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HI, I tried the search feature, being new here, but didn't find what I wanted to read. IF you were given 6 new 6 volt 230 ah golf cart batteries, how would you hook them up to create a small solar system. All I'm looking to do is to have a standby emergency light set up with the ability to run a small microwave [well under 1000 watts]. If possible, I may experiment to use them to run all lighting in my house, all CFL/LED types all the time to see if there is a worthwhile effect on my electric bill. From camping, I have 3 inverters. 140/700/1500 watt styles. I was scanning the net for panels and saw Renogy, 100 watt mono panels at a reasonable price, but again, I don't know how useful they would be. Are they junk or good? I could run a 120 volt battery charger [am open to suggestions on a good one for this purpose. I currently have Battery Minders and Tenders and an old automotive 10 amp 6/12 volt type] and have access to generators, but they of course need fuel. It would be nice if solar panels could recharge the batteries daily, but in my area, I don't think that will happen. I may have to result in utility powered chargers and thus defeat my purpose. If this makes any sense. I have a manual transfer switch already on the house that I could use a generator to feed OR an inverter to feed so I can time share the load when necessary simply by unplugging the cord from the genset and plugging in the cord from the inverter or vise/versa in a blackout scenario. I was thinking the 140 inverter would be the one to run my lights and would be the best at efficiency, IE, not eating up much power just to power the inverter electronics. I am going to connect an ammeter to each to test each inverter in the 'on' position; how much does it consume in the 'stand by' condition, to gather some data on that subject. I live in the northern/eastern part of the States, so I'm not exactly being toasted in sunlight every day. I am capable of hooking up any system in series/parallel or combination of both. I am familiar with electrical materials. Designing a solar system is new to me. I will comment on both the Battery Tender and Battery Minder, I can't see them being used to recharge a bank of gc batteries since if the batteries were drained somewhat, they would take 2-3 days @ 24 hrs to recharge them, if I'm lucky. They work great on my bike battery and seldom used car. Thanks in advance for any opinions offered.
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Couple of things you need to know. For 6 of those batteries are you are looking at a minimum panel wattage of 900 watts to support the batteries assuming you live in an area with at least 3 Sun Hours in Winter. More if you live in an area with less than 3 Sun Hours in winter. At this power level using 100 watt battery panels is out of the question due to expense, you would use 250 watt Grid Tied panels and a MPPT Controller. So you are looking at around $2000 to $2500 investment in panel, wiring, controller, and inverter, plus rewiring your home cost.
Just because you got the batteries free does not mean electricity is free. Those golf cart batteries you have now will need replaced in about 2 or 3 years. Just based on battery replacement cost alone you are looking at roughly 60-cents per Kwh which is likely much higher rate than the power company charges you.
With 6 batteries you are kind of screwed because you can only configure them for 12 volts which suks. 12 volts is for toys and RV's, not home installations. Ideally you would want to run either 24 or 48 volts. You would need to loose two batteries for 24 volts, or gain 2 batteries to run either 24 or 48 volts.MSEE, PE -
Hi Sunking, thanks for your response. I have no interest in dumping a small fortune into solar due to my area; low is 1.45 sun hrs/day in winter. I was curious about cost per watt, knowing full well with the research I've done, solar is not cost effective as a source of power vs a utility. IMO it would only be good for an off grid cabin or total blackout for a period of time since gas stations wouldn't be available for generator fuel. I think the chances of that are slim in my area. There have been summer storms that took out power for 6 days near me in isolated neighborhoods due to tree falls, but I had power. Since I have the batteries, inverters, and the house is wired with a generator xfer switch, I can easily use the batteries for a 'quiet' energy supply at night and generator during the day to run lights. I don't have to rewire anything in the house. the only thing I may purchase is a better AC charger for the batteries. The generator could run my house while the batteries recharge from the generator for night use if need be in an emergency. Do you have an opinion on chargers that can be used for this purpose and can equalize? Thanks again for your response.Comment
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OK with a genny you don't need a solar for backup power.
There are a number of chargers on the market you can use. But for a 12 volt charger in the size you need for those batteries is a bit pricey. With a 12 volt 690 AH battery will need a 70 to 100 amp charger. I suggest either loosing two batteries to make a 24 volt 460 AH battery with 40 to 50 amp charger, eor buy 2 more batteries for a 48 volt 230 AH battery and your standard cheap golf cart 25 amp charger.
One more thought occurred to me. You can make your battery 36 volts @ 230 AH, and use a cheap 36 volt 25 amp charger. The challenge would be to finding a 36 volt inverter.MSEE, PEComment
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The source for a 36v charger would be a golf cart supply. Many of them run 36v systems.
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