12 longform guides, each with its own live calculator using the same engine as the checker.
- Cold panel voltage: why 2 in series can hit 109V Open-circuit voltage climbs below 25°C. The formula, a live calculator, and how many panels in series is actually safe at your design low.
- Why a 6400W inverter can trip a 140A BMS Published inverter efficiency is capped at 85% here — the reason 6400W and 2400W inverters land on opposite sides of a 140A BMS limit.
- Class T vs ANL: 200A fuses, 3x the AIC A 200A ANL and a 200A Class T fuse blow at the same overload but interrupt 6,000A vs 20,000A. Why lithium banks always need the second one.
- Wire gauge: 2 rules, whichever wants it thicker wins A 15m PV run and a 1m battery cable pick different minimum gauges from ampacity vs voltage drop — ABYC E-11 math, not a rule of thumb.
- Alternator to house battery: why direct 12V wiring fails A vehicle alternator swings between roughly 12.6V and 14.8V with RPM and load - why a DC-DC charger, not a wire, has to sit in between.
- Battery bank sizing: what 2 days of autonomy actually costs Bank size is daily load times autonomy days divided by usable DoD. A real LiFePO4 vs AGM comparison shows why chemistry roughly doubles the answer.
- Why LiFePO4 batteries stop charging below 0°C Charging below freezing plates lithium onto the anode. A BMS blocks it - real batteries at -3.89°C to -30°C show why heated is not optional.
- Series vs parallel: same 400W, 4x the voltage swing 4 panels in series, parallel, or 2x2 all make 400W but differ 4x in voltage and current - computed with stringCalc() on real panel specs.
- MPPT vs PWM: a 20% efficiency gap, computed PWM clamps panel voltage to 14.4V, wasting up to 55.6% of a high-Vmp panel's output. arrayBalance() shows the real array-size cost of choosing PWM.
- Why a generic solar calculator misses a 100V overshoot A total-watts calculator approves a 730W string that this project's own voc-cold-exceeds rule flags as unsafe at Akron's design low of -24.6C.
- Why '5 peak sun hours' is wrong for half the year Minneapolis gets 5.9 peak sun hours in July and 2.8 in December. genPerKwDay() shows sizing an array for the national average of 5 fails in winter.
- Why a 50W fridge doesn't draw 50W for 24 hours A compressor fridge's 50W nameplate times 24 hours overstates real use by 4.25x. Real duty cycle, not rated watts, sets its daily Wh.
These results are for reference. Wiring must be installed by a qualified electrician. Mobile installations follow ABYC E-11; stationary ones NEC 690/706.