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Solar Panels – Considerations.
If you are into free camping then you appreciate how important it is to maintain a good reserve of battery power. One way to do this is with solar photovoltaic panels. It is worth your while to consider this energy alternative for extending you free camping stay. However, in order to make an educated decision there are several things you need to understand and consider before dipping into your pocket. Solar panels for camping can be permanently mounted assemblies or more portable folding systems that you can adjust to follow the sun. What ever you buy, here are a few points to consider.
When you see a solar panel rated at 100 watts output, it will only produce that output under “Standard Operating Conditions”, and the best place to find out what that means is from the manufacturer. Question how they arrive at that figure – you may be surprised.
The wattage rating is just that. It is based on the output voltage and current of the panel NOT the usable power after regulation. For example, lets say you see a 100 watt panel you want to purchase for camping purposes. You might tend to think that the panel will provide you with 8.33 Amps of current at 12 volts. Not so. Most panels produce in excess of 18 volts with their maximum current being delivered at around 16 volts. So for a quoted 100 watts you now have only 16 volts multiplied by 6.25 amps to give you the magic 100 watts. Now if we assume no losses at the regulator, our output watts will be 12 multiplied by 6.25, or 75 watts. If we take regulator losses into account this will likely reduce to 70 watts, or less if you are not directly under the full sun.
It is easy to assume that if you place a panel out in the sun then it will do its best to deliver peak energy. As we all know the sun drops behind cloud cover and so the peak sun hours drop appreciably over a normal day. You need to account for the region you will be camping in (or reside in) and get a good handle on averaged peak sun hours. This will determine your actual watt hours over a day.
Most solar panels do not work in full shade, and in partial shade the output differs for different manufacturers. Some lose just about all output if only a small portion of the panel is shaded. For maximum output you need to ensure your panel is positioned to capture all sunlight falling on the area. You could employ a sun tracking device but they are complex and therefor expensive. Best to add a safety margin to your calculations of around 20%. In other words, if you want 100 watts go for the 120 watt panel.
Most solar panels work best at lower temperatures. So, if you camp on the top of a mountain on the equator you are going to get the best output at noon. Some sources state that panels lose 5% output for each 10 degrees Celsius rise over about 25 degrees. On a hot day then your rated 100 watt output could fall to 50-60 watts.
This may have appeared to paint a somewhat negative picture on solar but the focus is on being aware of the facts. I am convinced that solar is a viable option for extending dry camping stays when coupled with a suitable battery and charging system. My choice is to go for a portable folding style that gives you the option of camping in the shade but making the most of the sun for your power needs. Just be aware of the characteristics; do your research; and purchase wisely.
If you want to know more about dual battery systems try this post.
Filed under: Camp Site Tips, General Tips, Smart Ideas
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