My first
solar system was a 50 watt panel that I set out and leaned against the truck. It had a lamp cord and alligator clips to get to the
battery, with an ammeter wired into the cord. All I wanted to run was the water pump and some
lights.
I later plugged a little cheapo volt meter into the cigarette lighter socket to monitor the battery. These things are easily found on Amazon and give a lot of information.
I no longer take a
generator, and I prefer not to run cables from the truck while camping. So, solar is proving to be a great way to keep the batteries up. Since, with me, usage will always rise to meet capacity, I now have four batteries, and a 300 watt system, soon to be a 600 watt system, as the extra panels are in the garage waiting to be installed.
As it stands now, we can watch a movie in the evening, run all of the
LED lights we want, use the built in
propane heater and
fridge, and charge two computers and two phones. If I really want to slam the system, I might make a cup of tea in the
microwave.
I recently added an electric bike. That really taxes the system, in its 300 watt configuration, but doesn't need to be charged very often, and can be done while driving such that the tow is supplying the power. And then to add insult to injury, I just added an electric coffee maker. Yikes! I have enough energy budget to have a lot of luxury items and part of the fun is having these things run off the sun.
I don't have a very sophisticated monitoring system, but I can see the amps going into the batteries, their present voltage, and get a rested voltage first thing in the morning. So I know if I'm keeping up, or not.
Remember too that a tracking system on a given set of collectors, will produce about 250% of what the same set of panels will produce if simply laid flat. So, a 100 watt suitcase system, manually adjusted during the day, can perform better than expected if simply comparing specs with a flat system. But flat systems on the roof require no setup and are always available if there is any sun.
I recently installed an MPPT controller and monitor on my system. Then I discovered that it was actually producing a little bit of power while parked under my carport! Apparently just from reflected
light off the underside of the metal roof. It's only about .4 watt, but I had no idea it would do that.