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  • back up battery bank to run home essentials

    hello, all. i have been looking into building a backup battery bank in my basement to feed through an inverter and backfeed my electric panel in a power outage. my first step is building the battery bank system, and the second step is configuring a solar panel setup outside for charging. i am looking to just be able to run my fridge a few hours a day, and run my well pump as needed for water. my well is deep (420'+) and i have a 1.5 hp well pump (grundfos 5S10-22) using 10 running amps and 35 surge/start amps. i would also be using power to charge/run electronics/rechargeable batteries etc. i would only be using this system in an emergency power failure situation. i was looking at the AIMS 6000 Watt split phase inverter. i figured i could shut off my main breaker in the panel cutting off utility power, and feed the battery power bank through the inverter and into the electric panel of my home via 6amp breaker to run the well pump and other circuits.

    i am having trouble figuring out if i should design a 12/24/48 volt system? it looks as though 24v or 48v are better for higher volt inverters from what i have been reading? also, how many volts of solar panels would you recommend for charging the batteries?

  • #2
    Howdy t0mmy91 and welcome to Solar Panel Talk. First step is to determine how many watt hours or kilowatt hours the system needs to deliver, until you have done that no one can really help that much.

    I suggest you start reading the stickies in the off-grid section that should get you clued up as to where to start, good luck. P.S for a house type situation it will most probably have to be 48 volt

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    • #3
      Originally posted by t0mmy91 View Post
      hello, all. i have been looking into building a backup battery bank in my basement to feed through an inverter and backfeed my electric panel in a power outage. my first step is building the battery bank system, and the second step is configuring a solar panel setup outside for charging. i am looking to just be able to run my fridge a few hours a day, and run my well pump as needed for water.
      First off you should not use batteries unless you absolutely, positively need them. They are a pain in the butt. Generators work a lot better. So unless you are having multi-hour outages a week, I'd go with something far cheaper (a generator.)

      If you have (or are going to get) a grid tied solar power system, then consider an SMA system with their Secure Power system. It gives you up to 2000 watts during the day. So with that plus a generator you will reduce your generator's run time and still have backup power; you can even say it's solar. If you never want power interruptions to critical equipment, computer UPSes are cheap and easy to use, and thus the pain of regular replacement isn't that great.

      If you still want batteries you have to figure out your maximum load (in kw) your starting requirements (also in kw, or better yet, kVA) your voltage requirements (120? 240?) and your desired energy storage (in kwhr.) It would also help to know frequency of use. Then you can start designing.

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      • #4
        Really horrible idea. With batteries your are extremely limited in power, and you do not even want to know the economics of it. Get a whole house generator powered eith with NG if you have NG or LPG. No limitations in power, run everything at a fraction of the cost. You do not have to replace a generator every few years like batteries. Batteries will cost about the same or more than a generation. In the end using solar and battery for emergency power is economic suicide. Wil cost you many times times more than a generator, some 10 times or more. With batteries very limited power. Just lights and some bare essentials. Generator every thing like nothing happened and more reliable

        To run a 6000 watt Inverter with batteries requires a 3000 pound $8000 battery you replace every 5 years rather you use it or not. Is that what you are looking for? I hope so because that is what you are asking for. That does not include anything else to make it work. A generator is less expensive, a lot less expensive an ddoes not replaced in 5 years except the starter battery for $100 every 5 years.
        Last edited by Sunking; 01-01-2017, 11:27 PM.
        MSEE, PE

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        • #5
          There are worse Hobbies, aren't there ? I know you guys are giving good advice, and some people's questions are really not researched. But isn't a properly maintained hobby (cycled) offgrid system 1 option for some backup power. Any hobby that betters yourself or your preparedness is a beneficial use of time compared to some gas burning , time consuming activities?

          Comment


          • #6
            Originally posted by Brian53713 View Post
            There are worse Hobbies, aren't there ?
            Sure if you call sinking $10,000 + into something that you will loose does not sound like a hobby to me. I would think going to Lost Wages and loosing $10,000 at the tables is a better hobby and a lot more satisfying. Sound more like a nasty bad habit like smoking cigs/ganja or drinking alcohol. In your case even illegal.

            Look I am not trying to be hard on you, but look what has happened so far. Solar Pete is a solar biz owner who would love love to make that sale, and two experienced engineers have told you how bad the idea is. If you insist they both might help you. As for me, I would tell you the same thing i would a prospective client if you insist on doing this, go to my competitor down the road. Who you doing to hire to do your hobby putting 3000 pounds of lead in your basement?

