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 Stion

Here are the PSI Ratings for modules from Stion, 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
1StionSTO-150Thin Film1507.67*58
2StionSTL-150Thin Film1507.67*58
3StionSTO-145Thin Film1457.60*54
4StionSTL-145Thin Film1457.60*54
5StionSTN-150Thin Film1507.46*45
6StionSN-150Thin Film1507.40*41
7StionSTO-140Thin Film1407.32*37
8StionSTL-140Thin Film1407.32*37
9StionSTN-145Thin Film1457.19*30
10StionSN-145Thin Film1457.14*27
11StionSTO-135Thin Film1357.08*25
12StionSTL-135Thin Film1357.08*25
13StionSTN-140Thin Film1406.97*20
14StionSN-140Thin Film1406.92*18
15StionSTO-130Thin Film1306.85*16
16StionSTL-130Thin Film1306.85*16
17StionSTL-125Thin Film1256.59*9
18StionSTO-125Thin Film1256.59*9
19StionSTN-135Thin Film1356.51*8
20StionSN-135Thin Film1356.46*7
21StionSTN-130Thin Film1306.28*5
22StionSN-130Thin Film1306.23*5
23StionSTN-125Thin Film1256.03*3
24StionSN-125Thin Film1255.99*3
25StionSTN-120Thin Film1205.78*3
26StionSN-120Thin Film1205.78*3
27StionSN-115Thin Film1155.55*2
28StionSTN-115Thin Film1155.54*2
29StionSTN-110Thin Film1105.32*2
30StionSN-110Thin Film1105.29*2

* 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.