I am new to this. I have been looking at 100W panels for my RV. In comparing panels for most output, do I take the Wattage and divide it by the VMP #to get max. amp output. If this is right, HQST, NewPowa and Renogy all have different VMP #'s which give me different amp #'s. My goal is to either get 2 100W or 1 200W and a MPPT controller. I will use it on the ground so as to maximize sun. How do I compare panels to make the most amps going to battery? Thanks.
Don’t worry about the Amps; voltage is more important. The panel Operating Voltage (Vmp) must be higher than the battery voltage. Every solar panel should have a specification datasheet that provides all the voltage and current information.
If you have a 12V battery and use an MPPT solar charge controller, you shouldn’t have a problem. The charge controller will convert the voltage and increase the amps to deliver the most power.
Read this for more information - MPPT Solar Charge Controllers Explained — Clean Energy Reviews
Panels come with a rated efficiency. This is a measure of output per surface area. Like watts per square inch or the like. Higher efficiency values means more watts produced per square foot of panel. High efficiency panels are often used on homes where roof space is limited, and low efficiency (i.e. cheaper) panels are used out side if you have lots of land to put them on.
But if you’re going to be moving this panel(s) about and putting them on the ground there are other important considerations. Panels can be heavy and hard to safely move around and store when you’re not using them. Also if they are expensive they need to be protected from theft sometimes, so have to be brought inside for the night. Smaller is easier.
Also you’ll typically want to lean the panels up on something to face them into the direct sun. But if you’re not careful the wind can blow them over and destroy them. Smaller panels might be safer to deal with.
Don’t worry about volts nor amps as this has nothing to do with efficiency. Instead make sure you’re using an appropriate MPPT unit which figures out the best voltage and current instantaneous set-point to run the panels at for highest efficiency, i.e. highest output at any given moment.
When comparing solar panels for your RV solar power system, consider both wattage and VMP (Voltage at Maximum Power). Higher VMP values mean better charging efficiency. Whether you go for two 100W panels or one 200W with an MPPT controller, ensure you maximize sunlight exposure for optimal battery charging.