is no grid fee based on the size of the system.

Austin Energy Value of Solar is pretty straightforward (for better or worse) -
- Pay a monthly fee, same if one has solar or does not have solar (around $15)
- Pay for electricity plus energy fees. 5 tiers roughly ranging from $0.07 to $0.14 (depending on season, etc)
(They just raised this but I don't know exact numbers, about 8%)
- Get paid for solar energy generated at $0.09.

Solar energy does not change other fees nor does it count towards your own use so it does not lower your tier pricing per kWh used.

The setup requires two meters. One on the main and one on the solar generation circuit.

 

[TacoGuy]

I don't have solar (yet), but friends do. There is no grid fee based on the size of the system.

Austin Energy Value of Solar is pretty straightforward (for better or worse) -
- Pay a monthly fee, same if one has solar or does not have solar (around $15)
- Pay for electricity plus energy fees. 5 tiers roughly ranging from $0.07 to $0.14 (depending on season, etc)
(They just raised this but I don't know exact numbers, about 8%)
- Get paid for solar energy generated at $0.09.

Solar energy does not change other fees nor does it count towards your own use so it does not lower your tier pricing per kWh used.

The setup requires two meters. One on the main and one on the solar generation circuit.

I searched for the plans and read through the solar addendums to the plan.

You get straight credits for all solar generated, and charged for all consumption based on plan. Essentially, you are paying all tariffs and taxes on all electricity used and then credited the solar production against the bill. In other net metering states/areas you don't pay tax for what you use while the solar is generating.

No one way is better or worse than the other. Each has its upside and downside.