How Storage (BESS) Raises Self-Consumption — The Post-Netting Profit Logic

The problem: midday surplus, evening demand

Solar generates most at midday, while homes and many businesses peak in the evening. Under hourly netting this timing gap hits revenue directly: surplus not consumed by day won't cover expensive evening electricity.

The fix: time-shifting with a battery

BESS stores the daytime surplus and serves it to evening load. The new regulation allows storage at an unlicensed plant up to the plant's electrical installed power, raising self-consumption and cutting purchases during expensive hours.

Profit logic: the peak price spread

Value comes from the intraday price spread. Per EPİAŞ data, in a sample week at end-2025 peak hours (17:00–22:00) averaged ~3,375 TL/MWh versus ~2,676 TL/MWh at night — about a 26% gap. Using stored solar at the expensive peak (or in grid services) converts that spread into income.

Round-trip efficiency and sizing

• Modern lithium (LFP) batteries have a round-trip efficiency of 85–95%; you recover most of what you store.
• Size the battery so daytime surplus and evening demand overlap on an hourly basis.
• An oversized battery lengthens payback; the right size follows self-consumption and peak needs.
• Remember surplus fed from storage to the grid is uncompensated — design the battery primarily for self-consumption and peaks.

Who is it for?

Residential complexes, hotels, malls and shift-based industry with high evening/night load are strong candidates. A hybrid setup combining solar and BESS at one connection point maximises both self-consumption and returns; see our hybrid plant article.