Whole house battery backup system?

[HFWR]

I have enough portable Ecoflow units to power the fridge for a couple of days, and maybe the furnace for a few hours, but running the ac would require about 3.5kw everytime it kicked on. Time for Holiday Inn Express!

 

[Mansderm]

I'm looking for input/opinions:

Our electric co-op has a new pilot program offering to lease co-op members without solar panels (that's us) a whole house battery backup system. The offer is for a 10 year lease (early termination fee of up to $500) with no up front installation charge. I can lease one or two 25 kWh batteries at a cost of $37/mo per battery, including tax. The co-op owns and manages the batteries, handling all maintenance and warranty-related work.

Here's the catch: The batteries will be used to help support the grid when needed but will always reserve a minimum of 50% of the battery capacity for our use if we lose power. The co-op will also provide us with a monthly bill credit (currently set at a flat $40) to pay for the electricity to charge/recharge the batteries.

We live in a rural area in an all-electric home, no gas. When the power goes out we lose all services, even water. We experience two or three outages every year, generally lasting only a few hours, but have had longer outages. I have a portable generator which we have used to run a window a/c unit or portable heater if the outage was in the peak of the summer or winter. That involves running extension cords and always making sure I have fresh fuel for the generator, which is a bit of a pain. That's why this offer has caught my interest.

Some brief research says the cost to purchase an installed whole house battery system of that size would be $25,000 or more, something that doesn't come anywhere close to passing my cost/benefit threshold. But leasing a two battery system for $74/mo is tempting.

The co-op says they will lease only 20 batteries in this pilot program and I got my application in early so I'm on the list. I got a call Friday saying all the info and the photos I sent with my initial interest form look good, all that is remaining is for them to come out and get an in-person look next week, then sign the lease agreement.

Thoughts?

I approach anything that requires a contract that is more than 1-2 pages long which includes signatures as a No Go. 5+ page contracts are not written for the consumer. They are written for the vendor including all legal rights. Basically they are wanting to set up power banks and not have to buy or rent more land or space. They should be paying you to lease your property. The odds of you coming out ahead are low. There is obviously something in it for them since they initiated the program and their lawyers wrote the contract.

 

[RetMD21]

We had a 20 Kw backup system installed at our house about 7-8 years ago; it was the largest we could buy at that point in time. We have a large house and a number of outdoor sources of power draw as well, so we couldn't put everything on the system; not a huge downside. The cost was nowhere near what you were quoted, and ours had the additional expense of wanting it tied into our natural gas line with that run coming from the opposite side of the house through the crawlspace.

My concern with only having 50% capability available would be that electrical codes would probably dictate (much like in our situation) many sources of draw would have to be left off the system, since most codes authorities look at things like maximum draw, and in your case 50% of 25Kw would only be 12.5 Kw. That could be why you are looking at a two battery system.

Personally I would bite the bullet and buy your own system. Too involved for me the scenario you posted, and my wife also doesn't like sharing, being an only child

He's thinking of moving. Does buying make sense?

 

[Koolau]

I approach anything that requires a contract that is more than 1-2 pages long which includes signatures as a No Go. 5+ page contracts are not written for the consumer. They are written for the vendor including all legal rights. Basically they are wanting to set up power banks and not have to buy or rent more land or space. They should be paying you to lease your property. The odds of you coming out ahead are low. There is obviously something in it for them since they initiated the program and their lawyers wrote the contract.

If it is a win-win, then I don't see the problem. Having said that, the devil may be in the details.

 

[REWahoo]

He's thinking of moving. Does buying make sense?

As I stated in post#18, we don't know how much longer we will live here, so forking over $10K to $20K for a whole house generator doesn't make much sense to me. That's especially true when compared to the low monthly cost of a no-maintenance lease that I can terminate at will for $450.

 

[plank2505]

There is some not-so-great advice in this thread. It makes no sense to net the $40 credit against the battery lease payment. The credit is intended to mitigate the liability the lessee is taking on by signing up to be a mini power plant.

On its face, this deal seems absolutely ridiculous. It would make more sense for you to have an inflow/outflow meter and for them to credit outflow against inflow since that inflow was for storage before being used by other homes and wasn’t your usage. I have no idea why they don’t just do this, unless they are trying to avoid needing to upgrade your meter, or they know that you’re going to pay well over $40/mo for this storage mechanism and they’re just looking for another revenue stream.

It’s going to come down to the terms of the agreement, which you don’t have so you can’t share it with us. So all of our advice is not very useful until you can share the terms.

Without some favorable terms in there for you, you are signing up for an UNLIMITED liability where you are paying for “usage” as energy is being temporarily stored in your batteries, just to go out again to power other homes (which the company presumably gets to charge a second time for the same kWh).

