I often get asked when consulting, how do I account for panels not facing north, a low pitch roof or surrounding tree lines for example. For some, this can be done by providing an ‘estimated’ system yield taken from predetermined values.
That’s not very good design and definitely not good enough for me. Designers can get their hands on different technology and applications for this process. For me, I use a device called a Suneye produced by Solmetric. Put simply, it is a 180 degree fish-eye lens with an inbuilt GPS. Solmetric have produced a very nice software platform that will project annual efficiency outcomes based on location, roof pitch, azimuth angle and also accommodate for any shade paths specific to the images taken.
This result forms but one of at least (six) de-rating factors considered to accurately project system performance. Our remaining de-rating factors are taken from electrical standards which may include, but not limited to; Temperature, Voltage Drop, Dirt Coverage etc.
System performance figures can include average daily yield and an expected return on investment. Ask your consultant what de-rating factors they have accommodated for and if you’re not confident with the answer, I wouldn’t be either.
We hope this has helped in your educational journey toward your solar investment. If you would like further advice, feel free to send in your questions.