FAQ
TL;DR: For a C21 plant using 250–300 MWh/month, 1 kWp yields ~1,000 kWh/year; "large installations without subsidies are not very profitable." Expect weak ROI unless incentives or optimized sizing apply. [Elektroda, Xantix, post #17156936]
Why it matters: This FAQ helps plant managers and CFOs evaluate PV ROI for two‑shift loads under Poland’s C21 tariff.
- Micro-PV cap is 40 kW; ~1,000 kWh/kWp/year means ~40,000 kWh/year max—tiny versus 250–300 MWh/month. [Elektroda, Xantix, post #17156936]
- Example PVGIS run: 400 kWp ≈ 384,000 kWh/year; best months stay <50,000 kWh. [Elektroda, hupo, post #17157135]
- Size to daytime base load; if base ≈500 kW, target ≈500 kWp ±10%; east–west can help. [Elektroda, Jack3030, post #17157160]
- Example costs: ~190 PLN/MWh energy + ~170 PLN/MWh daytime transmission; PV offsets both. [Elektroda, Jack3030, post #17157201]
- Insurance handling proved unclear and potentially costly; contract pricing risk flagged when grid draw falls. [Elektroda, Ryszard49, post #17157483]
Quick Facts
- Micro-PV cap is 40 kW; ~1,000 kWh/kWp/year means ~40,000 kWh/year max—tiny versus 250–300 MWh/month. [Elektroda, Xantix, post #17156936]
- Example PVGIS run: 400 kWp ≈ 384,000 kWh/year; best months stay <50,000 kWh. [Elektroda, hupo, post #17157135]
- Size to daytime base load; if base ≈500 kW, target ≈500 kWp ±10%; east–west can help. [Elektroda, Jack3030, post #17157160]
- Example costs: ~190 PLN/MWh energy + ~170 PLN/MWh daytime transmission; PV offsets both. [Elektroda, Jack3030, post #17157201]
- Insurance handling proved unclear and potentially costly; contract pricing risk flagged when grid draw falls. [Elektroda, Ryszard49, post #17157483]
Is PV profitable under C21 for ~250–300 MWh/month and two-shift production?
The OP closed the thread with: “With the current tariff (C21) and solar installation costs, the project is unprofitable.” That reflects a high-consumption, two-shift profile and the prices discussed there. Recheck ROI with your current quotes and any incentives before deciding. [Elektroda, Ryszard49, post #17204041]
How much electricity can a 400 kWp PV plant produce in central Poland?
A PVGIS example for 53.357N, 19.734E showed ~384,000 kWh/year. Even in the two best months, output stayed under 50,000 kWh. The case assumed fixed-tilt 35° and south orientation. Use PVGIS to validate for your exact site and mounting scheme. [Elektroda, hupo, post #17157135]
Does Poland’s climate zone decide PV profitability?
An expert response stated, “The climate zone does not matter here, only the amount of funding or the purchase price of energy.” Incentives and offtake terms drive ROI more than minor irradiance differences within Poland. [Elektroda, Xantix, post #17157032]
How should we size PV versus our base load?
Match PV capacity to the daytime base load so you self-consume almost all generation. If your load is ~500 kW steady, aim near 500 kWp ±10%. East–west arrays can stretch production and reduce noon peaks. “They need to determine their wear profile.” [Elektroda, Jack3030, post #17157160]
Do micro‑installations (≤40 kW) make sense for this plant?
Not for this usage. 1 kWp yields about 1,000 kWh/year, so 40 kW gives ~40,000 kWh/year—roughly a week’s consumption here. As one user put it, “the profitability is negligible.” Micro prosumer rebates also don’t scale to this load. [Elektroda, Xantix, post #17156936]
Are large PV plants viable without subsidies?
The thread’s takeaway: larger-than-40 kW plants act like professional generators, and incentives matter. “Large installations … without subsidies … are not very profitable.” Model scenarios with and without support to see the gap. [Elektroda, Xantix, post #17156936]
What do C21 energy and transmission charges look like at scale?
One contributor cited ~190 PLN/MWh for energy and ~170 PLN/MWh daytime transmission. PV that is self-consumed offsets both cost components during sunny hours. Use your negotiated price sheet to refine savings. [Elektroda, Jack3030, post #17157201]
What payback did the thread’s example 400 kWp calculation suggest?
Using a ~1.5 million PLN project cost and the cited yield, an example estimate landed near 13 years in a best case. It depended on assumed MWh pricing and strong self-consumption. Validate with your actual profile. [Elektroda, hupo, post #17157135]
How do I plan a PV system for two‑shift operations? (3‑step quick start)
- Map your 15‑min load to find the daytime base profile.
- Size PV around the base load (±10%) to minimize exports.
- Consider east–west strings to flatten output against your shift timing. “They need to determine their wear profile.” [Elektroda, Jack3030, post #17157160]
What budget and monthly bill did the OP report?
An initial turnkey offer was ~1.5 million PLN for the project. The company’s monthly electricity bill at that time was about 57,000 PLN. Use these only as context; your quotes and bills will differ. [Elektroda, Ryszard49, post #17157004]
What hardware and warranty risks can hurt ROI?
Plan for inverter replacements and warranty gaps. As noted, “Within 15 years, inverters without a long-term warranty will be a burden on the owner.” Budget OPEX beyond panel cleaning, including monitoring and potential repairs. [Elektroda, hupo, post #17157192]
What happens if we oversize PV versus our draw?
Oversizing can reduce savings. Plant load varies, so surplus midday energy may not be used for balancing, worsening the final bill. “These 400 kWp may be too much … which will worsen the final bill.” Right-size to base load to avoid this edge case. [Elektroda, hupo, post #17157135]
Will a medium‑voltage (sN) multi‑zone tariff change payback?
Yes. sN multi‑zone tariffs lower grid energy rates, so PV pays back more slowly. One user’s analysis led to a smaller, more profitable install; they also noted sN connection was impractical due to cable distance. EFI‑State handled their optimization. [Elektroda, damianssj661, post #17197460]
Could my supplier change the price if my grid consumption drops?
This contract risk was explicitly raised in the thread. Confirm terms with your supplier before commissioning PV. Seek clauses that preserve your unit price or define thresholds for renegotiation. [Elektroda, Ryszard49, post #17157483]
What panel lifetime did a bidder assume?
One bidder modeled a 15‑year panel lifetime for this project. Align your ROI horizon with warranted performance and planned component refresh cycles. [Elektroda, Ryszard49, post #17157074]
How hard is it to insure a large PV installation?
The OP reported insurer uncertainty. A PZU representative “had no idea how to approach” the case and indicated the annual fee could be very high. Engage insurers early and request written terms. [Elektroda, Ryszard49, post #17157483]
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