Basic Solar Power Electrical Equations Explained! Beginner Friendly
February 10, 2019 · 14 min · 324K views
Solar panels in series with shaded and unshaded panels shown
What this video covers
Will Prowse walks through the core electrical equations used to design and size solar power systems, covering series vs. parallel wiring, watt-hour capacity, charge controller sizing, battery C ratings, and Faradaic efficiency. Series-wiring two 6V, 100Ah batteries produces 12V at 100Ah; parallel-wiring the same pair produces 6V at 200Ah.▶ 0:00 Comparing battery capacity requires watt-hours (volts × amp-hours), not amp-hours alone — a 6V/100Ah and a 24V/25Ah battery both hold 600Wh.▶ 0:59 Solar panels wired in parallel must share the same voltage and operate independently if one is shaded; panels in series must share the same amp rating and lose all output if any panel is shaded.▶ 1:49 DC-DC converters trade voltage for amperage at constant wattage — 10A at 24V becomes 20A at 12V — which is why lower-voltage wiring requires heavier gauge wire.▶ 3:28 Solar charge controllers are rated in output amps, not input amps; a 20A controller fed 2,000W of panel at 12V must pass 166A on the output side and will burn out.▶ 5:58 Battery C ratings define maximum continuous charge and discharge current: a 1C rate on a 100Ah battery equals 100A; C/2 equals 50A.▶ 8:43 Faradaic efficiency measures round-trip storage loss — flooded lead-acid typically returns 70Wh per 100Wh stored.▶ 11:53 Series-parallel battery bank notation (e.g., 4S4P for 16 cells) determines BMS and cell-balancer compatibility.▶ 13:25
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