Need info on small solar setups

[punikahakaiferret]

All good info, thank you, DF...I like getting input, opinions, ideas, and especially real-world experience.

It's a jungle out there...and here!

[MarkP]

It's a hassle going to 48 volts but for a house that's what I would do. I have a Schneider Electric 4048 inverter that is good for 3800 watts continuous output and I have never run short of power. My battery bank is eight 6-volt Costco golf cart batteries. I previously had a 3000 watt APC SmartUPS3000 as my inverter. I have a 48 volt DC water pump that runs right off of the batteries.

These days panels are cheap. I would buy a couple more panels before I would shut off the refrigerator.

You are never going to produce power cheaper than the power company can. The draw for me is the "prepper" aspect of it. Same with the water frankly. If I had county water I might still buy a big tank like I have (10,000 gal) and have a catchment system in parallel. That's just me though. I'm weird that way.

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I read another website where a guy who lives in the boonies near Lake Superior was describing his off-grid system including an all-electric oven. He made the point that you have to be happy or you are going to quit and you won't be off-grid or green or whatever lifestyle it is that you are trying to achieve. That makes so much sense to me. Shutting off the reefer is such a compromise compared to the plug and play lifestyle you could have for just a little more investment. Buy all 120 VAC appliances too, not DC. They will be cheaper up front and easier to repair and replace. Life will be easier. All this is possible today because panels are so cheap. I don't hope to run multiple days without sun. I figure if I make it through the night I am good. I will decide the next morning whether to run the generator or wait and see how much sun I am going to get. If the day is cloudy I run the generator.

[kalakoa]

You are never going to produce power cheaper than the power company can.

That depends. HELCO quoted me about $20K to extend the grid to my house, which would have to be permitted, with a licensed contractor doing the wiring...

Definitely 48V for a full house solution. Native 48V LED lighting exists -- put some in the power closet so you can see to work on the inverter.

Panels might get expensive with the latest attempts to "manage" trade, regulators think Chinese panels are being "dumped" through some other Asian countries. It's pretty clear that US manufacturing can't compete but government will keep trying to make it cost-effective.

[punikahakaiferret]

All interesting info, thanks!

I'm into several aspects; not giving HELCO my money, being self-sufficient, but also not paying for more solar than I need for appliances I don't want/use. I like saving money but don't want having more headaches, like batteries that need constant maintenance. I'm willing to pay more for LiFePo batteries that don't need water added or constant babysitting, and don't off-gas.

Really appreciate all the info, everyone.

[MarkP]

I plan to go to LiFePO4 batteries. I regularly kill my lead acid batteries. A great thing about the LiFePO4 chemistry is that they actually like being partially charged. A lot of the hassle of lead acid is trying to avoid prolonged periods of partial charge. There is the temptation to do things like turning off the reefer at night and then the next morning maybe running the generator if it is cloudy, only for the sun to come out in the afternoon. With lithium, just run the generator when you really need it.

[punikahakaiferret]

That's my plan, MarkP; a small system to start with, low maintenance since I'm a real newbie about this...adequate but not excessive panels, controller and inverter, LiFePO4 batteries and a generator (hopefully a Honda EU), and a little bit of propane for cooking. I just don't want to get suckered into buying what I don't need or taken for much more money than I can truly pay right now.

Nope, whoever I can find to help me get this set up is not gonna make much off of me, but I gotta start somewhere.


Thanks for your input!

[MarkP]

I have been a fan of the Honda EU series generators for a long time. My opinion has changed slightly of late. I think as highly as I ever did of the inverter generators but I have become aware of the Honda EM series. Almost as quiet and efficient but with way fewer parts to go wrong and costing way less. Some standard non inverter generators are unstable enough that the solar inverter will reject them and switch back to battery power any time the load changes but the EM series has some tech that keeps the power clean enough to avoid that.

[Durian Fiend]

I plan to go to LiFePO4 batteries.  I regularly kill my lead acid batteries.  A great thing about the LiFePO4 chemistry is that they actually like being partially charged.  A lot of the hassle of lead acid is trying to avoid prolonged periods of partial charge.  There is the temptation to do things like turning off the reefer at night and then the next morning maybe running the generator if it is cloudy, only for the sun to come out in the afternoon.  With lithium, just run the generator when you really need it.

Earlier you mentioned never running out of power, so how are the batteries being killed?  

With enough panels I don't see a need for a generator at all, unless it's for special projects requiring a lot of extra power.

[MarkP]

I meant that my inverter has never shut down due to not being large enough. It will supply 3800 watts continuously, 4400 watts for 30 minutes, and 7000 watts for 5 seconds. It also puts out both 120 and 240 volts. There have been a couple of times where it shut down due to low battery voltage but I had my Low Battery Cut Out set at 48 volts which is pretty high so if I had set the LBCO lower that might not have even happened. The last set of batteries failed because of positive plate corrosion because I had the charging voltages set at the high end of the recommended range and I was gone a lot helping family. Under those conditions the system spent lots of time in absorb and float which overcharges the batteries which in turn causes positive plate corrosion. I will be glad to leave those problems behind.

Part of my overall plan is to get another 6 panels at 350 watts each so I can have a 6 panel array facing east, 6 panels facing south, and 6 panels facing west, all at 45° from vertical. During the summer the south facing panels will not be doing much compared to if they were horizontal but during winter that angle will be perfect. The east and west facing arrays will generate useful power from 7am through 6pm during summer and in a manner analogous to the south facing panels they will not be doing too much off season. During cloudy periods the angles don't matter nearly as much and the sheer square footage of "extra" panels will make up some of the difference. I have invested in multiple charge controllers so the question of whether putting east facing and west facing arrays on the same controller will work need not even be addressed. Multiple units also serves as redundancy, keeping you going if lightning takes out some of your system.

[MarkP]

There were times that I was pushing 60 amps into a string of 210 Ah golf cart batteries. Recommended charging rate is .05 to .13 of the amp-hr value so 60 amps is 2 to 3 times the recommended charge rate. The charge controller goes by voltage to say when the batteries have charged enough so charging them at a high rate, which requires extra voltage to push the extra current through, satisfies the charge controller algorithm too soon. Depending on sun conditions and power use, you can be alternately over-charging and under-charging your batteries. The last set of golf cart batteries that I killed had to live through a period where I was changing over from an APC UPS3000 to the SW 4048. I also did a lot of work on the solar arrays as well. There were a couple of weeks where they were horribly undercharged and shut off due to low battery voltage a couple of times. That is low voltage as defined by the UPS. UPSs sacrifice the battery bank to serve the load they are protecting so that killed that bank extra early.

At this point I probably know enough not to commit any further battricide but I am ready to move on.