New on FinoLib · Volume III: Finance Encyclopedia
I have just published a new article on FinoLib, my free finance education library: Solar Project Finance: 48E vs 45Y Tax Credits Explained. It is part of Volume III: Finance Encyclopedia. Below is a summary of the topic in plain, expert language, so you can follow the idea even before you open the full article.
The idea in plain words
This case follows the financing of a US solar project in 2026. The return is decided mainly by federal energy tax rules: the choice between the Section 48E investment credit and the Section 45Y production credit, 100% bonus depreciation, and whether construction began in time under the July 2025 OBBBA deadlines. In this case’s numbers, the production credit wins above about a 17% capacity factor, and missing the placed-in-service deadline would swing the project’s value by about $86 million.
Key points
■The ITC is 30% of qualifying cost with prevailing wage and apprenticeship met; the 2026 PTC is 3.1 cents per kWh for 10 years.
■Claiming the ITC cuts the depreciable basis by half the credit, which costs $7.9 million of year-one tax savings on a $250 million plant.
■Solar whose construction begins after July 4, 2026, earns no credit unless placed in service by December 31, 2027; beginning construction now requires physical work.
■Credits sell for about 93 to 95 cents per dollar; depreciation cannot be sold, which keeps tax equity alive.
A closer look
The situation: In October 2026 a consortium is financing a 200 MW (AC) solar plant in the US that will sell all its output for 20 years at $55 per megawatt-hour (MWh) to a state utility under a power purchase agreement. Physical work of a significant nature began on site in May 2026. The project figures are illustrative assumptions; the tax rules are the actual US federal rules as of October 2026. The decision: claim the investment tax credit (ITC) or the production tax credit (PTC) — a facility takes one, not both — and finance what remains.
Financing what remains. Lenders size project debt to CFADS (Part 2.5: Project Finance — The Infrastructure Financing Model). At a 1.35× debt service coverage ratio, the maximum debt service is $19.09m ÷ 1.35 = $14.14 million a year; over 18 years at 6.5%, that supports $14.14m × [1 − 1.065^−18] ÷ 0.065 = $14.14m × 10.43 = $147.5 million, or 59% of cost, leaving $102.5 million for equity and tax capital. An 18-year amortizing loan backed by a contracted, utility-paid revenue stream suits life insurers with long liabilities — exactly the buyer Case One showed wanting duration.
A worked example
Worked Example — Compare the Scenarios: ITC or PTC by Site Quality
Present values at an 8% discount rate, with credits sold at the late-2025 prices above. ITC side, received after one year: $75m × 0.931 = $69.83m, ÷ 1.08 = $64.65m, plus depreciation $44.63m ÷ 1.08 = $41.32m, total $105.97m whatever the site. PTC side: annual credit × 0.94 × 6.7101 (the 10-year annuity factor at 8%), plus depreciation $52.5m ÷ 1.08 = $48.61m. Site (capacity factor) Generation (MWh a year) PTC a year PV of PTC route PV of ITC route Better choice Weak, 15% 262,800 $8.15m $100.00m $105.97m ITC by $5.98m Average, 20% 350,400 $10.86m $117.13m $105.97m PTC by $11.15m This project, 25% 438,000 $13.58m $134.25m $105.97m PTC by $28.28m The flip point.
Decision rule
First check eligibility: when did physical work of a significant nature begin, and will the plant be in service by December 31, 2027, if construction began after July 4, 2026? Then, if the expected capacity factor is above the flip point — about 17% at the prices in this case, about 20% with the energy-community bonus on both credits — elect the PTC; below it, elect the ITC.
The costliest mistake
Missing the placed-in-service deadline. Suppose a sponsor relied on paying for 5% of equipment cost in June 2026 instead of starting physical work. Under Notice 2025-42 that does not begin construction, so construction legally starts after July 4, 2026, and the plant must be in service by December 31, 2027. If interconnection delays push it into 2028, the credit is lost entirely. At a 25% capacity factor, NPV falls from +$45.2 million (PTC) to −$40.4 million (no credit): a swing of 45.2 − (−40.4) = $85.6 million on a $250 million project.
Recap
A US solar project’s return turns on federal energy tax: the 48E investment credit versus the 45Y production credit, 100% bonus depreciation reduced by half of any ITC, and the OBBBA’s begin-construction and placed-in-service deadlines. In this case the production credit wins above a 16.7% capacity factor, and missing the deadline would cost about $86 million of value.
What the full article covers
The full article includes worked examples, a look under the hood at the mechanics, a clear decision rule, the one mistake that costs people the most, a recap, a reveal-on-click quiz and the official sources behind every figure.
Volume III: Finance Encyclopedia
Read the full article on FinoLib
The complete article, Solar Project Finance: 48E vs 45Y Tax Credits Explained, with every worked example, diagram, quiz and source, is free to read in Volume III, Finance Encyclopedia on finolib.com.
Explore the Finance Education Series: Vol. II — Capital Markets · Vol. I — Global Economy · Vol. III — Finance Encyclopedia · Vol. IV — Finance Careers · Vol. V — Personal Finance