Steve Spence said:
If one wants to use 24volts as the system voltage, then:
16 12v 220ah batteries would indeed give you 1760 ah total storage, or 880
ah usable.
16 6v 220ah batteries would indeed give you 880 ah total storage, or 440 ah
usable.
Again, this is assuming the batteries are really 220ah, which is in
question.
In fact they are 210ah, 6v. The models that I bought about 4 years ago were
220ah.
They are made by the same manufacturer, but for some reason the newer models
are 210ah. I'm building a 48v bank. My 4 6v batteries x 220ah @12v bank has
served me well, and will continue to serve in a seperate small utility role.
2 6volt batteries at 220ah each in series is still only 220ah. In series
voltage would double, in parallel amps hours double. Watt hours stay the
same in either case.
And it's the watt hours that matter. This should be plenty for me for the
immediate future (3-4 years?) and a little beyond. I want to avoid the
desire to add capacity half way through the life of the bank. The budget
will bear $800, so that's the bank size.
The bank is sized based on my available budget and not necessarily on a well
balanced system design. It is actually a larger bank that I presently have a
need for, but I do anticpate that I'll increase my needs within the 7-10
year lifetime that I anticipate to the bank. If I cycle this bank less
deeply now, then maybe I will get a bit longer life out of it. I figure it's
better to oversize the bank (for immediate needs) than to undersize it. If I
have made a miscalculation in bank size, it would be to have made it too
small and not too large as some focused on amp hours seem to imply.
At 600watts, my array is undersized to both the bank and the inverter, but I
expect to add to the array incrementally in future years and reduce the need
to run the generator.
The SW4048 inverter will probably be all I ever need. I have actually
downsize this from a desire for a SW5548. I want sine, and generator
control. That seemed to be the entry point model for those requirements. I
like Outback, but they are too new to have much of a used market. I got a
great deal on a remanfactured SW4048. I'll probably be running on the lower
end of capacity, and also efficiency, but it has the features I wanted, the
price was right, and I will not have to thrash $ in incremental upgrades.
At some point to you have to get out of analysis and justification mode and
just go do it. That time for me is now.
The bank, inverter, panels, and generators are essentially a done deal. All
I need now is some wire, a dc disconnect, charge controller and the time to
wire it up and I'm up and running. I suppose I could add batteries within
the next year if it turned out to be undersized.
I ponder an $600 Outback MPPT controller, vs a cheak C40 charge controller.
I think I'll experiment with the C40, and upgrade to a MPPT only if
necessary. Tha may be an incremental upgrade for the future.
I am sure it will all work quite well for my needs. If not, I'll make
adjustments.
I doubt that I can brag to the world that it is the best designed system,
most efficient, or most economically viable. But, I'm done pondering, and
I'm now I"m assembling.
By next month, the new system will be providing my power.
