Whole house battery backup questions.

[Jerry1]

I didn’t read all the preceding posts and I don’t know what you can afford.

We have a whole house Generac generator. It is installed on the side of our house where our furnace is since it runs on natural gas. The battery is internal.

It kicks in about 1 minute after power is interupted and ours is set to self test every two weeks. A maintence check visit by a pro is smart every year which is in the spring for us.

Anyway costs are determined by the size of the house of course. My opinion is it’s all money well spent since of our semi isolated location and our age. It’s a very simple solution.

At my last two houses, I had large generators. In one, I selected a few critical circuits and in the second one, which came with the house, it randomly the entire house. It was old, but it was a beast. It was a 4 cylinder car engine, water cooled running 25KW. I totally agree that a whole house natural gas standby generator is the best. Unfortunately, it's one of those things where I just can't get past the cost even though I can afford it. I can keep my furnace funning so I don't freeze for hardly any money with my small 2000 watt Honda generator. I'd like to upgrade, but to spend $20K just to be comfortable is a hard pill to swallow. I'd do it in a minute if I had something like a medical need but as I sit today, I don't see it being worth it.

The battery solution has the potential to run the few things I actually need for a few hours at a pretty reasonable cost. Plus, I can recharge a battery with my small generator so it's workable. The other benefit to a battery is that I don't need permission from my HOA, which I do for a standby generator. Not to mention, that it's quiet.

Note, that while a battery may only run for a few hours, you don't need to run everything for the full few hours. Even with my small generator, I run the fridge for a while, then the furnace, then the freezer, then the sump pump. So with a battery, that few hours would actually be several hours. Plus, even when I had a whole house generator, I would shut it down at night. There didn't seem to be much point to run the generator overnight with so little actual amps being used. A fridge and a freezer can easily hold temp overnight (6 hours or so) so, there's nothing lost from shutting down overnight. With a battery, I'd take that time to charge.

All of this is informational at this point. Once I get better educated on my options, I'll do something. I'm not too worried about losing electric in the summer, but by next winter, I need a better option to handle my furnace. This time, I undid the wiring at the furnace switch and tied into the furnace from there (isolating any connection that could back feed power). At a minimum I need to hook up a transfer switch at the furnace but I think I'll do more than that.

 

[Steelpony]

At my last two houses, I had large generators. In one, I selected a few critical circuits and in the second one, which came with the house, it randomly the entire house. It was old, but it was a beast. It was a 4 cylinder car engine, water cooled running 25KW. I totally agree that a whole house natural gas standby generator is the best. Unfortunately, it's one of those things where I just can't get past the cost even though I can afford it. I can keep my furnace funning so I don't freeze for hardly any money with my small 2000 watt Honda generator. I'd like to upgrade, but to spend $20K just to be comfortable is a hard pill to swallow. I'd do it in a minute if I had something like a medical need but as I sit today, I don't see it being worth it.

The battery solution has the potential to run the few things I actually need for a few hours at a pretty reasonable cost. Plus, I can recharge a battery with my small generator so it's workable. The other benefit to a battery is that I don't need permission from my HOA, which I do for a standby generator. Not to mention, that it's quiet.

Note, that while a battery may only run for a few hours, you don't need to run everything for the full few hours. Even with my small generator, I run the fridge for a while, then the furnace, then the freezer, then the sump pump. So with a battery, that few hours would actually be several hours. Plus, even when I had a whole house generator, I would shut it down at night. There didn't seem to be much point to run the generator overnight with so little actual amps being used. A fridge and a freezer can easily hold temp overnight (6 hours or so) so, there's nothing lost from shutting down overnight. With a battery, I'd take that time to charge.

All of this is informational at this point. Once I get better educated on my options, I'll do something. I'm not too worried about losing electric in the summer, but by next winter, I need a better option to handle my furnace. This time, I undid the wiring at the furnace switch and tied into the furnace from there (isolating any connection that could back feed power). At a minimum I need to hook up a transfer switch at the furnace but I think I'll do more than that.

I don’t know how old you are or what you can afford but generators do add value to a home upon sale. Ours provides full power for about a 3600 sq ft. home. Our generator cost was about 9-10k.

Ours is mostly a sleep well expenditure. I’d never live anywhere else without one. I did what you’re thinking until I retired though. I’m too old to monkey around anymore in the middle of a severe storm.

Good luck with your decision.

 

[NatureNut]

Long before we sold our house to travel full time in an RV, we had done the following:

1. Installed the maximum amount of solar panel panels our roof could fit (after getting a standing seam metal roof). We didn't have space to add ground mount panels in our little urban lot.
2. Got the most efficient appliances reasonable for the house (since it is generally less expensive to save power than buy battery storage for that power).
3. Insulated the house as well as possible without doing a major retrofit (no tearing apart walls, etc.)
4. Got two Powerwall 2 units to run the whole house when disconnected from the grid.