 

[REWahoo]

There is some not-so-great advice in this thread.

I agree, especially from the posters who apparently haven't read the entire thread and have failed to gain an understanding of how this pilot program works and what my needs are.

 

[REWahoo]

Battery system installation complete. Here are some before, during and after photos.

The install did not go smoothly. What was supposed to take one day ended up taking three. The crew of three electricians that showed up on day one spent most of the day drilling and jackhammering through some serious rock to set the posts for the equipment rack and to dig a trench from the power pole to the rack. Two of them returned the second day and assembled the rack and battery packs, then discovered an issue with my 200W main breaker panel which they decided needed to be replaced. One electrician returned on day three, and spent six hours replacing my panel & breakers (no cost to me), wiring in the batteries, and performing a series of tests. Part of his testing was switching our house to battery power then back to the grid, which was almost undetectable.

I now have two 25kW battery packs, two 11.4kW inverters and a new main breaker panel. I eagerly anticipate our next outage to see how it performs. I'll also be closely monitoring our monthly bill to see if the co-op reimbursement fully covers the added cost of power they sell back to the grid.

 

[Koolau]

Wow, that was not a small project. Thanks for sharing the pics and narrative. Best of luck as you use the system. Looking forward to updates.

 

[Golden Mean]

Battery system installation complete. Here are some before, during and after photos.

Very cool!

Two of them returned the second day and assembled the rack and battery packs, then discovered an issue with my 200W main breaker panel which they decided needed to be replaced.

Did they give you details on what the issue was with your breaker panel? Was it related to the battery install or just defective in general?

ETA - I was envisioning the batteries going into your basement, but since not everyone has a basement and those batteries are huge, I guess it make sense they are outside.

 

[skyking1]

Growatt are good inverters. On the market they are higher end units.
Each 11.4KW unit can produce 47.5 amps continuous, for 95 amps total.
This is double my system for the inverters and triple for the batteries, if I opt for a single 16. I may get two and cut to the chase so to speak.

 

[REWahoo]

Did they give you details on what the issue was with your breaker panel? Was it related to the battery install or just defective in general?

The electrician that put the panel in when we built the house in '98 apparently over tightened and/or cross-threaded the lug on the neutral bus bar. Although it never caused us any problem they were unwilling to trust it with this new set-up and replaced the panel at no cost to me.

...those batteries are huge...

The installers called them "power modules" comprised of five batteries, a controller, and the inverter hanging on the end. Each module weights about 600 lbs.

 

[skyking1]

Did they give you details on what the issue was with your breaker panel? Was it related to the battery install or just defective in general?

Looking at the pictures, which are great and very informative, the panel in question is the first disconnecting panel situated below the meter, not the panel in the house itself.
The internal bus bar on old panels and standard panels is rated@ 200 Amps.
NEC requires that the bus can handle all the breakers clipped onto it, and the end feed. NEC allows for a 120% uprate for this purpose.
200x 120% = 240 amps
The input breakers from the pair of inverters are at least 50 Each.
So now you have a situation where much more than the bus bar rating could theoretically land on the bus and result in overheating and a fire.
There are a couple of ways to address this. you can derate the feed breaker in from the power company, say a 180 or something.
Or you can put a bus bar in that is rated for more amps. That is what I am doing. I have a 225 bar x 1.20 =270 amps.

EDIT: thanks Wahoo we cross-posted.

 

[REWahoo]

Follow up:

It has been one month since the installation of my battery back up system and I just received my first monthly bill. My usage for the month was about 10% higher than for the same period in 2023 and 2024. That was due to slightly warmer temperatures during the month and to charging the two 25Kw batteries to 100% (they were at 40% when installed).

My contact at the co-op (talked with her a few days ago) said they had not sold any power to the grid from my batteries which I believe to be correct. They can only make money by selling to the grid when it is under stress and the wholesale price goes up significantly, which will happen once temps hit triple digits. FWIW, our forecast high for Wednesday is 103 !

The bill did have one big surprise. I was told to expect a $40 monthly credit during the first year of the pilot program but my credit amount was double that. Not sure why, but since the monthly lease cost is $74, that $80 credit is very nice. Hope it wasn't a mistake...

 

[Texas Proud]

Maybe $40 per battery pack... so $80 per month...

 

[Koolau]

I hope it w*rks out well for you Wahoo. Please keep us posted.

 

[REWahoo]

Another update:

No issues with the system to date but we've not had a power outage so no real test.

The co-op did partially discharge my batteries to the grid one time, I assume as a test. Late one afternoon they sent 20kW (out of 50) to the grid, then recharged the batteries back to 100% late that night when my rates are at their lowest ($0.081 kWh). So the cost to me for the recharge was about $1.60. I was unaware of any of this until the following day when I checked my usage via the co-op website.

