Over the past couple of days there has been much discussion about the falling costs of crystalline silicon (C-Si) PV modules as the primary factor behind the ouster of First Solar CEO Rob Gillette. I don't disagree: falling C-Si module costs prevented First Solar from gaining the market share it would have required to warrant its recent rapid expansion of production capacity. But as I was walking the floor of the Solar Power International conference last week, it occurred to me that a number of the most exciting developments on display were aimed at reducing the balance of system (BOS) costs and/or increasing the yield of PV systems. This would have been great news for First Solar given that the low efficiency of CdTe modules leads to a BOS cost penalty relative to systems built with higher efficiency C-Si modules. The problem is, a number of these innovations work with C-Si modules but not modules from First Solar (or other CdTe and CIGS manufacturers).

For example, although Enphase Energy has made the biggest splash with its micro-inverters in the residential market (where First Solar doesn't really play), Enphase is pushing its way into commercial scale installations. However, First Solar's panels don't appear on the list of compatible modules on Enphase's website (nor do most manufacturers of CdTe or CIGS modules). The voltage of these modules is too high to work with Enphase's current range of micro-inverters, preventing these manufacturers from piggybacking on Enphase's growth.

It's a similar story with ArrayPower, which introduced its sequenced inverter for commercial scale PV installations this month. The technology is currently available for C-Si modules only, and while the company could develop a product for CdTe or CIGS modules, that would require additional time, money, and effort be spent on a product for technologies that make up less than 20% of the market.

Zep Solar displayed its new solution for commercial scale rooftop installations (Zep System III) at SPI, and its mounting system is now being integrated with modules from a number of C-Si manufacturers. However, it's unclear whether the company's time-saving, grooved frame-based approach is compatible with frameless modules from the likes of First Solar.

These are a few examples of new, innovative solutions that have focused their efforts on the C-Si market first, which is a logical approach given the dominance of the technology and the similarities in manufacturing processes, form factors, and performance characteristics between C-Si modules from different manufacturers. Other vendors in this space, including SolarEdge, Tigo Energy, and SolarBridge, offer products that can function with the high voltage output of CdTe modules. If one of these companies turns out to be one of the few (if any) that succeed and become established players, that is great, but in my opinion it is way too early to pick a winner -- and being limited to only a portion of the field just makes it harder. Any winning technology is sure to expand its offering to incorporate CdTe and CIGS thin film modules, eventually, but the last thing these vendors need is to be left behind in the meantime.