Balance of System (BOS)
All solar system components beyond the panels themselves: inverter, racking, wiring, monitoring, electrical panel upgrades, and installation labor.
Why It Matters
BOS accounts for 50-60% of total system cost. When comparing quotes, differences in BOS components (inverter brand, racking quality, monitoring) explain much of the price variation.
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Cost Per Watt
The standard metric for comparing solar installation prices, calculated by dividing total system cost by its DC wattage. US average is $2.50-$3.50/W before incentives (2024).
Soft Costs
Non-hardware expenses in a solar installation: permitting, inspection, interconnection fees, customer acquisition, labor, overhead, and profit margin. Soft costs are ~65% of US residential solar prices.
Inverter
A device that converts direct current (DC) electricity from solar panels into alternating current (AC) electricity used by your home.