Beginner questions re. Victron 75/15 , Lifepo4 and solar setup for RV
I have a camper/trailer that I plan to set up with the following equipment and need advice on the installation. I will use it to power just led lights, water pump, exhaust fan and minimal draw from usb charger, and refrigerator control panel ( not to power the refrigerator) when camped without electric hookup.
System consists of: Victron 75/15 mppt controller, lifepo4 100ah battery w/ bms and bluetooth. I have 2 100w renogy suitcase panels that I would possibly like to wire/connect in parallel for powering the system.
The system would “top off” the battery which should be charged close to 80% from the tow vehicle when driven to camping destinations, But Also charge the battery when camped without electric hookup. Alternative plan would be to purchase a 220w suitcase panel ( for ease of setup and space) to use instead of the 2 100w suitcase panels and sell or save them for another project. In either case would it be better to use a Victron 100/20 controller or will the 75/15 be suffiecient ?
fyi: you also can use solar panels used for house roofs for a static mount because you might be loosing power in the wiring of the panels when searching for a good spot with the suitcase panels.
The two 100w suitcases each have an optimum operating voltage of 20.0, as does the 220w suitcase….the open circuit voltage of either are both @ 23.6-24v
Then the 75/100 should do fine. i would connect them in series though (and double the voltage) as the solar voltage needs to be a few volts higher than the battery voltage to start the solar charger in the morning.
The single panel would not be very useful in this case.
I have 100/30 with a 200W panel. I will typically get about 1kwh on a sunny day. If it’s cloudy and peaks will go just over 15amps. The 75/15 will be ok but at its limit most of the charge cycle in good sun. The 100/20 is far superior with a large heatsink and 48v and 36v charging options. I would go for the 100/20 they are not much more expensive or larger.
I have the same Victron/100 Ah lithium setup on my truck camper, except I have 2 panels in parallel for 225 watts of solar on my roof. So, my charge while driving comes from my solar. I only power what you plan to, nothing high powered like a microwave. Even though I have a DC-DC charger installed, but have never had to use it. I do almost all of my camping in the six months around summer in the US West. I stay primarily in forest service campgrounds and almost never in RV Parks with hookups. Based on my experience, I think you’ll be very pleased with your setup. Safe travels.
Use your panels in series when you can. The higher voltage makes the MPPT more efficient and it will extract more energy early, late and in partially cloudy conditions. The current to charger will be less with less volt drop too and you will be ok with cheaper 4sq.mm extension cables instead of 6 sq.mm more suitable for running them in parallel.
I see no reason why your setup wouldn’t also be able to supply the refrigeration load provided the fridge is 12V capable and reasonably efficient. My 40 litre Engel in my 4x4 draws 2A to 2.5A about 50% of the time and will run for 2 days on a 100Ah battery with minor extra loads for charging phones and some LED lighting.
The SmartSolar 100/20 has facility to supply up to 20A load via a low voltage battery cutoff system.
