Panel Shading Tools

Your solar provider should provide a very thorough analysis of your roof and near-by obstructions before you accept your contract. There are many websites that list tools and calculations. I found PVResources to be quite handy. [There is actually a lot of info on PVResources.]

There are some very handy tools to use, the primary one is the Solar Pathfinder. A solar installer would be able to provide a quantitative analysis of your roof and show you the areas that would be affected by shade.

Another interesting tool by Sustainable by Design that I found quite helpful was for tilted panels on flat roofs. I am sure you could use it on a sloped roof to estimate the impact of obstructions too. But I found it equally interesting to see the impact on our roof. See below! We don't have any obstructions from trees, etc. You can see with the white blocks our panels are fully illuminated, but after 4 or 5 pm the sun has gone far enough westward that it no longer strikes our SE facing panels.

Plotting Revenue Up To 14 May 2012

A quick chart to show the revenue generated from our system. The orange line is our daily loan payment amount. We don't pay daily of course, but I plot the line for illustrative purposes.

Figure 1. Daily revenue to 14 May 2012.

Here Comes the Sun!

A short blog update to provide you the latest data from my solar PV system. I have the data below for the first 2 weeks of May added to my monthly kWhr of generated power generation.

Sum - Daily kWhr	Years
Date	2010	2011	2012	Total Result
Jan		169.71	255.84	425.55
Feb		275.02	322.52	597.54
Mar		560.81	569.29	1130.10
Apr		492.89	625.74	1118.63
May		534.31	320.48	854.79
Jun		707.22		707.22
Jul		769.01		769.01
Aug	164.00	658.47		822.47
Sep	438.00	528.05		966.05
Oct	450.00	391.09		841.09
Nov	355.39	316.33		671.72
Dec	78.23	219.84		298.07
Total Result	1485.62	5622.73	2093.87	9202.21

I've mentioned in earlier posts that we need to generate approximately 375 kWhr per month to have the system pay for itself. As we've seen, December and January can be poor due to clouds and snow shading the panels. But March, April, and the first half of May have been good and more than cover the low generation from Dec-Feb. We are quite pleased that we are approaching 10,000 kWhr - likely by mid-June.