            You cannot just use a breaker to cut-off a utility in a power outage. It takes a special peice of equipment you are not qualified to install and requires a PERMIT. Those 3000 pounds of batteries require not only local permits and inspection but you get to also deal with Employment Prevention Agency mountain of red tape, regulations,fees, yearly inspections from the fire department, and spill containment in place. Once you crossed the 500 pound mark in electrolyte, your neighbors and first responders want to know who is putting their lives are in danger and with what.

            Sure you can try to do a Gorilla Install bypassing all the rules and regulations. But if you were to ever get caught, you are in deep poopoo. If you get caught because of a fire and someone gets hurt, you wil go to jail for a long time and loose everything you own or ever will own. Put those neon lights and strobe light up called solar panels, your electric company is going to notice and wonder why you do not have a contract with them or any inspections from your local building code enforcement agency.

            If you proceed as you plan is not going to end well for you. You have three pro's telling you so. Never going to happen. Sorry to be so blunt, but you do not even know enough to ask good questions. What you have learned so far should send you running.
            Last edited by Sunking; 01-02-2017, 12:47 AM.
            MSEE, PE

            Comment


            • #7
              Originally posted by Sunking View Post
              ....Those 3000 pounds of batteries require not only local permits and inspection but you get to also deal with Employment Prevention Agency mountain of red tape, regulations,fees, yearly inspections from the fire department, and spill containment in place. Once you crossed the 500 pound mark in electrolyte, your neighbors and first responders want to know who is putting their lives are in danger and with what........
              Do they really regulate homeowner battery installs, or only commercial installs. I know my area does not (or did not when the inspector was out inspecting)


              So, back to t0mmy91 . So, I'll make a short simple list of what you could use to run the Fridge, couple lights, sump pump and well pump, using gear I have.

              48VDC system, pump motors suck a lot of power

              XW 6048 hybrid inverter, 120lbs $3500 Robust, beefy 6Kw split phase inverter/charger w/transfer switch (will recharge batteries from grid or generator)


              2 days labor, 1 Electrician to install sub panel for critical loads, E-Panel for inverter, wire batteries, wire inverter, generator etc etc $1500+

              Batteries. Gotta figure loads first, Assume you have an "average" fridge, consumes 2Kwh daily, Pump, assuming 30 min runtime daily. 1500kwh
              Misc lights & radio & a table fan = another 1500kwh. So, power is up to 5kwh consumed a day in emergency conditions.
              (It's a fallacy to think you can just run your fridge a few hours a day, it will run constantly for those hours trying to cool back down, leave it going as normal, limit door openings to save power.)
              Since this will be only emergency backup and not daily cycle battery, you can use the minimal size battery to start your loads (the Pump) That 240V 35A surge (8,400watts) has to come from batteries, any cheap money saving tricks will not start the pump when the batteries are 3 years old. A 48V bank will have to deliver 210 amps for a second. If the batteries are older and cables getting nasty, you loose a bit more capacity. And the inverter will require a minimum of 100ah battery per each Kw load. So I'm thinking about a 400ah battery bank is about the smallest you can get away with, and still be reliable, That gets you to a L-16 case size (6v, 350ah) and you need 8 of them for a total of $3,000 - replaced every 5-7 years.

              Generator - If you have batteries, you have to have a generator, Here, you can save a bit of cash, since the inverter can provide generator support, if it needs to start a heavy load, it pulls extra power from the batteries to assist the generator, Awesome to see it happen. Something in the 4 or 5KW range, with 240VAC output would work.
              Fuel type = your preference, Generator $2500

              To add solar, it's just PV panels, racking, and the PV Charge controller. Figure about $4watt whatever size you want to go with,


              Hope this helps, we're saving money here, not selling pie in the sky hopes that will fail you.





              Last edited by Mike90250; 01-02-2017, 07:32 PM. Reason: 6Kw not 60Kw inverter
              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

              Comment


              • #8
                Originally posted by Mike90250 View Post

                Do they really regulate homeowner battery installs, or only commercial installs. I know my area does not (or did not when the inspector was out inspecting.
                Do the Electrical Inspectors regulate it? Probably not. Not their job. Will the relevant enforcers of toxic material codes enforce it IF they manage to find out about it? Probably.
                SunnyBoy 3000 US, 18 BP Solar 175B panels.

