House Battery Backup

joliver

I live in Utah where it can get cold for extended periods of time during the winter and I want to avoid being so utterly and helplessly dependent upon the grid during any extended outages that may occur. I'm not particularly concerned with solar panels at this stage. Basically I'm looking at doing a full house UPS for critical loads (obviously, air conditioning and other power-hungry luxuries would be excluded). Generally speaking, I was hoping to have a setup of something like this:

During normal grid-available operation, a bank of batteries is topped off and fully charged by the grid. When the grid becomes unavailable, the "system" automatically fails over pre-selected/isolated critical circuits to available power from the battery bank. When the battery bank reaches a certain threshold (hopefully after many hours or perhaps even days depending upon the load), the system sends a start signal to a generator. The generator recharges the batteries to optimal levels and then shuts down. The battery bank discharge and generator recharge would then occur until grid power is restored OR fuel is exhausted, which ever comes first...

Here's what I'd like help with at this early phase. I'm looking for resources such as posts on this forum and other forums that show/spotlight:
1. The critical components of such a system,
2. First-hand experience with a system similar to mine,
3. General guidance to the process of building such a system,
4. List of gotchas or things to watch out for.

Also, at this stage, I'm not terribly concerned with things like Generac vs Honda or diesel vs propane or gel batteries vs sealed batteries, etc. I understand some of the basics of power such as volt, amps, watts, and conversion back and forth, but I'm sure I'll have more questions...

My budget is around $10K-$15K for the project. My house is 4K sq/ft and my power usage averages 33kwh/day or about 1,000kwh/month.

Thanks in advance for any advice/pointers.

niel

Re: House Battery Backup

welcome,
you will find a backups to be good on key select ac circuits and you will need to know the loads you will have running on this setup, even if you aren't there as it would be automatic with a automatic transfer relay. these are built into many of the major inverter/chargers. i have such an inverter charger being a magnum mms1012. you may prefer something a bit bigger in wattage and battery voltage depending on the loads you run and the autonomy involved and all of that will determine or influence your battery size too.

basically, you'd have the inverter/charger with a built in autotransfer relay that has the option of a remote generator start with a generator capable of remote start and of course your battery bank. magnum does have a great selection for this purpose and is, of course, not the only one who does. all of this will be in general until specifics are known about the loads you plan on running and for how long as you will need to know the kw max draw and the rough kwh total you'll need before switching to generator power. systems like you propose are common and lend themselves well for solar later with a bit of hindsight.

ggunn

Re: House Battery Backup

joliver wrote: »

I live in Utah where it can get cold for extended periods of time during the winter and I want to avoid being so utterly and helplessly dependent upon the grid during any extended outages that may occur. I'm not particularly concerned with solar panels at this stage. Basically I'm looking at doing a full house UPS for critical loads (obviously, air conditioning and other power-hungry luxuries would be excluded). Generally speaking, I was hoping to have a setup of something like this:

During normal grid-available operation, a bank of batteries is topped off and fully charged by the grid. When the grid becomes unavailable, the "system" automatically fails over pre-selected/isolated critical circuits to available power from the battery bank. When the battery bank reaches a certain threshold (hopefully after many hours or perhaps even days depending upon the load), the system sends a start signal to a generator. The generator recharges the batteries to optimal levels and then shuts down. The battery bank discharge and generator recharge would then occur until grid power is restored OR fuel is exhausted, which ever comes first...

Here's what I'd like help with at this early phase. I'm looking for resources such as posts on this forum and other forums that show/spotlight:
1. The critical components of such a system,
2. First-hand experience with a system similar to mine,
3. General guidance to the process of building such a system,
4. List of gotchas or things to watch out for.

Also, at this stage, I'm not terribly concerned with things like Generac vs Honda or diesel vs propane or gel batteries vs sealed batteries, etc. I understand some of the basics of power such as volt, amps, watts, and conversion back and forth, but I'm sure I'll have more questions...

My budget is around $10K-$15K for the project. My house is 4K sq/ft and my power usage averages 33kwh/day or about 1,000kwh/month.

