An existing motel in Hobsonville constructed a new Pool House, and utilising Solar was part of the design brief for the architect from the outset, so the roof was perfectly pitched and orientated for Solar generation.
In this case a 4.8kWp rooftop array with Micro Inverters was installed, but as part of the overall scope we also provided a complementary heat pump system for the pool. This system consisted of 15 x 320W Trina SplitMax Monocrystalline modules, with Enphase IQ7 3ph Micro Inverters for each panel; and 2 x 21kW heat pump pool heaters.
Micro inverters are an alternative to a conventional single string inverter. Instead of a single central inverter, a micro inverter is fitted to the underside of each panel that are supported by a central controller called an ‘Envoy’ that also collects performance data for monitoring. This technology is advantageous in situations where there is unavoidable shading at times during the day because in a typical system with a central inverter, if one panel experiences shading it lowers the output of all the panels in that string to that of the lowest performing module. With micro inverters, only the shaded panel output is affected.
This can be more costly than a basic string inverter system but that cost is usually far outweighed by the value of the loss of production over the lifetime of the system. In this context there was no doubt that all generated energy would be used within the complex which maximises the financial benefit from the Solar array so it made sense to invest in a more efficient system.
This efficiency was also complemented by the split cell technology of the Trina modules. They look very attractive and unobtrusive on a dark roof due to the black cells, backing sheet and framing, but SplitMax modules also have efficiency benefits in that the module is split into two circuits, so that if the top half of the module is shaded, the bottom half is unaffected. This technology is becoming more common and standardised in the industry.
