Tuesday, February 17, 2009

Solar Panels in Final Testing

Cold weather has impacted the 3rd parties who must test the solar array.

We had a very cold winter in Derby, CT this year with lots of snow and prolonged sub-freezing cold periods. This has impacted the testing and 3rd party verification of the array since the roof is accessed from the north facing slope which is in the shade most of the day with the low winter sun, causing snow or frost to linger and make it unsafe to climb. Also, the inverter and associated equipment is in a courtyard where snow sheds off a standing seam roof - see the photo to the right to see the look after a partial snow-slide. Safety is not an option in putting this solar array together, so we had to wait out mother nature.

The photo-voltaic array has been operational, and only testing has been complicated by the weather. The interconnection agreement has been signed with the utility, and it calls for 3rd party verification of equipment attaching to their infrastructure. They also have to witness a test that the system will automatically shut-off in case of a local area power failure. Although the system is fully functional, I am prohibited from even running it in parallel to the electric utility's system - so I must wait.

The utility additionally relies on local building inspectors to confirm that the work interior to the private property is done to code and they have issued a "CO" or "Close-Out" (sometimes called a Certificate of Occupancy) of the work. Derby's electrical inspector is part-time 1day per week, thus far he has only inspected the AC side of the system, and the DC side of the inverter requires access to an area where this snow was causing hazard (snow guards were planned to be installed once this roof access activity was finished). Also the building inspector must say the structural work was completed according to the structural engineer's design (I hired a 2nd structural engineer to inspect the work as the building inspector asked me to provide that verification - besides the welders license that my employee had who did the work).

There have been NUMEROUS questions about our array and when it will be throwing out electricity, how much power is generated, etc. We will have a webpage to dynamically present that data, but till then I offer the following photos taken when we briefly tested the system. During the 5min of operation at 3pm (sun getting low in the sky), the air temp was mid 50's, sunny sky clear with no clouds. Input was DC 375Volts at 178Amps. Output was AC 61.3Kw.