This PowerFilm solar electric...
This PowerFilm solar electric charger is rated at 12 watts. They come in arrays up to 20 watts; if you need more power, you can connect more together to get up to 20 amps. An adapter is available so the array can be plugged into a cigarette lighter to trickle-charge a drained battery.
Another way to add storage would be to add a portable battery, like the Xantrex Powerpack. This is a 60-amp/hour battery on rollers with built-in power inverter, with accessories to make it rechargeable by solar panel. It can supply both AC and DC power and is portable enough to bring power down to the beach, worksite, or campground.
However you do it, you'll want to get as many of the biggest batteries you can to store electricity for use after the sun goes down.
What's Practical?
To find out what solar upgrades can really deliver, we checked in with RV owner Mark Quasius, who shared photos of his setup for this article. He has four 120-watt Evergreen panels on his 42QRP Allegro bus coupled to an Outback MX-60 Charge Controller. For storage, he uses 12 Interstate DCS batteries, rated at 88 amp-hours apiece. He's invested about $3,000, he figures, in hardware and did his own installation. What does he get for his time and money?
"With the residential refrigerator this gives me the ability to not have to worry about running out of juice in any reasonable conditions. It also gives me the flexibility to run the genset to recharge the batteries at my convenience and removes the 'emergency' issue from the equation. It also lets me straddle any quiet time hours easily without having to be present at the coach."
His advice: "To be totally self-sufficient, you need to be a real Scrooge when it comes to using electricity, or else you will need a massive solar system. Solar power isn't for everyone. If you generally camp with hookups it's a waste of money. If you boondock frequently, having a solar panel system will extend your battery runtime and allow you to run the generator less frequently. The big advantage is that you can pick and choose when you want to run the generator set to make it more convenient for you."
Rolled up to a 3-inch diameter,...
Rolled up to a 3-inch diameter, the PowerFilm takes up very little space and is lightweight and easy to carry. Photography Courtesy of www.affordable-solar.com
Solar panels only flow electricity...
Solar panels only flow electricity when the sun shines, so batteries are a required complement to solar arrays. By adding extra deep-cycle batteries to your RV, more electricity can be harvested during the day for use at night. They can be protected from overcharging by use of a charge controller. Photography Courtesy of Mark Quasius/www.RVcruzer.com
The problem of adding battery...
The problem of adding battery storage can be solved by products such as this, a Xantrex XPower Powerpack portable battery system with built-in inverter. Plug a solar panel into this unit to store up to 60 amp-hours of electricity. It's on wheels-easier to take out into the field if need be. The Powerpack and 40-watt solar panel combo are sold as a package by Sundance Solar.
So there are limitations. Keep in mind solar panels work on light, not heat, so they do work perfectly well in the winter. As electronic devices, they actually work better in cool weather. However, in the winter, daylight hours are shorter. In snowy climates, the snow must be removed to allow light to hit the collectors.
On a cloudy day, solar cell output might be reduced by half, or down to an even lower output on a very dark day. Shadows, dirt, or leaves falling on the panels will reduce output accordingly.
The energy.gov website has a map of solar power resources. It shows that the Southwest is the best place for solar, but that solar can be used practically anywhere with diminishing returns in the Pacific Northwest and Alaska. Enhancements, such as sun tracking systems, can be used to make the most of solar radiation in those areas where average sunshine is lower.
Maintenance
The panels themselves are generally quite durable with no moving parts, but the frames around them can corrode, so they should be mounted with a slight tilt so that water drains off, rather than puddle and attack the frame. Dust tends to accumulate in the lower corners of any solar panel, which can degrade performance.
When that happens, panels can be kept clean using any non-abrasive cleaner. If output drops, it's more likely that connections at the battery or fuse holders are the culprit than degradation of a panel itself.