Solar panel question again

well, it all depends on which controller you use ;-)

To get _maximum Amps_ into the battery bank (from a given solar array), will require the use of a MPPT controller, and some of these will accept quite high (input) voltages...

I have a Morningstar Sunsaver (15A) MPPT which has a max input 75V, and with 4x 40W panels, I connect em parallel/series.. i.e. 2 sets of 2 panels in parallel, then the 2 "strings" in series.. This gives about 40-something volts at the reg.

The big advantage of the series/parrallel config (as I see it) is that even in very low light, the input voltage, even when reduced by half, is still well above battery charging voltage, so the battery still receives some charge..
Another advantage is that you can use lighter cable between panels & reg..

Works for me ;-))

:)

Duane,

Ed's 100% right IF you use the type of controller he refers to and IF you connect it up the way he has. (I believe batteries in parallel and pairs of the the 60W panels connected in series, then the two pairs of panels connected in parallel.) BUT with most controllers you cannot do that. The energy coming from the panels equals the current multiplied by the voltage and Ed's smart controller actually trades off one against the other to provide a maximum energy transfer into the battery. Most controllers do not do this and simply pass to the battery all available current until the battery voltage rises to a preset maximum safe level, when the panels will be disconnected by the controller.

Unless you want to go to an expensive controller like Ed's I'd suggest connect all your panels in parallel, all your batteries in parallel and fit the controller close to the batteries so as to minimise losses between controller and batteries.

An option you might consider - I carry several batteries but only one is working at any one time. Very easy to achieve, and overcomes the losses which can arise if a sick battery is permanently in parallel with good ones. To safeguard against fire (and protect the batteries) each battery should have a fuse as close as possible to the battery. With all fuses in place you can have all batteries in parallel. Remove one or more fuses and you isolate their battery/ies. The unused batteries must be kept charged, but this is a very flexible way of carrying spares which can be brought into use simply by inserting a fuse.

HTH

John

The power is the same whether you have the panels connected in parallel or series.

If you have a PWM Controller you have no choice but to connect the panels in parallel (all reds together.)

If you have an expensive controller which can do switchmode conversion of voltage, you can connect them in series (red to black) provided the controller can take up to 88 volt input. Then if you connect the panels in series, you will get less voltage drop from panels to battery than for parallel - but each panel only puts out 3.5 amps max.
BUT if in series and one of the panels is partially shaded you could lose power unless each panel has bypass diodes.
The slight improvement from series connection won't be worth it, unless the cable run is dozens of metres long

Thanks to everyone for your imput its as clear as mud ! only joking i think we ware on the right track cheers.