Today I conducted a little test to compare the performance of two low cost solar site assessment tools. I consider low cost to be anything under $1,000. These tools provide infomation about the amount of available sunlight that falls on a surface. They do this by examining the landscape features in the area that provide shade at different parts of the day such as buildings and trees. These tools provide a percentage of available solar radiation you can expect to receive. This can then be combined with weather data and solar panel information to perform preliminary energy calculations using energy modelling software. This site assessment information is supplied for each month however for the purpose of this test I am only going to compare the total annual values.
The two tools I compared are:
1) Solar Pathfinder (http://www.solarpathfinder.com) $299 + $199 software
Solar pathfinder image. The black areas inside the ring mark the obstructions in the surrounding area. This image is traced using computer software.
2) Solmetric iPV iPhone application (http://www.solmetric.com/solmetricipv.html) $29.99
The Solmetric app lets you trace the obstructions directly with the iphone.
The calculations for the percentage of available sunlight were as follows:
Solar Pathfinder: 84%
Solmetric iPV: 86%
Both of these tools require tracing so they have a element of human error involved. When using the pathfinder you take a picture of the equipment and trace it using the computer software. When using the Solmetric app you trace the horizon directly with the iphone. Given the close proximity of the results I don’t really feel as though one is any better than the other from a performance standpoint. When you consider the price the Solmetric iPV iPhone application is the clear winner, but only if you already own an iPhone.
Solmetric also makes professional site assessment tools in the $2,000 price range that do not require any manual tracing and are remarkably accurate.