Max charging amps?

[Bessy765]

Hi all, I have two 95 amp AGM batteries, looking to eventually have two 100 Lithium, 3 x 175 watt solar panels, and a Victron 2kw inverter charger. Thinking about installing the solar first myself just wondered if the three panels and mppt regulator may be too much for the two 95 amp AGM’s. To handle. Also got plenty of room on the roof for the panels but one of which will be shaded by the sat dish when in use, so thinking the best way to connect them series or parallel.

 

[autorouter]

3 x 175W is 525W. If they are fitted flat on the roof (not tilted) then you'll be lucky to get more than 80% of the rated power, so that's 420W. If the charging voltage is 12V then the current will be 420/12 = 35A. You'll need an MPPT controller with an output of 35A or more.

2 x 95Ah batteries is 190Ah total. The usual rule of thumb for lead-acid batteries is to limit the amps to less than C/5, where C is the capacity. So that's 190/5 = 38A.

So it looks like those panels will be fine for the 95Ah batteries, especially since the 35A will be a peak when the sun is strongest, and will often be less than that.

For Lithiums that's not a problem, not even for just one battery, so two will be fine.

 

[autorouter]

Also got plenty of room on the roof for the panels but one of which will be shaded by the sat dish when in use, so thinking the best way to connect them series or parallel.

Installations on motorhomes are nearly always in parallel. Especially if one of the panels might be shaded. If they're in series, then a bit of shade on one panel reduces the output from all of them. In parallel it just affects the one panel.

 

[donkey]

Only yesterday I was checking a few things in the motorhome and thought the solar output was a bit lower than I expected. The sun was shining at about 14:00 hours.
Decided to close up, shut both roof vents, went to pick up my tablet and noticed quite an increase in solar output.
Because of the way the vehicle was pointing, each roof vent shaded one solar panel. I re-opened each in turn and was very surprised by just how much a clear acrylic panel affected the solar output.
I don't think it will be an issue on site as we tend to park facing west-ish, so the vents will be behind the solar panels.
Geoff