Camper Shell Solar

I always like to suggest that you do not buy peace piece meal... But instead have a plan and buy to the plan. Many times, it can be difficult to build out an effective system from mix and match parts.

• Measure the amount of power (Watts or Amps @ XX volts) and energy (Watt*Hours or Amp*Hours per day).
• Look at the results. Conservation is your friend here. In times past, a DC powered car radio could be a pretty big waste of power. New car radios may be better these days, but looking at electronics that start from battery (such as USB devices) can use less power.
• Once you have the daily energy usage, then define your battery bank size. Typically 2 days of storage plus some buffer (3rd day in case of bad weather, etc.). Note that Li Ion batteries can be near ideal for many uses... If you plan on dry camping it freezing climates, Li Ion batteries need be be kept above freezing (40 or 50F in some cases). Charging below freezing will ruin the battery and if there is a BMS (battery management system), it may shut down the battery if too cold.
• Then solar array... Enough solar to power your system (based on where/when you will be camping...). In summer of US south west, lots of sun. Up in the great white north, not much sun during winter. 
• Flexible solar panels... Many do not last even 2-5 years. Flexing can break internal connections. And sun can cause the plastic to turn brittle and fail. If you are looking for long term usage (>10-20+ years), it is hard to beat glass panels (downside, cannot conform to curved surfaces and panels can shatter pretty easily from rocks/metal tools, etc.).
• Once you have your needs... Now you can spec the parts you need for your system, and purchase to that parts list.

-Bill

Fingers typing ahead of brain...

Anyway... Just some quick example math. Say camping in Central California area. The numbers would be something like:

• 60 AH battery bank * 12 volt battery bus * 1/2 days of "no sun" * 0.80 of battery capacity = 288 WH per day 12 VDC load
• 288 Watt*Hour per day / 12 volt = 24 AH per day

Li Ion batteries are "much nicer" than Lead Acid types and don't have the min/max charging limitations that are usually seen with Lead Acid.. But some nice numbers to start with are 5% mininum solar charging (RV, sunny weather systems, etc.) tos 10-13% rate of charge for full time off grid systems...

• 60 AH * 14.4 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 56 Watt array minimum (cabin/summer usage)
• 60 AH * 14.4 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 112 Watt array off grid system.

Modesto
Average Solar Insolation figures

Measured in kWh/m2/day onto a horizontal surface (typical RV panel mounted flat to roof):

Jan	Feb	Mar	Apr	May	Jun
2.36	3.35	4.90	6.37	7.44	8.11
Jul	Aug	Sep	Oct	Nov	Dec
8.03	7.19	5.82	4.37	2.85	2.19

Say you camp March through October, or at least 4.37 hours per day of sun (Modesto). And use 288 WH per day:

• 150 Watt array * 0.75 solar DC system efficiency with Li battery) * 4.37 hours of sun per day = 492 WH per "average summer" day (October)

Not saying what is "right or wrong" for you needs--Just some modeling/math to ensure that your system meets your expectations. Refrigeration is usually a "major load" for solar power systems.

-Bill