Scotty is asking the right questions, saying you get a 20% to 30% increase is a broad generalization. You need to look a little deeper if you want to calculate ROI on a tilt-able set up. Which direction the panels are facing has a big impact on the irradiance numbers, also you will find the largest increases on seasons that are already low.
The table above is for the Beaverton Oregon area, I ran the calculators at
http://www.solarelectricityhandbook.com/index.html. I ran them for facing south, east and west. I ran them with the panels Flat, Optimal for the Year, and adjusted throughout the year. Summer and Winter. For Beaverton the optimal angle for the year is 44°, while the winter is 29° and the summer is 59°. My spreadsheet basically use the flat setting as its baseline, all of the % numbers are based off of that, Positive percentages mean that the flat setting is higher while negative (red ) will mean that the angle setting is higher. The chart is in monthly columns with the last column being the average of all months.
The first data point is south, and when we compare the Optimal setting to flat on average it is 8.14% higher. this data point would lead you to believe that angling would be worth it. A careful look at the prime camping months (May through August) show that the flat setting is still higher. Admittedly the Jan and Dec numbers are way distorted to the angled side, but while the percentage is high the actual change is much lower do to the lower irradiance for the season.
On the second set we look at a row where the panels were adjusted for the time of year, here again we see that the average number is 13.58% higher, and the flat setting only gets higher numbers in May and July. This is better then the optimal setting, but it will cause you to need adjustable settings on your tilt design.The remaining rows are for the winter setting and a summer setting, again follow trends that one would expect.
Based on this data I may convince myself, that an adjustable set up would be worth it. But now let's look at the data when we are pointed west instead of south. here the average numbers for optimal are negative, or worse then the flat panel setting. In fact now March through September get better numbers at the flat setting then at optimal year round. Even the adjusted through the year are not as good as the flat settings.
Similar data is available for a east setting, so now with a little more data we see, not only do we have to maximize the angle of the panels we also need to make sure that they are pointed in the most optimal direction for us to see a ROI on our adjustable system. Can it be done, sure, but you might be better spending the money on a extra panel or an extra potable one for the winter months.I have also run numbers for San Diego, which shows a similar trend but the data is even better a flat panel position then in Beaverton.
Hope this helps
Greg
Linear Mode
