While solar power strives to capture the sun’s inexhaustible and free energy, conventional processes of converting visible light into electricity through PV arrays have historically been expensive and complex.
Before the launch of Enphase in 2008, microinverter technology had long been a dream of the solar industry. Conceptual designs were introduced in the 1970s, and the 1980s produced prototypes crafted as smaller versions of central inverters. But like any new technology, the history of microinverters was not without its setbacks, and problems of cost, efficiency and reliability sent similar concepts sinking for the next two decades.
As a result, the industry’s growing skepticism seemingly deterred all chances of public adoption for microinverter technology. Enphase co-founders Martin Fornage and Raghu Belur understood the futility in trying to overcome doubts through another small version of central inverters. Instead, they rebuilt the inverter from the ground up by developing a new electronic topology based on a digital architecture. This allowed for a high degree of semiconductor integration, improving efficiency and reliability while reducing costs.
Microinverters are the first technology to take low voltage DC and efficiently transform it upward to AC voltages directly at the solar panel level, rather than through a string as traditional inverter technology does. Opposed to standard string inverters, microinverters eliminate the issue of a single point of failure and enable a more efficient adaptation to environmental conditions. Common issues of shading are also avoided, such that one panel shaded by falling leaves does not cause the whole system to decrease in efficiency.
To achieve power conversion efficiencies of 95 to 96%, microinverters’ digitally controlled architecture delivers rapid response time and predictive modeling capabilities at the individual module level, making each module in essence its own system. With a microinverter system, installers now have increased flexibility in system design and can leverage the integrated system intelligence to track performance remotely over the Internet.
Gaining traction as an industry standard, microinverters have surpassed traditional inverters for the first time as the number one inverter in the U.S. residential market in 2012. Demand shifts have also reached the UK and Europe, where government subsidies and regulations favor alternative energy.
The maturation of the PV market, however, is changing the role of utility companies that now face diminishing revenues and less control over energy supplies. In countries like Germany, where there is a high penetration of PV, utility companies are faced with the challenge of intermittent power produced from solar on the grid. Utilities are increasingly seeking new regulations that would adjust PV power functions and absorb the variability created by changing weather, for example. Other European utilities in large solar markets are also changing requirements for PV, and it is expected that utilities in the U.S. will increasingly follow suit.
Fortunately, the microinverter’s inherent ability to be adaptable makes it easier to address these changing requirements. Digital two-way communication allows power to be controlled autonomously by the microinverter or commanded remotely. Additional power can also be brought online within one minute of demand, all done via the Internet.
Traditional inverter-based PV systems’ static behavior leaves them inadequate to respond quickly to modified grid conditions, new utility regulations or other environmental circumstances. While it is impossible to predict what changes for the solar industry are to come, the microinverter’s adaptive nature will help PV systems better adjust to future needs.
By: Enphase Energy