Hi, I am currently have two solar panels on my Sprinter camper that run through a MPPT 100/20 controller to a single Leoch GTP 12110 GEL battery. I will be adding another but need advise as to whether I need to change my current controller and if another solar panel would be beneficial?
You did not mention the size of your panels, and did not mention what your daily loads are. Therefore, it's hard to answer your questions.
The best you are likely to get from a solar panel is about 70% of it's specified rating. You then need to factor in the length of time you'll get usable sun on the panel. I use no more than 6 hours. Combining this will give you the watt-hour production from the panels.
The existing controller will net you about 240 watts max, so if your panels can produce more POWER than that then yes, you should upgrade.
Next, calculate your daily WH needs based on MEASURED power consumption for each device and an estimated daily run time. For example a water pump that draws 5 amps is 60 watts but runs maybe an hour a day total so that's 60 watts * 1 / 24 = 2.5 WH. Do this for everything including any idle power. Then add up all the WH/day numbers.
