Solar Panels on a Berkshire

[Anders]

Just this week we added the Solar Elite package to our 5th wheel. Will be spending the winter on the beach in Baja, MX. I can run pretty well everything except the AC.

[Cornelius]

I initially installed two 140 watt panels on the roof of my Georgetown, with space for two additional panels to be added later. The two panels worked well, but since they are flat on the roof and often in hot weather, the electrical output was sufficient to charge the batteries, but not provide any extra power for daytime needs. A year later I added two 120 watt panels. The manufacturer had changed the dimensions of the 140 watt model, so they were no longer available to fit.

Each solar panel is secured to the roof with 8 "Z" brackets. I used #10 stainless steel screws as they have a large threaded "bite" for attaching to the plywood underneath the fiberglass roof. Use a gob of Dicor under each bracket where the screw goes into the roof, and additional Dicor over each bracket once it is installed. It is important that the solar panels are not shaded by a roof vent, TV antenna, air conditioner, etc. Even just a small amount of shade on one individual solar cell can shut down the entire panel.

10 gauge UV resistant photovoltaic wire is used for connecting the panels to a roof junction box. If you install 3 or more panels in parallel, each panel needs to be individually fused at the junction box. From the junction box use 4 or 6 gauge wire down to the controller and then to the batteries to minimize voltage drop. Since the 4 gauge wire I used was not UV resistant, I installed it in conduit where it is on the roof.

The 45 amp controller was sized to allow for the additional panels to be added. It is installed in a basement compartment close to the batteries (but never in the same compartment as the batteries). In addition to the controller, there is a disconnect box to isolate the positive lines to the controller from both the solar panels and the batteries if servicing is needed. I also installed a small 300 watt sine wave inverter that is wired to new outlets to supply power for small loads such as the bedroom LCD TV or a laptop computer. Fuses are installed for both the inverter and solar controller as close as possible to the battery terminals for safety.

[5456Mich]

Cornelius, Looks like a nice set up. How did you get the wires from the roof down into the basement ?

[Cornelius]

Originally Posted by 5456Mich

Cornelius, Looks like a nice set up. How did you get the wires from the roof down into the basement ?

I used a hole in the roof that was previously made by "professionals" who installed a Winegard satellite dish for the previous owner. These guys drilled the hole at the edge of the roof where water collects, and caused a small leak. They also managed to hit a roof truss and the 12 volt line for the ceiling fan and air conditioner relay box...

When I removed the satellite dish (which I never used), and fixed the mistakes made by the installers, I installed a weatherproof electrical box over the roof hole with Dicor. No more leaks. Because I wanted to use the existing hole, I had to use a second junction box and conduit to protect the 4 gauge wire from the sun as it was about two feet from the solar panels.

Normally, one weatherproof box to connect the 10 gauge solar panel wires to the heavier 4 gauge wire would suffice. I would have made a hole near the center of the roof into the TV cabinet. From there the 4 gauge wires run into the basement compartment adjacent to the battery area.

Since you have a residential refrigerator, there is no refrigerator vent for you to utilize for running the wires, as is commonly done. My refrigerator is in a slideout, so I don't have a roof vent there either. Sometimes a holding tank roof vent can be used for running the solar wires down to the basement. If you decide to drill a hole in the roof for the solar wires, check, double check, and check again before drilling.

Running the 4 gauge wires from the roof, through the TV cabinet, and to the basement, along with making the plywood board with the solar controller, disconnect, and inverter were the most time consuming parts of the job. The solar panels actually installed on the roof fairly easily.