A New Twist on Inverters for Solar

And the traditional method of stringing photovoltaic panels in series has inherent inefficiencies (see The Coming Disruption in the Inverter Market).

Entrepreneurs and VC investors have turned out in full force to confront these inverter reliability and performance issues with a number of different approaches.  In the microinverter camp are start-ups like Enphase and PetraSolar, pairing discrete, self-contained inverters with each solar panel.  In another take, companies like National Semiconductor, Tigo, and SolarEdge have designed distributed MPPT DC-DC solutions which locate some of the inverter electronics at the module.

In both of these cases - energy harvest is improved and certain design constraints like panel mismatch, varying roof pitch, and shading are minimized.

Entering this fray is another player, Sustainable Energy Technologies, S.E.T., and their "Paralex" inverter.  Designed with low-voltage thin film modules in mind, the S.E.T. inverter is a parallel solution but without locating any electronics at the PV module itself.  Instead, a pre-assembled wiring harness connects the thin-film panel to a "Sunergy" inverter specifically designed to work with the low-voltages of thin film panels built from Cadmium Telluride, amorphous silicon, or CIGS.  Efficiencies are optimized for these low voltage panels.  In S.E.T.'s case "Module voltage equals system voltage equals inverter voltage."

Unlike most of the long list of players in the distributed inverter field, S.E.T. is publicly traded on the TSX Venture Exchange, a small cap bourse analogous to the London Stock Exchange's AIM listing.  For companies in Western Canada like S.E.T., the TSX Venture Exchange is a way of raising capital, absent a thriving VC community.  As testament to the value of their idea S.E.T. did raise $7.6 million from UK venture firm Doughty Hanson earlier this year.

S.E.T. is targeting Southern Europe and Greece and already has 6MW of standard inverter product in the field.  Brent Harris, cofounder and Director of Technology at S.E.T. claims they are working with First Solar's distributors in Spain and are on First Solar's approved inverter list.  He also says that one of the advantages is cost - the S.E.T. parallel inverter topology is competitive with traditional central inverters.

According to the company, their Sunergy inverter "sells for $0.40/W at a healthy margin."  

S.E.T adds yet another inverter technology to the list.