Spotlight on Accuracy: Correcting a Mathematical Error in the ILSFA Approved Vendor Manual

At SOL POWER MIDWEST, we take pride in our accuracy, transparency, and dedication to the communities we serve. As Illinois’ sole ILSFA Approved Vendor for the Bright Neighborhoods Initiative, serving Chicago’s West Side, our mission is to deliver affordable solar energy solutions to more than 1,500 income-eligible residents in Austin, Humboldt Park, East Garfield Park, West Garfield Park, North Lawndale, and South Lawndale.

This commitment to excellence means ensuring every detail is correct—even seemingly minor errors. Recently, while developing our financial models, we identified a mathematical error in the ILSFA Approved Vendor Manual (Version 7.0) for the 2024-2025 Program Year. This error, found on page 56, relates to the calculation of the Total Energy Value and warrants clarification.

---

The Error

The manual presents the following calculation:
Total Energy Value: 43,459 kWh × $0.1248 = $6,109.47

However, this is mathematically incorrect. The correct calculation should be:
43,459 kWh × $0.1248 = $5,423.68

The discrepancy arises because the dollar value provided in the manual, $6,109.47, aligns with the Year-15 Cumulative Avoided LEU Cost with Escalation. To achieve this value, the calculation must use the 15th-year PPA rate of $0.1580, rather than the first-year rate of $0.1248.

Here’s the corrected calculation:
43,459 kWh × $0.1580 = $6,109.47

---

How $0.1580 Is Derived

The rate of $0.1580 is derived by applying a 1.7% annual escalation rate to the first-year PPA start rate of $0.1248 over 15 years.

This adjusted rate reflects the compounded annual escalation over 15 years and should be used to calculate the Total Energy Value for Year 15.

---

Why This Matters

This error is more than a simple oversight. It highlights a significant issue with accuracy in program documentation, which can create confusion for stakeholders, including clients and financial partners.

Additionally, the ILSFA energy calculator, previously available for verifying these figures, is no longer accessible. Energy savings calculations are now embedded within the disclosure forms and are automatically generated. While these forms are designed for precision, the lack of transparency makes independent verification challenging.

For SOL POWER MIDWEST, ensuring accurate financial modeling is critical to maintaining trust with our clients and delivering the promised benefits of solar energy. The communities we serve deserve clarity, and errors like this, if left unaddressed, can erode confidence in the program’s administration.

---

Moving Forward

Our intention in highlighting this issue is not to assign blame but to advocate for improvement. By addressing and resolving such errors, we can foster trust and collaboration, ensuring the program’s success for all stakeholders.

We encourage program administrators to review the embedded calculation tools in the disclosure forms to verify their accuracy. For our part, SOL POWER MIDWEST remains committed to scrutinizing all program details, advocating for transparency, and delivering high-quality solar solutions to the communities that need them most.

This isn’t just about numbers—it’s about accountability, trust, and delivering on the promise of clean, affordable energy for all.