Solar charging in a shady spot?

By Bob Difley

Boondocking in the national and state forests in summer and using solar power to provide your electricity presents different challenges than found when snowbirding in the southwestern deserts.

In the desert, because most campsites are open to the sky, you get charging from your panels from the first glint of sun over the morning horizon until it has passed out of view in the western sky. However, since the angle of the sun is lower, you will not receive the charging power your panels are capable of unless you tilt your panels toward the sun’s trajectory across the sky – getting as close as 90 degrees to the sun as possible. Position your RV horizontal to the sun’s movement, and verify that the elevated panels – or other rooftop equipment – do not shade the silicon part of the panel.

Since winter days are shorter, your total charging time will be shorter, and your batteries may not have sufficient time to become fully recharged. Therefore, you may have to schedule more electricity-using hours (meals, showering, computer use) during daylight, so as not to deplete too much from your batteries overnight.

When you move from the desert to a pine-shaded campsite, however, your challenges change. Since the sun during the summer months passes more directly overhead, your panels do not have to be elevated to take full advantage of the sun’s rays throughout the day.

Days are longer so you have many more charging hours every day than in the desert, and since the number of nighttime dark hours roughly equals the eight hours of sleep needed, most electricity-using can be accomplished while the panels are charging if you coordinate your sleeping and rising times with the sun’s rise and set.

But now comes the hard part. Since you are camping in a forest, you will undoubtedly have periods of the day when the sun is blocked from reaching your panels by the magnificent (and tall) trees surrounding your campsite. Short of camping out in the middle of a meadow (which can be nice) you will have to guess where to park to get as many hours of sunlight as possible reaching your panels.

Try to avoid any part of the panel being shaded since that reduces the amount of amps that pass into your batteries. Then watch the sun as it moves across the sky and watch for when your panels are blocked. A small move or repositioning may gain more sunlight. Unless the surrounding trees are very tall or very close to your campsite, you should be able to get enough midday sun hours from overhead to give your system some good strong charging.

The remaining consideration in both desert and forest is the number of overcast or rainy days, which will produce reduced battery charging. It is therefore a good idea to oversize your system slightly to account for all the variables.

You can find Bob Difley’s RVing e-books on Amazon Kindle.

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4 Thoughts to “Solar charging in a shady spot?”

  1. Bob

    A great app for your phone that will tell you the shade pattern where you’re standing/camping is “Sun Surveyor”. It has a live view option that uses the camera overlaid with the route of the sun during the day. Just point the camera along the overlaid route and see what trees etc. will be in the path of the sun throughout the day. We’ve used it to get morning sun and afternoon shade for years.

  2. Tommy Molnar

    The other option is to add more panels. Not cheap, but the more panels you have, the more power you get, even on rainy days. We recently upgraded from 375 watts to 700 watts. Now, no matter what (unless I have to shovel snow off the panels), we get a full charge every day. Plus, we really don’t use all that much power anyway so this is relatively easy to achieve.

  3. Scott

    In any but the shortest term, it doesn’t matter whether you do electrically intensive activities while the panels are producing power. If you use more amp hours of power in any given LONGER time period (24 hours, say, or a week) than you’re producing, your batteries will lose ground. If you don’t, they won’t. When you happen to impose a load on them doesn’t change that calculus.

  4. Bill.

    My portable panels work great for both scenarios, since I can move them with the sun and maintain as much output power as possible.

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