I was a bit surprised to be contacted late last week by a local HVAC company who said they have been contracted by the co-op to install a soft start kit on our heat pump at no charge to us. One of our neighbors who is also in the pilot program also got a call from them. I am going to contact the company that installed our HVAC system to see if there is any benefit to having a soft start installed as we have a two-stage system and my internet sleuthing indicates questionable value for anything other than single stage compressors. I also want to be sure it will not void my warranty.

On we go...

 

[Golden Mean]

Yeah, the "hard start kit" (or "soft" in your case) is a total scam and not needed, afaik. If I remember right, it's a cap that they charge $200 for, when you can buy AC compressor caps all day long for $20.

 

[Koolau]

Yeah, the "hard start kit" (or "soft" in your case) is a total scam and not needed, afaik. If I remember right, it's a cap that they charge $200 for, when you can buy AC compressor caps all day long for $20.

Wow. This is all new to me. Never heard of the hard or soft start "kits" - but there are books full of stuff I know nothing about, so...

 

[ncbill]

Yeah, the "hard start kit" (or "soft" in your case) is a total scam and not needed, afaik. If I remember right, it's a cap that they charge $200 for, when you can buy AC compressor caps all day long for $20.

Soft start is electronic & IMHO worth it for single-stage compressors to cut the starting amperage draw.

A hard start kit is just an extra capacitor which I wouldn't bother with either.

And am I jealous of the OP, as I've spent thousands recently for various 'solar generators' plus portable panels.

 

[REWahoo]

Turns out installing a soft start kit on my Carrier two stage heat pump would void the warranty (2 yrs labor, 10 yrs parts). I cancelled the installation and informed my co-op. I am interested to hear what they have to say, if anything.

 

[braumeister]

Smart.

 

[REWahoo]

The story continues...

After informing my co-op that my AC installer, a Carrier dealer, had said installing a soft-start kit would void my warranty, they contacted the battery system supplier, Base Power. According to my co-op, Base Power said they had never run into this issue even though they had installed thousands of systems. They wanted the name of my AC company which I provided, and said they would contact them about the issue.

Meanwhile I contacted Carrier's customer service dept via email and asked if installing a soft-start kit would void my warranty (trust but verify...). Their email response: "Installing a soft start kit will not void your warranty, provided that the installation is performed by a licensed Carrier dealer."

I sent the Carrier email response to my co-op who said Base Power had been unsuccessful in getting my AC company to agree to install a soft-start kit. They contacted two other local licensed Carrier dealers with the same result. A classic Catch 22. Not sure why none of the local Carrier dealers won't do it, but I'm not going to push it.

Bottom line, my back up system may not have enough amperage to start the compressor on our central AC system. After three unsuccessful auto attempts the battery system will go into standby mode. Once I reduce the electrical load by I turning off the central AC I can do a manual start of the back up system using the newly-supplied phone app which allows me to monitor my home electrical load and status of the batteries.

Although having a seamless switchover of all our electrical systems including the central AC would be preferable, I am OK with the system even without that capability. That's because whenever we have a summer outage we will not use the central AC but will rely on a smaller AC system in the playroom we had built for the grandkids when they were small. Even if the back up system powered the central AC, we would not use it preferring to use the AC in the playroom to prolong battery life.

Hopefully there will be an extended delay prior to my next update, describing how the system performed during an actual outage.

 

[Texas Proud]

Any update? Just curious to pass along to some people...

 

[REWahoo]

Any update? Just curious to pass along to some people...

After three full months of use, so far, so good.

No power outages to my knowledge, so nothing to report about performance in that situation.

Most days the battery system is called on three times to feed power to the grid - around 6am, around noon, and again between 4 and 10pm. The batteries are discharged down to 20% - 50% of capacity, then recharged back to 100% within the next two to three hours. This wasn't the summer use schedule I expected, thinking the batteries would be asked to feed the grid once daily in the late afternoon then recharged overnight when demand was lowest. However, the more frequent discharge/charge cycles are not a problem as I am not aware when this happens unless I look at the battery app - there is no other indication.

When the batteries are used to feed the grid they also feed power to the house. The concern that the batteries would not supply sufficient amperage to start our central AC compressor proved to be a non-issue, so no soft-start kit is needed.

I have been closely monitoring my monthly cost to recharge the batteries for the power fed to the grid vs. amt the co-op reimburses me. The co-op reimbursement has always exceeded my cost by a few dollars, so I have no complaints there. The co-op has made it clear on multiple occasions that this is a test program and the amt of reimbursement may change but that their goal is to insure battery system users are fully reimbursed for grid support expenses.

It will be interesting to see how battery use changes as temperatures decline in the fall, and what the discharge/charge timing is this winter.