When the bad ice storms hit Texas years ago and the grid power was out, we were glad we went the solar/battery route instead of a generator that needed fuel.

Fuel was hard to get when the roads were shut down and tanker trucks couldn't make deliveries, and even the natural gas system wasn't working well due to frozen pipeline equipment (natural gas pipeline pressure to homes fell, leading to furnaces not working well). In my experience, backup generators tend to fail at the worst time - when they first try to start up when the power fails.

Instead of needing (and running out of) fuel, we just cleaned off the solar panels. Fuel availability is a huge weakness in using generators during disasters IMHO, which is why I suggest going the solar/battery route and over-size the system to produce more than you need in winter. It may cost more, but you'll also get solar power for your every-day power needs as a bonus.

 

[Global Wizzo]

I used to have a whole house generator but moved and do not have a whole house generator. A recent outage has me thinking about options. I used my small portable gas generator and some extension cords, but that was not something a care to rely on. A friend mentioned a portable battery supply that kept their refrigerator running. That seemed like a good solution, but I want to be able to run my furnace and a portable battery supply won’t cut it for that. I’ve been looking at whole house battery backups (Anker solix and e10), but I just don’t understand them well enough to make a decision. I’m hoping to have a discussion about options and get a better understanding of what I can expect to run with a battery backup and for how long. i.e. can i run my AC? I also want to know if i can charge the battery to extend run time. Can i run my small generator to charge the battery overnight (4 to 6 hours) and extend the battery that way? There was another thread on the battery backup but that focused on leasing the unit. I’m not sure if leasing is a generic option available to the public, but might consider it.

So, how do they work and how does one go about figuring out what to buy.

First thing is look at your electric bill. See what your average daily use is. Mine with a fairly small house is about 31KW during AC season.

The batteries come in various sizes and voltages. 48-52V would be the minimum suggestion for whole house. Tesla power walls are 13KW(?). Been a while since I looked. Many of the batteries are 5KW and you chain them.

In my case a stack of 6 yields 30KW or little less than 24 hours.

With the installation of the inverters, load sheading panels and auto transfer switch you can add/remove loads as needed.

One option is a portable generator set to run the house during the day and switch to battery at night. Set would have to be able to recharge batteries and carry the house load starting with day two.

I just haven’t been able to justify the cost yet. I can throw away everything in both fridges and freezers, move to a hotel and still save money even if I have to do this for several hurricanes.

I do intend to put in a 7-10 day network backup next year so I don’t lose that if I’m traveling.

 

[Diyernh]

I used to have a whole house generator but moved and do not have a whole house generator. A recent outage has me thinking about options. I used my small portable gas generator and some extension cords, but that was not something a care to rely on. A friend mentioned a portable battery supply that kept their refrigerator running. That seemed like a good solution, but I want to be able to run my furnace and a portable battery supply won’t cut it for that. I’ve been looking at whole house battery backups (Anker solix and e10), but I just don’t understand them well enough to make a decision. I’m hoping to have a discussion about options and get a better understanding of what I can expect to run with a battery backup and for how long. i.e. can i run my AC? I also want to know if i can charge the battery to extend run time. Can i run my small generator to charge the battery overnight (4 to 6 hours) and extend the battery that way? There was another thread on the battery backup but that focused on leasing the unit. I’m not sure if leasing is a generic option available to the public, but might consider it.

So, how do they work and how does one go about figuring out what to buy.

I've built a couple of systems for my RV's. LiFePO4 batteries and a Hybrid inverter. I use BattleBorn batteries and Victron Multiplus units. Mine is 12VDC based, but there are 24 or 48VDC systems. My Multiplus 12/3000/120 is only 120 VAC output. They can be paired for 240VAC or even 3 phase.

If you put the batteries and Inverter on a cart, they can utilize a generator connection. You can trickle charge the batteries so they are full when the power goes out.

The Multiplus 12/3000/120 can put out about 6000VA of AC power for a short time allowing it to start up high surge appliances. I programmed it to pull in from a small Honda Generator at 1000Watts. That generator runs for about 8 hours on one 1.1 gallon tank of gas. I can run my RV air conditioner as the batteries/ Multiplus handles the high peak amps, but the Honda just keeps charging at 1000watts.

Essentially, it's what the television ads call a "Solar Generator" but the batteries and components are separate and can be replaced individually.

 

[TickTock]

Interesting rig! We'd like to have something for the whole house to run lights and 5V device charging (pretty insignificant) and AC/Frig/Microwave as needed. DW and I were both electrical engineers, so we can figure loading and power management. Recharging through a generator (yours sounds like a Honda EU1000i ?) and possibly solar panels.