                Comment


                • #9
                  Hi guys, thanks for the helpful responses, especially Mike 90250. i do have a large generator that runs the house, its a Generac 17,500 kw gasoline generator.. it guzzles gas and i am looking to use that as a last resort as a few times the gas stations have gone empty quickly when there is a 2 day outage from weather etc. i do not have any nat gas in my area. i doubt there would be any inspections etc from my area, so not really worried about that. i just purchased a "kill a watt" device to track the usage of the items i want to run. i also have an electrical clamp that i got the well pump run info from.

                  the point of this would be looking to be able to run the few needed things in my home for a few weeks if needed without grid power.

                  Mike 90250, how many watts of panels would you suggest to charge the system you provided above, anticipating a longer outage without grid power? and thanks again, i appreciate your helpful response above.

                  also i guess it would be another option to get a manual well pump as back up and scale down the solar system for only 110 use for the fridge and other items.
                  Last edited by t0mmy91; 01-02-2017, 07:39 AM.

                  Comment


                  • #10
                    Originally posted by Brian53713 View Post
                    There are worse Hobbies, aren't there ? I know you guys are giving good advice, and some people's questions are really not researched. But isn't a properly maintained hobby (cycled) offgrid system 1 option for some backup power. Any hobby that betters yourself or your preparedness is a beneficial use of time compared to some gas burning , time consuming activities?
                    Hobbies can be both fun and expensive. An off grid system or battery powered backup is not a hobby, it is a job that requires a lot of attention to maintain as well as money.

                    If you are looking to run small electrical loads and don't mind spending your money then a solar / battery backup system might be useful. If you plan on running house appliances (frig, AC, water pumps) for any extended time due to a power outage then the costs take it out of the range of a hobby and into a major investment with little to no return on what you invest.

                    I am all for being prepared for a power failure. I do live in Florida and we can get one of those hurricane things. But before anyone spends their money on a solar/battery system they really need to understand the physics and economics of what it needed to build the system correctly.

                    Comment


                    • #11
                      Do you actually want to learn something with this hobby? I have a summer home which is off grid, has about 1,200W of panels and a single car battery to run everything. That gives me lights, TV, refrigeration and hot water. My wife and I live there for 4 months every summer and don't feel deprived at all. Yea, it's a hobby. Just to see if it can be done. Paid for itself in six years. It can be done with a few lifestyle changes and a number of tricks. Everything is scheduled and prioritized by microprocessor. No electrons are wasted. Can you do it? Probably not, but you could if willing to take a major effort. Being able to turn on everything just when you want to takes a lot of power from a big dumb system. Scheduling will be the future of energy whether grid or RE.

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                      • #12
                        Get a smaller generator and learn to use a lot less energy, in general and especially during power fail situations. Even without solar, our 2000 sq ft modern home uses half the energy of our neighbours. If you add solar add grid tied panels. if You must have batteries consider a hybrid system to give enough emergency light to get the appropriate generator started.

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                        • #13
                          Originally posted by Mike90250 View Post
                          Do they really regulate homeowner battery installs, or only commercial installs. I know my area does not (or did not when the inspector was out inspecting)
                          Yes Mike both UBC 307 and UFC 64.xx. Goes a little further too requiring seismic bracing, occupation separation, ventilation. neutralization, warning signs, and even structural requirements. Catch is if your AHJ has adopted the rules.

                          Originally posted by Mike90250 View Post
                          XW 6048 hybrid inverter, 120lbs $3500 Robust, beefy 60Kw split phase inverter/charger
                          Mike did you mean 6 Kw?

                          MSEE, PE

                          Comment


                          • #14
                            Originally posted by t0mmy91 View Post
                            Hi guys, thanks for the helpful responses, especially Mike 90250. i do have a large generator that runs the house, its a Generac 17,500 kw gasoline generator...
                            No one has caught all this. Your only mistake was getting a Gasoline Generator. Stationary generators should not be gasoline because gasoline becomes stale in 6 month so cannot be stored an din short supply during natural disasters. That is why people and pros use NG/ LPG, or diesel. Convert your generator and you get what you want.
                            MSEE, PE

                            Comment


                            • #15
                              Originally posted by t0mmy91 View Post
                              Mike 90250, how many watts of panels would you suggest to charge the system you provided above, anticipating a longer outage without grid power? and thanks again, i appreciate your helpful response above..
                              48 volt 400 AH battery requires 4000 watts.

                              MSEE, PE

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