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glennts's avatar
glennts
Explorer
Apr 12, 2020

Puzzeling thru a 12v to 24v solar upgrade

Currently have 400w of 12v panels feeding four 6v US Battery 2200's in series/parallel.The 12V battery output goes to a 1000w inverter dedicated to a single plug output for computers. There is a Blue Sea combiner that flows between the coach battery or back when on shore / generator and the panels are sleeping. And a TM 2025-RV. A simple and effective setup.

Now upgrading to 3 Hanwah Q Peak 325W panels that will feed into a Tracer 4210AN cc that replaces a Rogue cc which died after years of good service. So the questions that arise are (A)to allow the MPPT to down convert the 24v input to 12v and keep everything else as is. Or (B)to switch the batteries to a four 6v series 24v bank. A 24v bank complicates the Blue Sea combiner arraingment and obliges me to either buck the 24v output down to 12v to use the existing 1000W inverter or simply get a 24v / 2000W inverter.

If I lose the charging flexiblity advantage gained by the Blue Sea combiner, would I gain it back by tying a 24v / 2KW inverter into the RV's PD distribution panel and letting the solar panel output find its own way to the coach battery. A further gain from this would be from also having the solar output be available for general AC distribution. If the 24V inverter output is tied into the house distribution panel is there a better way other than manual switching to insure there is no conflict when the AC source becomes generator/shore power? Also, is the Blue Sea combiner which allowed current to flow from the shore power charged house battery to the solar bank now useless? I can see how stepping up the voltage on the solar bank side on the combiner might allow for some use but the combiner relies on voltage monitoring for its switching and that would no doubt be compromised with step conversion. Is there a way around this that would allow for generator / shore power to be available to charge the solar bank?

And, as a secondary issue. If the batteries are to be re-aligned to a 4 s string for a 24V bank. Two of the batteries are 2 yrs older. Is there any consideration to be given as to the order in the series. Older ones in the middle? Older ones at the ends? Alternating? Does it matter? They will be balanced out before re-connecting. When these batteries are past their usefulness in a year or two I'll probably go the re-purposed Tesla car 24V Lipo battery route.

Any input will be appreciated. Thanks.