Internal Work
PV systems require equipment other than the external modules in order to operate. This is normally installed inside the building, and can go anywhere between the modules and the incoming electrical supply, depending on space and aesthetics. We would discuss cable runs and equipment positions during a site survey.
The inverter is the "brains" of the system; this changes the D.C. current from the modules to the correct frequency of A.C. current, and transforms the voltage to 240v. The inverter monitors both the D.C. and A.C. side and protects the system by shutting it down if a fault occurs. As soon as it registers that everything is normal, it will restart by itself.
The inverter will gather data on a wide range of values including mains and PV voltage, current, operating hours and PV generated kWh. It will show the main figures on the front cover display, but the system can also be monitored in a number of different ways such as a remote display (large public one or desktop), on a local computer, or to the world via the internet.
On the 5th of August 2008 we commissioned a 5.25kWp domestic system. There are 15 x Sanyo 210W modules facing West, and 10 facing East connected to Fronius IG30 and IG20 inverters respectively. The orientations are not ideal, and there is some shading from a tree to the West, resulting in overall generation of 710kWh / kWp / year (around 80% of generation from optimum positioning). However, the system does make an interesting study because of this and is connected to the Fronius Web Portal. Follow the path; PVSystems / Home(Julian) to see the data.
Click for enlargements. All images are of Solstice Energy installations and © Solstice Energy
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