 

[ychuck46]

We have a 20Kw natural gas backup generator for the house and it has performed admirably for many years now during outages (some have been for short periods of time while one bad ice storm in the area caused power to be out here for 2-3 days). Just too convenient to substitute a battery backup unit. Perhaps down the road when the battery technology is even better and longer lasting I might change my mind but for now our Generac NG generator is our preferred approach.

 

[Safe Harbour]

I have a solar (15kW) with 36 kWh of backup battery (all Enphase). I've had it for years. When asked about this as a backup system I have to mention if that's all you want it for it's pretty expensive ($30K after extensive tax credits). Also it won't run a HeatPump (at least for very long outside of peak solar hours). So what would I do for back up. I think today a small battery like 3kW EcoFlow (I have one of these and love it) will keep your fridge and freezer, phones charged, wifi/internet going. You can take it away and charge it or get a portable solar panel. But I would forego a large battery for backup only and instead buy an EV with V2L (Vehicle 2 Load) or V2H (Vehicle 2 Home) capabilities. You basically get a 60kW home back up battery (~$60K worth) for free with your car! The V2L basically lets you run extension cords and power strips to keep things going while the V2H allows you to plug straight into an electrical panel in your home. It's a much cheaper way to cover your home backup needs.

 

[Happy30]

I’m somewhat interested in a whole house backup generator that is fueled by our natural gas line. Installed prices for our sf seem to be around $8,000 - $12,000 around here in the upper Midwest.

This is what are doing! We have a lake house in a rural area in MI and it will give us peace of mind!

 

[Texas Proud]

I know that some have proposed to use a battery with or without solar to arbitrage electricity rates on variable plans..

I looked at some here and every one said that if you used a battery to shift timing that they can come back and charge the highest rate for ALL your usage... IOW, they will not allow you to buy cheap and use when high or even sell back when high...

 

[NW-Bound]

I know that some have proposed to use a battery with or without solar to arbitrage electricity rates on variable plans..

I looked at some here and every one said that if you used a battery to shift timing that they can come back and charge the highest rate for ALL your usage... IOW, they will not allow you to buy cheap and use when high or even sell back when high...

On what basis can a utility company prohibit you from storing energy during off-peak hours, then using it during on-peak hours? I have never read anything like that. It's no different than charging your EV whenever it is cheapest for you, meaning during the day (not at night!).

About pumping from your battery back to the grid, my utility has several price plans. You don't pump power back without their permission, nor will your meter run backwards. They buy your power at 3.45c/kWh, but the lowest rate they sell to you is 3.95c/kWh, going up a lot higher outside of sunlight hours.

And if you have a capacity of higher than 100kW, they have a special agreement for your mini solar farm.

 

[NW-Bound]

My utility encourages home owners to shift energy usage from peak hours to off-peak hours as much as possible. This is for everyone's benefits. It reduces the surge demand on power lines and thermal generation when solar power is not available, and the utility does not have to make expensive upgrades of the infrastructure. It levels out the load, and encourages people to use solar power when it is available, i.e. during midday AND NOT AT NIGHT.

For example, they say that in the summer homeowners should program the thermostat to a couple of degrees cooler than normal to pre-cool the house up to the early afternoon, then raise it during the higher-rate on-peak hours to save money. When the differential rate in mid-summer is as high as 6.61c off-peak and 40.20c on-peak, the saving is significant.

About battery storage which is a recent advancement, they say this:

Benefits of battery storage​

Batteries store excess power for future use and give you greater control over how and when you’re using energy. Depending on your price plan and how your batteries are set up, it may be advantageous to pull energy from the grid during off-peak hours to cover your on-peak usage.

The arbitrage of power rates of course depends on the cost of the battery. My quick and random look on the Web shows that a 5kWh battery can be had for $1350, and with a claim of 6,000 cycles to 80% depth-of-discharge.

Usually the cycle life of a battery is measured to when the battery capacity diminishes to 80% of the original specification. Assuming a linear degradation, the average capacity during a battery life is then 90% of specs. I further assume a 90% round-trip efficiency through the charging/inverting process.

Then, the throughput of the above battery during its life is: 5 kWh/cycle x 80% x 6000 cycles x 0.90% x 0.90% = 19,440kWh. Using the list price of $1350, it works out to 6.9c/kWh.

The operating cost of storage of 6.9c/kWh looks favorable compared to the on/off-peak differential rate of 6.61c and 40.20c. However, this does not include the capital cost of inverters/chargers, the installation, and the opportunity cost, etc... Additionally, this high differential rate only applies in the peak of the summer, and not year round. A more realistic calculation is a bit more involved.

Still, it's intriguing for people who are technically minded, and a good pastime.

 

[Texas Proud]

In Texas you are signing up with an electricity provider... you are signing a contract... they can have in that contract that you do not shift...

Yes, there are now companies that will install a battery for you but they charge a fixed rate 24/7... it is not a variable rate plan..

I have not idea if it is in all plans... I just looked at 2 and saw the same type of language...