In part 2 of this series I added a video that showed you how to wire photovoltaic cells together. In this post I will describe the best practice to connect the entire system together (batteries, regulator, panels).
Open space on your roof, and the number of panels you decide to install (typically 2) will determine where on your roof you can install solar panels. It is best to find the shortest wiring distance as possible from the panels to the battery bank.
8 gauge wire is the ideal size to use for your entire solar system. It will handle the fluctuating current best. Wires should be run inside flexible conduit to protect them from the sun’s UV rays. If you can run the wires through an existing vent such as the refrigerator it is better than drilling holes that could leak over time.
If installing more then one panel wire them in parallel. Solar panels do not provide consistent current, therefore a regulator is required to make sure batteries are not over charged. Panels are wired to the regulator, both positive and negative wires run into the regulator (a.k.a charge controller). A fuse or breaker should be installed on the positive wire between the regulator and the batteries. The fuse or breaker should be rated 5amps higher than the capacity of the panels, and then to the corresponding battery terminals. From the batteries the standard RV wiring is sufficient to have DC power that runs lights and some other appliances. From the batteries power runs into a inverter that powers larger appliances. Fuses or breakers should be placed between the batteries and the DC appliances and a fuse between the batteries and the inverter, if not already equipped.
Let me know if you have specific questions.
This is my third post in a series about RV electrical set-ups. Although the information is fairly basic it will help if you read the entire series.
Post #1 Deep cycle batteries
Post #2 Ratings and sizes
Batteries Parallel Wiring
There are two ways that batteries are typically wired, when there are multiple batteries being used for electrical power in your RV, that is either parallel or in a series. Parallel wiring is the most common. In this post I will describe parallel wiring. Parallel wiring does not increase the voltage, so when two 12 volt batteries are wired in this way it remains a 12 volt system. here is an example:
the effects can be seen when jump starting a car. The battery in the dead car remains 12-volts, and will still turn the starter, but only very slowly. Parallel wire a charged up 12-volt battery to the weak battery, and the dead car turns the starter at the required speed and the car starts immediately. Parallel wiring the charged battery to the weak battery did not alter the voltage – it remained a 12-volt system. The car’s system is 12-volt, and running greater voltages through that system would be destructive to it. To avoid increasing the voltage and damaging the vehicle, the batteries are simply parallel wired.
Two 12 volt batteries wired in parallel means that the positive post of each battery is connected to each other, and the negative posts are also connected together. Connecting the lead of the positive side of one battery to the load, and the lead of the other battery’s negative side to the load is the best practice. In parallel the voltage remains the same, but the amount of current available increases. Batteries connected in parallel should be the same brand, type, size, and age. Otherwise long-term capacity could be reduced. It is possible to connect more than two batteries together in parallel, but space is a major hindrance in a RV setting.
It is recommended that if you are going to wire more than two batteries together in a parallel system that they share a common positive connection, and a common negative connection. This will best allow each battery to be charged correctly. Again using the same brand, type, size, and age are important factors for the life of the batteries.
How many batteries do you use in your set-up (motor home, or travel trailer)? How long are you off the grid usually?