Balance of System (BOS)

Balance of System (BOS) refers to all components of a solar energy system except the solar panels themselves. This includes the inverter, racking and mounting hardware, wiring, conduit, combiner boxes, disconnect switches, monitoring equipment, and the electrical connections to your home’s breaker panel and utility meter.

BOS components typically account for 40–60% of the total installed cost of a residential solar system. While solar panels get most of the attention, the quality and proper installation of BOS components are equally critical to system performance, safety, and longevity. A well-designed BOS ensures efficient power conversion, code-compliant wiring, reliable weather protection, and safe operation for decades. When comparing solar quotes, it’s important to look beyond just the panel brand — the inverter type, racking quality, and wire gauge all affect long-term system performance and maintenance costs.