I have operated my system as grid tie with battery backup for 13 months. Results have been that I have had a net zero home for that period and produced 850 kwh more than used. This excess was sold back to the utility cooperative. We don't have true net metering, but they reimburse at 70% of the retail rate for every kwh that goes into the grid. I have been studying the cooperative policy and actions for the last couple of years. They are putting all their efforts into killing any regulations of coal plants and forwarding the agenda of nuclear power. Anything they say about renewables is negative or designed to convince people that solar, etc. is something to think about later and not part of their energy plan. Each coop member pays $288 a year to be a member. I learned they are flying board members and executives to Washington to lobby their agenda to kill the Clean Air Act, etc. Although I think we are all in this together I can't pay money to people who work so diligently and wastefully against the energy future we need and against clean air and water. Therefore, since I have a hybrid system and have never needed more energy than I produce (with the exception for a small deficit In Dec and Jan to heat the home which can be accomplished with a small gas appliance)I am considering disconnecting from the cooperative and going off grid. Below is a list of my equipment and my usage and production by month. My batteries have been used mostly just for backup over the last year although they have been cycled a few dozen times or more in offgrid mode as a test. I was wondering if I should double my battery bank with same batteries and if I could put the new batteries indoors right near the inverter even though the others are connected by some heavy wire at a distance of about 15 feet in a box outdoors. I could ventilate the indoor battery box even though they are AGM. Also, what is the smallest, quietest propane powered generator I could use that could be interfaced with autostart Xantrex module. I can actually cut down some of my total usage by swapping my electric tankless hot water heater for gas. We don't use much hot water anyway. Also, am I just nuts to consider this? In 20 years my contribution to the coop would be over $6000. For what? So they can fly around promoting coal and nuclear. Also, one of my solar powered pals a block from here got zapped by a surge from their system for $3000 worth of appliances. That is a risk I don't need. Here is more data for your consideration. Thanks for your advice.

3.8 kw – 21 ea Canadian Solar CS5A-180 3 per string
2 ea Xantrex XW-MPPT-60-150V Charge Controller
8 ea (1520 AH) Deka/MK Battery 8AGC2-DEKA Sealed AGM Battery, 6v 190 AH
Xantrex XW Power Distribution Panel
Xantrex XW System Control Panel (SCP)
Xantrex XW6048-120/240-60 Inverter Charger

Before you pull the plug, have you tried a letter to the editor of the local paper (if there is a local paper?) And how large is the local co-op, that they are able to consider they can influence Washington ? Maybe there is a story there of high rates to sustain expensive trips. A co-op is accountable to the members - which are co-owners.

I have cautiously waited, watched and studied the utility cooperative's policy and actions for a couple of years. I have given them the benefit of the doubt in every way to be sure I wasn't jumping to any conclusions about their motives, etc. I have written letters to the editor of the cooperative's newsletter which is full of stories that are negative on renewable energy. The last one was not answered, and the other answer was defensive and condescending. They don't see solar as part of our energy future. Bottom line is that they take their cue from their G&T who wishes to pursue coal and nuclear. Two years ago the state was giving a $4 a watt rebate for solar. If the coop was interested in their members and renewable energy they could have used their newsletter to encourage members to grab the opportunity for what was a gift of millions worth of solar power. Most of our power here is from coal and is cheap, but the coop's supplier is frustrated because they are finally coming to the deadline to stop polluting set by EPA. If they had been promoting solar we could have made some real progress, but all they do is drag their feet and beg their members to save them from the Clean Air Act by contacting their legislators. With Southern Co., a regional utility giant, spending $10 million a year of rate payers money to lobby in Washington I don't see how executives from this local coop could squeeze in the door past all the pro utility lobbyists. As we speak, the major public utility is trying to sneak a bill through the Florida legislature that would give them complete power to control the PV industry, kill net metering, and completely annihilate the business of solar installers in this state. I do intend to contact the local paper to protest, but I don't intend to pay the cooperative $6000 a year over the life of my PV system so they can waste my money lobbying for the status quo in Washington and bashing renewable solar. I would rather buy batteries and a generator.

I now see that much of the debate about solar is really about getting past the big money from coal, nuclear and the utility companies who don't seem to appreciate solar. It looks like the more affordable solar becomes the more threatened they feel by it. The current bill in the Florida legislature demonstrates that point. In the guise of asking for money to build solar it appears they are trying to completely take it over and neutralize it forever. I never saw the addition of solar to our energy future as a political issue, but now it seems obvious to me after attending the recent coop annual meeting and studying their actions and newsletter for the last couple of years that solar has powerful detractors.

So, if the utilities have their way and I no longer get reimbursed for the 4000 kwh that I put back in the grid what am I to do except try to capture most of it in batteries or at least deprive the entity that wants to steal it by going off grid? If I thought I could make a difference with coop policy I would. They are such a democratic organization that if you ask for your district trustee's phone number they will tell you they don't give out that information.

Back to the original question. If you look at my chart for kwh production and usage you can see that during my times of greatest usage I may use up to 22 kwh per day. I produce about the same. I was wondering if doubling my battery bank to 3040 amp hours and buying a 2500 watt propane powered generator with electric start would get the job done? If so, does anybody have a generator that size they can recommend that is quiet?

Florida is a sunny place. Maybe I don't need to play the grid tie game any more, and maybe I won't be allowed to.

And beware the next step of disconnecting from the grid. The Service Charge you may be billed for the privilege of having power lines run down your street. (Capitol Recovery charge) Or the real kicker, No Electrical Service, so the city red tags your house till you pony up. (regardless of the size of your PV)

Like the bumper sticker says " Beware of Dragons, for you are crunchy and taste good with ketchup"

Small propane genset, I don't know of one. You will have to keep looking. I ended up with a 600 RPM Lister, but it's not autostart.

3040 AH at 48V is a pretty massive bank. I'd suggest wait till your current bank dies, and you will have a better idea of the size needed. There may be some big battery advances in the next few years, and you may find better energy savings in the meantime.
There are problems with both mixing new batteries with old, and many parallel battery strings.

Oh yes, don't forget about your un-permitted lead storage facility and the un-permitted acid containers. Get the locals po'd and they can really make your life miserable.

Should be someone else here to chime in too.

Thanks for the heads up on the dragon. I will proceed cautiously to offgrid mode, but I don't think we have the same restrictions that may exist in your area, yet.

Can you please check my calculations.

8 ea 200 Ah batteries = 1600 Ah battery bank
Divide by 48 = 33 kwh storage
DoD of 50% allows draw down of 16 kwh

16 - 20 kwh is close to being the largest amount I use per day. Of course, most days I am producing 22 kwh during the day. At night I don't use much more than 5 kwh.

If the above is correct then I either need to double the battery bank to give 2-3 full days of storage, and/or purchase a 2500 watt generator. Does that compute? If I follow your suggestion to just use the batteries I have then I can probably go for a few years with them if I have a generator? I am still hoping for a suggestion for a propane powered generator of this size with electric start that can be controlled by my Xantrex XW6048. Just to be sure about options, can anybody confirm the max. battery bank size for this inverter? Thanks a million.

Your battery's are in series, so its 200ah @ 48V = ~9600 watts 100% DOD

If you parallel batteries , the amps add
If you series the batteries, the volts add

Can't do both at the same time with the same batteries

For a XW-6048, that a very small battery bank .. you can kill the batteries in just over an hour at the XW's rated output. Keep in mind the 200ah rating is for a 20 hour draw or 10 amps continuous

Thank you, Solar Guppy,

Obviously I have some homework to do, but I thought previously I had calculated the full charge was only worth about 10kwh of which I can use about half. A thousand pardons, it has been a year since I studied that aspect. Therefore, I need to set the battery capacity on the Xantrex back to 200. I did move the sell amps down to 52 from 55.2 after reading your advice on another thread.

I notice you are from Florida. I have been actively contacting legislators lately trying to make sure the proposed FP&L bill doesn't kill net metering. Supposedly, it is dead, but I look for a last minute amendment sneak attack. I have a real hard time using up the power I make. This month I "sold" about 400 kwh while I purchased 100 kwh. The cooperative pays about 3 cents a kwh less than if we had true net metering. Now FP&L apparently doesn't want anybody to get paid more than avoided cost for being grid tied even if they still will allow it. Hopefully, the bill will stay dead, but perhaps it helps to understand why I want to look at going off grid.

If I produce 22 kwh daily on good days and average about 18 for usage what would you suggest for a battery bank and a generator? Or should I just throw in the towel and spend my time lobbying and writing letters to make sure the net metering rules are kept alive? Thanks a miliion for setting me straight on the battery bank. I need to find a good book on the subject to review. For backup the 200 Ah setup really has done great since I don't use too much power. I have been using the load shave feature round the clock for the last week which has made it where I buy only 1 or 2 kwh a day and sell back about 15. With the sunny weather it hasn't taxed the batteries at all. I love the XW6048.... and this forum.

3.8 kw grid tie battery backup, 21 ea CS5A-180w,2 ea XW-MPPT-60-150V CCs, 8 ea Deka/MK Battery 8AGC2-DEKA AGM (6v 190 Ah), Xantrex XW6048 Inverter w SCP

If I use the XW6048 with load shave feature should I use 2 stage or 3 stage charging from the SCCs? Do I need to input custom voltage settings? I have the charger at the XW6048 off as last thing I want is to buy from grid.

What if I just skip the load shave and max my sold kwh instead of trying to hoard a few in the batteries after using some for load shave? 2 stage or 3 stage? Any suggestions appreciated.

3.8 kw grid tie battery backup, 21 ea CS5A-180w,2 ea XW-MPPT-60-150V CCs, 8 ea Deka/MK Battery 8AGC2-DEKA AGM (6v 190 Ah), Xantrex XW6048 Inverter w SCP