Tuesday, October 11, 2011

Field Trip: LARGE Residential Solar Installation
Speaker:   Steve Steffel, P.E.
                 Mgr, Distributed Energy Resources and Analytics, Pepco Holdings, Inc
                 IEEE Delaware Bay Member


Fortunately, we had plenty of daylight left at 6:30 for most to walk around Steve's solar panel installation. The installation size was 19.4 kw, which used 90 panels in a 15 x 6 array. The panels could be adjusted in elevation, and Steve is experimenting in how to do the adjustments as the sun changes it's position with season. The installation was built by Steve, his son, and help from all available relatives. 

Steve used a microinverter per panel. This was a little more expensive than using one or two large inverters, but more data and individual adjustments could be made with the smaller inverters. 

Steve explained that the relationship between his solar panels and the power grid was much more complicated than one might suspect. The main problem is that the grid must protect itself from sudden swings in both load and feed from Steve's residence which could cause voltage swings. Some of the potential problems are sudden shutdowns of the solar feed to the grid due to overvoltage protection, then sudden resumption of the feed when the problem is fixed and an erratic sun exposure due to clouds. 

Steve's Presentation (pdf  2,332 KB)

Steve's Website: