Solar Panels- Pro vs Cons

[john_harris]

My Wife and I do a fair amount of boondocking and manage electrical consumption and charging with the 8000 watt Onan Genset without issue.

While several posts and articles in FMC mag talk about solar panels, I have not really seen a definitive conversation about how much bang for the buck you might get by installing them. While I am not looking to run Microwave/convention oven or ac off them, I would want to be able to watch TV, run a few lights and cell phone charges and even the DC side of furnace without needing to turn on generator.

Right now we can manage to do that most of the day while maintaining batteries above 12v. If solar panels would only keep me from running generator for 45 min or so to bring back to absorb charge, not sure cost is justified. Come dinner time, we would be turning on genset anyway to run MW so charging anyway. When stored, RV is in garage and plugged into 50 amp service so solar no real help with maintaining batteries when not in use.

Any pros and cons would be appreciated

[wolfe10]

John,

No simple equation. It sounds like you have a pretty good grasp of the variables:

How many days a year do you dry camp?

In full sun, part shade, "in the thees"?

Cost of panels and MPPT controller.

Cost of installation.

Added weight to roof.

Likely life expectancy of solar components.

Cost to run generator enough hours to reach break even point within coach ownership period.

Another option would be to upgrade your battery bank to either more capacity (wet cell or gel) or go to AGM's which will accept a higher charge rate (assuming your inverter/charger can supply a higher rate than current battery bank can accommodate.

No right or wrong answers here.

[desertdeals69]

I have 600 watts solar with a 40 amp 3 stage MPPT controller and 6 AGM golf cart batteries. Cost for the solar system was about $900. We have a fairly high usage with 40 inch TV, Directv and equipment and bedroom TV and equipment and occasional use of the microwave or toaster. With moderate sun light the batteries are maintained. If you park under a parking lot light with the new LED bulbs it will charge at 6 amps all night!

[evolvingpowercat]

Solar panels cost about $ 1.60 per watt on Amazon.com with shipping. Add about $ 10 per panel for Z brackets and cabling. Another $ 30 for a charge controller, very important to make sure you don't over charge batteries and lose the water out of them. If your coach already has an inverter that drives your entertainment system 120 volt AC items you would be all set.

Change all the lights you will use more than a few minutes per day while boondocking to LED.

If you have a nearly new LED TV with what is called "LED backlighting", these are VERY efficient and will use under 2 Amp-hour of battery per hour of use. Older TV with "light bulb" backlighting will use 10 Amp-hour of battery per hour of use OR MORE depending on size. So you MAY want to upgrade your TV and use less solar panels.

Satelite TV Receivers are power pigs and also draw 10 Amp-hour OR more depending on if they have DVR recording or not.

The furnace 12 volt blower draws about 10 Amp-hour while running.

For each 80 watt solar panel you install, you can expect to do between 25 and 50 amp-hours of battery charge per day depending on sun/shade and amount of sunlight on a given day. Panels will put out some charge even when its cloudy.

It sounds like you have a large coach so chances are you have 4: 6 volt batteries or 2: 12 volt batteries with 200 Amp-hour of storage. Lead acid batteries last longest if they are not discharged below 50% so this gives you 100 Amp-hours of use on the batteries when you are drawing more than the solar panels are putting out.

Think you might want to start with 2: 80 watt solar panels.

RAS

Manhattan, Kansas

2008 Itasca Cambria 29H - with 1: 80 watt solar panel