Principal Solar Institute

A community for development and installation professionals in the solar industry

The Principal Solar Institute Module Ratings

The Principal Solar Institute’s scientifically designed and certified combination of tests and performance standards provide an unbiased, comprehensive rating system – the PSI PV module rating. Seven essential characteristics related to initial and long-term PV module performance are combined to create the PSI Rating:

  • Actual Tested Maximum Power vs. Advertised
  • Temperature Coefficient at Maximum Power
  • Power at Low Irradiance to Power at High Irradiance Ratio
  • Normal Operating Cell Temperature (NOCT)
  • Total Area Efficiency
  • Negative Power Tolerance
  • Annual Power Reduction

These ratings allow you to make comparisons when analyzing PV modules and help you select the optimal PV module.

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PSI Ratings – PV Solar Modules from Isofoton

Here are the PSI Ratings for modules from Isofoton, calculated based on initial performance test data. If you don’t see a solar module that you are considering, contact us and we will try to add it.

Rank Manufacturer Model Type Power
(W DC)
PSI Rating Percentile
1IsofotonISFP-270 WhitePolycrystalline2708.52*91
2IsofotonISFP-270 BlackPolycrystalline2708.48*91
3IsofotonISFP-265 WhitePolycrystalline2658.36*88
4IsofotonISFP-265 BlackPolycrystalline2658.32*87
6IsofotonISFP-260 WhitePolycrystalline2608.20*84
7IsofotonISFP-260 BlackPolycrystalline2608.17*82
10IsofotonISFP-255 WhitePolycrystalline2558.06*78
11IsofotonISF-255 BlackMonocrystalline2558.05*78
12IsofotonISFP-255 BlackPolycrystalline2558.01*76
15IsofotonISF-250 BlackMonocrystalline2507.88*70
16IsofotonISFP-250 WhitePolycrystalline2507.88*70
17IsofotonISFP-250 BlackPolycrystalline2507.85*68
19IsofotonISF-245 BlackMonocrystalline2457.73*62
20IsofotonISF-255 ClearMonocrystalline2557.66*57
23IsofotonISFP-245 BlackPolycrystalline2457.50*48
24IsofotonISF-250 ClearMonocrystalline2507.49*47
25IsofotonISFP-245 WhitePolycrystalline2457.44*44
26IsofotonISFP-240 BlackPolycrystalline2407.35*39
27IsofotonISF-245 ClearMonocrystalline2457.34*38
28IsofotonISFP-240 WhitePolycrystalline2407.30*36

* Modules denoted with an “*” use estimated values for one or more characteristics. Manufacturers can contact us to provide the missing data for these PV modules.

NOTE: PSI Ratings are based on publicly available data, and are subject to change as additional data and proprietary analyses become available for long-term performance.