Tesla, which is in the process of taking over Solar Cityin a $2.2bn deal, is using heterogeneous photovoltaic cells from Panasonic and adding its own tempered glass cover (below) to make the cells more rugged and attractive as roof tiles. The cells combine crystalline and amorphous silicon and provide an efficiency of 19%. The additional glass layer reduces the efficiency of the cell by only 2%, says Tesla.
The tiles include an option of a heater to clear snow so that the cells can still be used in winter and will be paired with the second generation of Tesla’s Powerpack. This uses lithium ion battery cells developed and manufactured by Panasonic. The Powerpack 2 combines two of Panasonic’s 14kWh battery packs with an integrated inverter designed and built by Tesla at its battery gigafactory in Nevada, US.
This significantly simplifies the installation process of the Powerpack system by integrating a number of previously independent components into the inverter itself.
The approach contrasts with the approach taken by European manufacturer Heliatek with flexible solar cells on a roll that can be installed on walls or roofs and a European project to develop 'living bricks'taht generate power from buildings.
Analysts predict the move to more solar production will drive down the cost of lithium ion packs. Bloomberg New Energy predicts the cost of a home battery pack will fall to $262/kWh by 2020.