Solar Help
I have an older Class B motorhome and have been thinking about solar. I can boondock now for 2 days before I have to recharge my 125ah battery. The only thing that draws power is the 12V fridge whic...
Forum Discussion
MickD wrote:
Several have said that I should get 2 panels to total the necessary watts needed.
I think they (including me too) said that you should get 2 panels with same total watts as one big panel, say up to 180W. You still can go with one 180W 12V nominal panel without getting into costly MPPT controllers (read below), but 180W panel is big and heavy.
Yes, there will be 8 brackets VS 4.
There won't be "more wire" with 2 panels. You will use the panel #10 wire to the roof junction box, and then a thicker wire into the rig. With 2 panels you run #10 wire from each panel to the same junction box. You already have those #10, they come with panels unless the panel is really cheap and small, and you will need some sort of roof junction bus anyway.
when I look at the specs for lower watt panels the IMP goes way down also the volts.
Panels up to 190-200W are - usually - 12V nominal. Vmp is around 17, give or take a little, and Imp is lower when wattage is lower. 2*90W wired in parallel will provide same Imp as one 180W.
BUT... if you look into some really big panels, like 200W or 240W, you'll notice that they have Vmp around 30. This means you can't use PWM controller anymore, and need to buy more expensive MPPT one.
