Would a technical overview help?
How solar works (the technical version)
A rooftop system is a power plant with a spec sheet. Understanding a few core terms lets you evaluate proposals, estimate production, and avoid common sizing mistakes.
It’s semiconductor physics + power electronics + grid standards.
photovoltaic basics
Photovoltaic cells produce DC power when photons excite electrons in a semiconductor junction. Cells are wired into modules (panels), and modules are wired into strings.
Inverters convert DC to grid-synchronous AC, perform maximum power point tracking (MPPT), and enforce safety standards (rapid shutdown, anti-islanding).
Key formula: Power (watts) = Voltage (V) × Current (A). Strings increase voltage; parallel strings increase current.
- kilowatt (power): instant capacity
- kilowatt-hour (energy): quantity over time
- STC: lab rating at 1000 W/m², 25°C cell temp
- PR: performance ratio (real output / ideal)
What actually reduces output
Temperature
Panels lose power as cell temperature rises. Look at the temperature coefficient (e.g., −0.3%/°C).
Shading
In string systems, a single shaded module can drag down the whole string unless mitigated by MLPE.
Clipping
If DC capacity exceeds inverter AC rating, peaks clip. That can be fine—often improves annual return on investment.
Design checklist
- Roof geometry: usable planes, setbacks, obstructions.
- Azimuth/tilt: south-ish is great; west can help with late-day time-of-use rates.
- Shading profile: trees/chimneys; morning vs afternoon matters.
- Electrical constraints: main panel, busbar limits, interconnection rules.
- Export limits: some utilities cap backfeed; storage can help.
We split topics into focused deep dives so you can skim or nerd out: