We have installed an 8.4 kWp PVT array comprising 48 PowerTherm panels on this 6-storey roof at Warwick University. The array is mounted on purpose-built, ballasted aluminium frames. The base and ballast are covered by a sedum roof.
Thermally the panels are arranged into 8 interconnected sub-arrays with the flow of heat through the array controlled by balancing valves to prevent local overheating within any single module. The array is connected via a plate heat exchanger and a store charging circuit to a 5000 litre accumulator tank located in the plant room, also connected to the university’s district heating network. A BacNet interface connects the controller to the Building Management System (BMS).
To mitigate the impact on the output of the array by shading from nearby objects at low angles of solar inclination the panels have been electrically subdivided into 12 separate strings. These are connected to 3 StecaGrid 2010+ inverters (master/slave) each of which can support 4 separate maximum power point trackers (MPPT). Each string is linked to a separate MPPT ensuring that if that string is partially shaded it does not drag down the performance of the other strings.