Why did the industry move from 600 volt solar arrays to 1000 volt solar arrays? The answer is simple, to reduce system costs. The value of increased system voltages is realized in infrastructure savings, reduced installation costs, and end-to-end efficiency improvements. That is the same reason that the industry is now moving from 1000 volt systems to 1500 volt systems. Central inverters have led the way, but Sungrow has just introduced a 1500V string inverter that promises a complete industry shift.
Although 1000VDC-rated BOS equipment was generally more expensive than 600VDC equipment, those costs were more than offset by the cost reductions throughout the overall system. As the volume of the higher voltage rated components and wire increased, the installed costs were reduced even further. Again, the story is repeated with the move towards 1500VDC systems. The primary reason is the 31% to 37% decrease in DC current for the same power.
Higher array voltages mean fewer strings, connections and terminations, reduced cabling, lower system losses, decreased inverter cost for a given capacity and increased energy throughput. However, a move from 1000VDC to 1500VDC is not that easy to accomplish. The availability of BOS components and solar panels that are rated for 1500VDC is still limited even after more than a year since the first 1500VDC systems were installed.