Solar Help

Don is right, you have to do your math (= energy audit). There is not enough info. How low the charge drops when you have to recharge? In other words, how much amp-hours do you consume in 2 days?

If your fridge is fairly small (3 cu.ft?), then 150W should be enough on a sunny day. 50% cycle of the fridge is on the higher side. Add some block foam around the fridge if you haven't done so. On bad weather days 150W won't collect enough even for one hour of light, not to mention fridge. If you plan on longer stay like a week, and it is possible in your area to have more than 2 bad weather days in row, then you need have plan B. Like shutting the fridge off, or turning the generator on, or adding a second battery (which will give you another 2 days of reserve power).

150w on one battery is huge IMO, so mostly it should work out.

Controller size in amps should allow for 20% margin over expected amps which is the Isc of the panel with 12v PWM when pointed at the sun, with the sun up high. So 9.5a Isc needs an 11.4a controller but they come in 15a nearest.

I use the LandStar 20a from that dealer ($39) and it works very well. A 20a controller can handle 250w solar within that 20% margin if you ever got more solar such as that 150w plus a 100w

Note the unusual shape of that particular 150w. Panels come in all sorts of shapes, so watch it for your roof spaces.

Hi Mick,

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.

Here is a link to the rather special spreadsheet that N8GS has created to help size solar battery charging systems!
Solar spreadsheet by N8GS

150w should work well.

The simple EPIP20-COM controller on the same site should serve you well.

150w would about do it on sunny days.

Jim