All Power to the Sun

Louie screws the cables into the roof in front of two of the solar panels.

We have, at long last, made the move to solar power aboard our motorhome. It’s been two years of planning and learning. But the install is over now and we're amazed at how well this is working.

Yesterday, our first day back at Honeymoon Island State Park, we unplugged from shore power. I switched on the 2400-watt inverter that’s built into our motorhome. Voila! Everything lit up and we continued as normal. The crockpot continued to cook away, the lights continued to work. The TV functioned as it usually does.

We have a handy-dandy meter built into the front of our rig now. Its task is to measure the demand on the electrical system and it also measures the solar panels on the roof and their ability to meet that demand. If they are not able to meet the demand, the meter tells me I’m in negative mode and the power I need is pulled from the six 6-volt batteries I have at the front of the motorhome. If demand is being met by the sun, the meter tells me that, too, and the power simply passes from the solar panels to the control unit, then to the batteries and back through the inverter.

I can flip through the various screens and see all kinds of information about what’s happening in the batteries. All day, I was pretty much glued to this meter to see cause and effect. When I turned on the microwave oven, for example, the power demand was very high. The microwave demanded 90 amps from the solar panels. And the panels silently met that demand because we had clear skies all day. Later in the day, I plugged in the kettle to make tea. The meter showed that I was demanding 72.5 amps from the solar panels. And they delivered.

Our system has the ability to deliver 960 watts of power at a maximum of 160 amps. It was heartening, even exciting, to see how well the sun met our needs as if by magic.

When I flipped the switch to turn on the electric water heater, however, nothing changed on the meter. That told me, immediately, that the inverter has not been wired to allow the hot water tank to be used through the inverter. We have a nifty work-around for that, however. The hot water heater can be powered by electricity or by propane gas when you are camping away from electricity. Likewise, the refrigerator does not use the inverter to make 110 volts of AC to run that. Instead, its brain knows when it is not plugged into shore power that it should switch automatically to propane for its source of power.

There are four solar panels on the roof of our coach. Each one is designed to produce 240 watts of power. All of these are tied together and then the wires come together in a combiner box at the front of our coach. This is where a pair of heavy-duty wires come through the roof and was snaked down the frame of the coach alongside the windshield. They then were routed to a compartment under the driver where they are plugged into a solar controller. This is the device that is super smart and is able to understand what’s coming in from the solar panels and then it converts all this raw energy into 12-volt power that is usable by the batteries and the inverter in the coach. Lots of wiring, to make all of this work. It was ‘way beyond my electrical knowledge or comfort zone. 

That’s where Hotwire Enterprises came in. They are located 12 miles north of us in the little Greek town of Tarpon Springs. John Gambill, a retired sailor, runs the place and he was the brain behind making this wiring work.

He subcontracted much of the electrical work out to Louie, a marine electrician, who is a master of 12-volt systems. Louie is a transplanted New Yorker who is a master craftsman. He was fastidious and careful about every connection and every wire.

Now, we will test out our six batteries in the next few weeks to see that they are up to handling the activity. We think the batteries might be original to the 10-year-old coach so it is possible we’ll have to install new ones if they don’t have the necessary holding power. In the meantime, watching my meter is more fun than watching TV!

The dash of the motorhome can be lifted to allow access to all of the fuses.