Micro inverters may cost more

With generous heat sinks and the right nickle blend to the aluminum alloy casing, micro inverters like Direct Grid dissipate heat well, operate from -40 to +75ºC and by applying MPPT at the panel level give me granularity second to none. Micros are coming down in price and rising in performance practically every quarter. My last installation was 603kW DC using all micro inverters, and their worst real world performance in gloomy NJ has been 8% higher than a PVSyst projection with central inverter. Our costs for micro inverters on this job were 2 cents/watt higher than central, considering reduced wire/BOS and install. Can hardly wait for summer to see if the trend continues. The fastest way to reduce cost is to integrate the circuitry directly onto the panel and do away with the separate box.

I have considered micro inverters etc when designing some installation schemes for the testing of solar modules we are planning to produce. However when I was designing the circuitry I tried out a few ideas (due to messing up my wiring network) I found that interconnecting strings and even cells in modules had a great benefit the redundant pathways during optimal performance became very useful in adverse (mismatch or shading) conditions the interconnected modules result in much lower output drops in a large installation with shading or mismatch between modules and some modelling indicates 13% better output for a 5% shading event (normal system 75% interconnected 88%) this result has made me think again about micro inverters and now plump for larger string type inverters.