Main Service Panel (MSP)

The main service panel, also known as the breaker panel or electrical panel, is the central distribution hub for your home’s electrical system. It receives electricity from the utility (or your solar system) and distributes it through individual circuit breakers to the various circuits powering your lights, outlets, and appliances.

When a solar system is installed, it connects to the main service panel through a dedicated solar breaker. The panel’s total amperage rating (typically 100, 150, or 200 amps for residential homes) determines how much power can flow through it, and this is a critical factor in solar system design. The NEC’s “120% rule” limits the total amperage feeding into a panel — if your main breaker is 200 amps, the solar breaker cannot exceed 40 amps (200 × 120% = 240 amps total). If your existing panel is too small or too full to accommodate a solar connection, your installer may need to upgrade the panel or add a subpanel, which can add $1,000–$3,000 to the installation cost. A panel upgrade is one of the most common unexpected costs in solar projects.