Thanks in advance for any advice/pointers.

Look at the SMA Sunny Island. It can manage your batteries from the grid and start and stop the generator at programmable SOC setpoints, and you can add solar to it later with SMA Sunny Boy inverters that communicate with the Sunny Island which regulates their output to keep from overcharging the batteries when you are running off grid. It's a pretty slick system.

Rick1

Re: House Battery Backup

joliver wrote: »

I live in Utah where it can get cold for extended periods of time during the winter and I want to avoid being so utterly and helplessly dependent upon the grid during any extended outages that may occur. I'm not particularly concerned with solar panels at this stage. Basically I'm looking at doing a full house UPS for critical loads (obviously, air conditioning and other power-hungry luxuries would be excluded). Generally speaking, I was hoping to have a setup of something like this:

During normal grid-available operation, a bank of batteries is topped off and fully charged by the grid. When the grid becomes unavailable, the "system" automatically fails over pre-selected/isolated critical circuits to available power from the battery bank. When the battery bank reaches a certain threshold (hopefully after many hours or perhaps even days depending upon the load), the system sends a start signal to a generator. The generator recharges the batteries to optimal levels and then shuts down. The battery bank discharge and generator recharge would then occur until grid power is restored OR fuel is exhausted, which ever comes first...

Here's what I'd like help with at this early phase. I'm looking for resources such as posts on this forum and other forums that show/spotlight:
1. The critical components of such a system,
2. First-hand experience with a system similar to mine,
3. General guidance to the process of building such a system,
4. List of gotchas or things to watch out for.

Also, at this stage, I'm not terribly concerned with things like Generac vs Honda or diesel vs propane or gel batteries vs sealed batteries, etc. I understand some of the basics of power such as volt, amps, watts, and conversion back and forth, but I'm sure I'll have more questions...

My budget is around $10K-$15K for the project. My house is 4K sq/ft and my power usage averages 33kwh/day or about 1,000kwh/month.

Thanks in advance for any advice/pointers.

Your going to need a lot bigger budget unless you give up on the batteries? My battery cost estimate for three days of 33 kwh was over $12,000.00. then you have to add the cost of charge controllers, plus inverters, plus hardware and labor.

ggunn

Re: House Battery Backup

Rick1 wrote: »

Your going to need a lot bigger budget unless you give up on the batteries? My battery cost estimate for three days of 33 kwh was over $12,000.00. then you have to add the cost of charge controllers, plus inverters, plus hardware and labor.

My advice would be to pare down to the bare essential "hunker down" power needed in an extended outage, move those loads into a protected loads panel with a disconnecting transfer switch and the generator, battery inverter, etc., and size the system accordingly. That might mean moving everyone into a single room for the duration of an outage, leaving off TV and stereo, reading by candlelight, etc., to get the usage down.

peakbagger

Re: House Battery Backup

Outback Radian all in one package or a system based around a sunny island (I think midnight solar may be coming out with a packaged unit). Unfortunately there is no cheap way out.

niel

Re: House Battery Backup

slow down guys as he did not say he wanted to maintain the 33kwh.day status quo. now i'll grant you he still has to determine what it is he wants backed up and for how long, but i think he can get his critical circuits backed up for a bit of time before needing the generator to start. it should be doable with the money he proposes.

stephendv

Re: House Battery Backup

I may be stating the obvious here, but the other variables you need to consider are how frequent the power outages are and how long they last. You can then have a spectrum of options based on how much battery you need and how reliable your generator needs to be. With short and frequent outages, you could invest in a battery that covers the outage entirely then recharge when the grid comes back up, so you don't need a high quality generator. With short infrequent outages, don't bother with the batteries at all, just an inverter-generator would be a better investment. For long outages, a big battery becomes too expensive especially when it's not being used 99% of the year- in that case you may need a good quality generator and no battery. For a mixture of the above, e.g. infrequent long outages and frequent short outages, get a battery to cover the short ones and a good quality gen for the long ones.