Pmax / Wp
Rated maximum power. Use it to total array size, not as guaranteed continuous output.
LITHVOLT ACADEMY GUIDE
Solar panels and MPPT
Panel wattage is its rated peak under standard test conditions. Real energy depends on location, orientation, temperature, shade and system losses.
Vmp / Imp
Voltage and current at maximum power. Their product is approximately Pmax.
Voc / Isc
Open-circuit voltage and short-circuit current. These set controller safety limits.
Efficiency
Power per panel area. Higher efficiency helps when roof space is limited.
Temperature coefficient
Voc rises in cold weather; power usually falls as cells get hotter.
Bifacial
Can collect rear-side light when mounting and surface reflectance allow it.
Non-negotiable design checks
Series
Adds voltage; current stays similar. Cold-corrected total Voc must remain below the MPPT absolute limit.
Parallel
Adds current; voltage stays similar. Check controller input current, connector and combiner/fuse requirements.
MPPT
Best general choice for variable solar voltage. Its output current is roughly array watts ÷ charging voltage; retain engineering headroom.
PWM
Suitable only for small, voltage-matched systems where lower harvest and limited flexibility are acceptable.
Mixed panels
Avoid mixing different Vmp/Imp in one string. If shading or orientations differ, use separate MPPT inputs/controllers.
Battery compatibility
Use the battery maker’s charge voltage, current and temperature limits; enable low-temperature charge protection for LFP.
Educational planning guidance—not a final electrical design, compliance declaration or installation instruction. Local rules and exact manufacturer data take precedence.
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