Power Optimizer
A module-level device that maximizes each panel's DC output before sending it to a central string inverter — a cost-effective middle ground between string inverters and microinverters.
Power optimizers (sold primarily by SolarEdge, which pairs them with proprietary inverters) attach to the back of each panel and perform maximum power point tracking (MPPT) at the module level. Unlike microinverters, optimizers do not convert DC to AC — they condition the DC output and pass it to a central string inverter. This eliminates the Christmas light effect while maintaining a central conversion unit.
SolarEdge systems enable panel-level monitoring and module-level shutdown (required by NEC 2017+ rapid shutdown codes in many jurisdictions). The DC voltage on the roof can be set to a safe level during emergencies — a safety advantage over traditional string inverters.
Optimizers cost less than microinverters (approximately $50–$100/panel premium over string inverters alone) while delivering most of the shading mitigation benefit. The central SolarEdge inverter is still a single point of failure (if it fails, the whole system stops) and requires replacement in 10–15 years. Power optimizer systems are the most popular choice for residential installations with partial shading.
Real-World Example
The SolarEdge monitoring portal showed the optimizer on panel 4 reporting 22% lower current than adjacent panels — the installer found a cracked junction box, replaced it under warranty, and production immediately normalized.