Calculators

Quick what-if numbers for one module or string, from its single-diode coefficients. Pick a module once and every calculator below uses it.

Module

Manufacturer

Model

Soiling Loss

Enter how much soiling has reduced Isc and see the impact to the rest of the curve.

Isc reduction (%)

Irradiance (W/m²)

Cell temp (°C)

Modules / string

	Clean	Soiled	Change	Change (%)

With more than one module per string, voltage and power are for the whole string. Uniform soiling only: every cell gets the same reduced light at the same cell temperature, so the effective irradiance is solved to give the Isc you entered. Patchy soiling, bird droppings and dirt along the bottom edge act like partial shading. They can trip bypass diodes and cost far more than the Isc loss suggests. The IV Analyzer can tell the two apart from a measured curve.

Off-MPP Operation

Calculate power and current loss from the inverter holding operating voltage off Vmp.

Offset

Unit

Irradiance (W/m²)

Cell temp (°C)

Modules / string

	Below Vmp	At Vmp	Above Vmp

The curve is flat near the maximum power point and drops faster above Vmp than below it, because current falls away quickly past the knee. A volt offset with more than one module per string is the string voltage, spread evenly over the modules.