Distribution fees in unlicensed generation: withdrawal, injection and on-site self-consumption

A common mistake in unlicensed solar feasibility is to build savings only as “generation × energy unit price”. In the hourly netting period, distribution fees — on both the withdrawal and injection sides — directly shift net profit and payback. This article puts distribution fees in unlicensed generation at the centre: injection charges are a cost that would not exist without the plant; the withdrawal discount is a saving on a line that would be billed with or without solar. The third and strongest layer is generation consumed on site before it ever reaches the bidirectional meter — those kWh attract no distribution fee at all.

Three distribution layers in unlicensed generation

Injection side: a cost of the plant

Injection distribution is the system-use charge paid to the distribution company for each kWh delivered to the grid. Without a solar plant this line would not appear on the bill. Treat it as part of operating cost — not merely a “side cost of energy sales”. The unit rate depends on the Unlicensed Producer-1 / Producer-2 band and whether the plant has completed ten years — details are in our ten-year unlicensed solar distribution-fee guide.

Under 5.1c (same metering point) the injection base is typically only surplus sales: netted kWh do not generate an injection invoice line. Under 5.1h (separate metering) the base usually spans the net generation band — so injection cost is higher for the same kWh profile. Type formulas are in our 5.1c vs 5.1h distribution feasibility article.

Withdrawal side: the discount is profit

Withdrawal distribution is the charge the consumption subscriber already pays for energy taken from the grid. Consumption would continue without solar, so the distribution bill would still exist. At the same metering point (5.1c), after hourly netting a 50% discount applies on the netted kWh. That discount is avoided cost — booked straight into net profit and payback — because the no-solar reference would have paid the full tariff on the same consumption.

Behind-the-meter self-consumption: fee-free kWh

The bidirectional meter sees only the net exchange with the grid. When generation is consumed on the load side before it reaches the meter — panels to inverter to board to machine — those kWh attract neither withdrawal nor injection distribution. Netting is the overlap the meter sees; behind-the-meter self-consumption is a deeper economic layer. In feasibility and operations the goal is to align generation with load in the same hour and on the same site: generate on site, consume on site.

Hourly netting — 5.1c scenarios

Figures below use example units (not official EMRA tariffs) to show the base. Assumptions: withdrawal unit = 1.00 TL/kWh, injection unit = 0.66 TL/kWh. The energy side of hourly netting is in our Hourly Netting 2026 guide; here we clarify the money side — what is paid and what is discounted.

Hour A — generation 100 kWh, consumption 80 kWh

• No injection fee on the 80 kWh netted — only the 20 kWh sold enter the base.
• The 50% discount on 80 kWh saves half of what full-tariff withdrawal would have cost without solar.
• Same-hour generation–consumption overlap pays off on both energy and distribution.

Hour B — generation 40 kWh, consumption 100 kWh

Without solar, withdrawal distribution would be 100 kWh × 1.00 = 100 TL. With solar the example bill is 80 TL; the 20 TL gap is the netting discount. Injection cost is zero in this hour — nothing is sold to the grid.

Hour C — generation 120 kWh, consumption 0 kWh

This hour shows the cost of “generation with no on-site load”. Even with energy sales revenue, injection distribution cuts like an operating expense. Midday generation / night load profiles create many such hours; batteries or shift changes that raise overlap shorten payback.

Short contrast with 5.1h

Under standard 5.1h (separate metering) Hour A’s 50% withdrawal discount does not apply, and the injection base approaches the net generation band. For the same 100/80 profile the distribution side is weaker than 5.1c. Hybrid 5.1h with on-meter internal load can still get a partial 50% discount in product logic — the main split remains same metering vs separate metering.

How it feeds payback

Annual net distribution effect ≈ Σ (withdrawal savings − injection cost) + full withdrawal fees avoided by behind-the-meter self-consumption. Added to energy netting savings and sales revenue, this grows annual net benefit; CAPEX / annual net benefit ≈ payback. An injection-heavy profile (many Hour-C hours) lengthens payback; a daytime load that overlaps generation (Hours A/B + behind-the-meter) shortens it.

ENOPTIMAL — make distribution visible

In ENOPTIMAL netting management, hourly netting, withdrawal distribution savings and injection cost are tracked in one flow; the distribution breakdown compares the no-solar reference with the expected bill. Choosing the correct plant type (5.1c / 5.1h) in feasibility is required for these bases to land in the model. In operations the OSOS hourly profile answers “in which hours do we fall into injection cost?” — shift, storage or load-shift decisions to raise on-site consumption become data-driven.

Conclusion

Read distribution fees in unlicensed generation in three layers: injection is a plant cost, the withdrawal discount is plant profit, and behind-the-meter on-site consumption is fee-free kWh. Hourly 5.1c scenarios show that every netted kWh brings both energy value and a 50% withdrawal discount, while surplus turns into injection cost. The path to a shorter payback is clear: generate on site, consume on site — maximise physical overlap.