TSRF, What is Total Solar Resource Fraction?

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    What is TSRF?

    TSRF, or Total Solar Resource Fraction, is the amount of sunlight the measured area will receive over the year. In more scientific terms, it is the ratio of insolation available accounting for both shading and Tilt and Orientation Factor (TOF), compared to the total insolation available at a given location at the optimum tilt and orientation and with no shading.

    A 100% TSRF is very rare due to trees and other shading factors, but it represents an area that will get all possible sunlight. 

    TSRF Example

    Minimal Qualifications (Oregon Only)

    To qualify for all available solar incentives, you will need a total solar resource fraction greater than or equal to 75% with a Physical Assessment and 80% for a Remote Assessment (see below for the differences). For most projects, we initially do a remote assessment to qualify the customer’s total solar resource fraction.

    On-Site TSRF Analysis

    This is our most common type of assessment. We perform physical assessments when we want more detail about your roof structure. These also allow the customer to discuss how they would like the solar panels and wiring to be placed. On average, the physical assessment will take no more than 30 minutes. Equal or great than 75% is the minimum TSRF qualification.

    Remote TSRF Analysis

    We use remote assessment software to analyze your project site using the latest satellite imagery, aerial 3D height scans (LiDAR), and up-to-date incentive information as well as current utility rates. The remote software we use is Energy Trust of Oregon approved because of its high level of accuracy. Equal or great than 80% is the minimum TSRF qualification.

    Get A Free Roof Analysis

    Because calculating angles, TOF, and determining the optimal location for the solar electric system requires professional know-how and equipment we recommend signing up for a free solar analysis. We will provide you with the information you are looking for to make the right decision.

    home representing the tsrf total solar resource fraction


    Adam Walters

    Adam Walters

    Adam has over 8 years of experience working directly with Portland-area solar installers and supporting companies. Over his years, he has worn many hats and gained a holistic understanding of local PNW solar markets.

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