Helpful Tips and Stuff We’ve Learned Living Off Grid
I’d like to tell you about what I call the poor man’s solar tracker. I regularly get calls asking about the use of solar trackers. I have always said that I think that a solar tracker has its place, but for most installs I feel it does not make sense. The cost of the tracker and the continuing maintenance costs are far outweighed by the ease of just adding extra modules to the array. This in effect equals the added efficiency of the tracker for the same costs and without the maintenance.
So when does a tracker make sense? When you have a very small footprint of solar isolation available. Let’s say you have a small back yard with just one corner in the sun and your roof is not available. A tracker can work great to harvest the most sun in a limited space.
I have recently started suggesting the poor man’s tracker to my clients. In the last few years we have had the opportunity to install pole mount solar arrays that consisted of two pole mounts of equal size arrays. On a hunch I started to experiment with taking the two pole mounts, dropping the tilt to 20 degrees and facing one of them to the southwest and one to the southeast during the summer months. My suspicions where confirmed through testing that the resultant losses due to not being faced true south were very small, less than 10%.
Remember that in the summer when we have an abundance of power, and when the batteries are charged up, the solar array can only feed to the loads and all other available power is lost. But with our array skewed to the east and west, the overall result, was a dramatic increase in our solar window. What this means is that the southeast facing pole mount would pick up the morning sun much earlier and start recharging the battery bank early in the day and the southwest facing pole mount allows the solar array to power loads late into the afternoon saving the battery bank for as long as possible.
As far as a winter setting, we have found that a south-facing array at 40-50 degrees is still the best option. Changing the pole tops twice a year on the winter and summer solstice is easy and just takes a few minutes to do. This type of setup is only advantageous to an off grid installation and a grid tie system would not benefit from this.