Let’s assume you have followed all the steps above. You have your power inventory and know how much you need capacity for. Keep in mind that you won’t be using all your electrical appliances at once, so try and make an educated guess as to what you will use all day, and which electrical items are only used for a shorter period.
For example, your RV fridge, if running on electricity, will not run all day. It will turn on and off as needed. Similarly, if you use a toaster oven, or an electric fireplace, you usually only use those for a few hours at a time. However if your RV is like ours, the TV is on most of the day, so you need to account for that.
Once you’ve figured out your actual requirements, figure out what you need.
Let’s use the calculations we figured out earlier: We need 191 Ah over a 12 hour day:
191 Ah / 10 hours = 19.1 Amps
Since we know that Amps x Volts = Watts, so we need:
19.1 x 12 = 229 watts
Which means our single 80 watt solar panel will not generate enough power in one hour to power our needs. We will need at least 4 (4 x 80 = 240 watts) solar panels to cover our usage.
So based on our calculations we will need to have 4 80 watt solar panels to generate the 240 watts of power we need, coupled with 6 200 Ah batteries to store all our energy.
This should provide us more than enough power to keep all our devices running, whether we are plugged into shore power or not, and whether it’s a cloudy day or sunny day.