CAISO Curtailment Risk for Solar Projects

CAISO Curtailment Risk for Solar Projects

California solar curtailment is now large enough to require an explicit lender model rather than a generic production haircut. Oversupply, local congestion and negative prices can all reduce delivered MWh even when the plant is mechanically available.

The current technical framework is set out in CAISO Managing the Evolving Grid and CAISO May 2026 Monthly Renewables Report. These references are applied specifically to the underwriting analysis in CAISO Curtailment Risk for Solar Projects.

Credit Relevance of Caiso Solar Curtailment Underwriting

CAISO reports that most renewable curtailment continues to be solar. Its May 2026 monthly renewables report recorded roughly 1.36 million MWh of solar energy curtailed, and the ISO explains that curtailment is especially common during sunny, low-load spring and fall periods. For a project lender, the issue is not whether curtailment exists in the market; it is whether the project model captures the location, timing and contractual allocation of that lost output.

Build curtailment by month and hour, not as a constant annual percentage. The lender case should distinguish system-wide oversupply from local congestion and test whether battery charging or PPA deemed-energy provisions offset the lost revenue. That approach makes congestion, dispatch and storage assumptions auditable instead of burying them inside a single annual generation haircut.

Underwriting Tests for Caiso Solar Curtailment Underwriting

• 1. monthly curtailment profile.
• 2. local congestion.
• 3. negative-price intervals.
• 4. PPA compensation.
• 5. storage charging window.
• 6. WEIM export assumptions.
• 7. transmission development.

Documents Required for Caiso Solar Curtailment Underwriting

The lender file should let a credit committee reproduce the assumption without relying on management narrative. For CAISO solar curtailment underwriting, the following items should be current and internally consistent.

• CAISO curtailment history.
• node and DLAP price data.
• PPA curtailment clause.
• battery dispatch model.
• transmission study.
• resource forecast.

Failure Modes in Caiso Solar Curtailment Underwriting

• Using a market-wide curtailment percentage for CAISO solar curtailment underwriting instead of node-specific evidence.
• Flooring negative prices at zero in the debt model.
• Assuming storage can absorb all curtailed output without interconnection or state-of-charge constraints.
• Ignoring how the PPA allocates economic, grid-directed and buyer-directed curtailment.

For CAISO solar curtailment underwriting, the bankable approach is granular: node, hour, dispatch rule, contract and hedge. Market averages are useful context, but the lender is repaid by the project’s realized settlement path.

FAQ About Caiso Solar Curtailment Underwriting

How should lenders model CAISO solar curtailment underwriting? — CAISO Curtailment Risk for Solar Projects

For CAISO Curtailment Risk for Solar Projects, lenders should use location-specific price, dispatch and curtailment evidence for CAISO solar curtailment underwriting, then reconcile the market exposure to the PPA, hedge and storage strategy.

Does a PPA eliminate CAISO solar curtailment underwriting? — CAISO Curtailment Risk for Solar Projects

For CAISO Curtailment Risk for Solar Projects, no. A PPA may compensate some curtailment or basis exposure, but the exact result depends on settlement point, deemed-energy language, negative-price rules and curtailment carve-outs.

Can battery storage solve CAISO solar curtailment underwriting? — CAISO Curtailment Risk for Solar Projects

For CAISO Curtailment Risk for Solar Projects, storage can reduce some lost-energy exposure, but only within interconnection limits, inverter capacity, state-of-charge, duration and cycling constraints. The lender model should not assume perfect recovery.