Capturing the Evening Price Spread from Midday Solar —
Project Overview
Project Background
The solar farm exported all of its output directly to the grid, but the timing of generation worked against the plant’s revenue. PV output concentrated in the middle of the day, which is also when wholesale export prices were typically at their lowest. Higher-value pricing windows fell in the evening, after solar production had already tailed off.
With generation and value misaligned, the plant was leaving revenue on the table and at times exposed to negative or near-zero midday prices.
Project Challenge
- Midday PV output peaked exactly when grid export prices were at their lowest.
- Surplus solar risked curtailment and inverter clipping during peak production hours.
- The plant needed to defer that surplus to the evening to capture the price spread without re-engineering the existing 800V PV system.
FFD POWER Solution
FFD POWER supplied five Galaxy418L all-in-one BESS units, AC-coupled to the existing 800V PV inverters on a shared 800V bus. AC coupling lets the battery integrate alongside the installed inverters without modifying the DC side of the array, so the storage absorbs surplus solar at midday and releases it in the evening as a straightforward retrofit.
System Specifications
- Five Galaxy418L all-in-one units, 210 kW / 418 kWh each.
- Aggregate system rating: 1,050 kW / 2,090 kWh.
- AC-coupled to the existing 800V PV inverters on a shared 800V bus.
- Application: PV energy arbitrage.
Operational Logic: The "Arbitrage Hub" Strategy
- The EMS coordinates PV, battery and grid against the daily price profile.
- Midday charge: when PV output is high and export prices are low, the system charges the batteries from surplus solar that would otherwise be exported cheaply or clipped.
- Evening export: when prices rise, the batteries discharge to the grid to capture the spread.
- Because the surplus that drives charging is the same energy that would have been curtailed at midday, the single charge-and-export cycle both captures the price spread and reduces curtailment.
