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[Solved] Solar Installation Profitability: C21 Tariff, 250k-300k kWh Consumption, Two Shift Production

Ryszard49 6066 17
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Is it cost-effective for a company on C21 tariff with monthly consumption of 250,000–300,000 kWh and two-shift production to install a photovoltaic system?

With the current C21 tariff and solar installation costs, the project is considered unprofitable unless you have subsidies or a very favorable purchase price for the generated energy [#17204041][#17156936][#17157032] For a business like this, the installation has to be sized against the actual consumption profile, because only the energy used on an ongoing basis really pays off; excess production is sold on less favorable terms [#17157160][#17157201] Several replies note that such a project depends heavily on financing, fixed costs, and the exact installed power, so a precise profitability calculation cannot be done from monthly kWh alone [#17156948][#17157536] One reply estimates that a 400 kWp system in this climate would generate about 384,000 kWh/year, with the best months around 47–50 MWh, and suggests that without support the payback can stretch to roughly 13 years [#17157135]
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  • #1 17156897
    Ryszard49
    Level 39  
    Hello.
    I have a query for people using solar farms. Is it cost effective to install a photovoltaic installation in a company with a C21 tariff, monthly electricity consumption of 250,000 - 300,000 kWh? Two shift production.
    Regards.
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  • #2 17156936
    Xantix
    Level 41  
    In the micro-installation system, those that have up to 40 kW of power are caught - such use the so-called rebates that are quite a good solution. Each 1 kWp of such an installation will produce 1000 kWh of electricity a year. Thus, the largest available micro-installation will produce 40,000 kWh annually - as much as the company uses during the week. As you can see, the profitability is negligible.

    Larger installations already operate as professional power generators, and here the matter is very complicated - you need a person with a doctorate to calculate the profitability of the entire project. One thing is certain - large installations (those over 40 kW) without subsidies in the form of green certificates etc. are not very profitable.
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  • #3 17156948
    hupo
    Level 14  
    It depends on the way (to) financing the investment, what fixed costs, e.g. for the lease of land for installation, etc. 500kW of average power consumption is very much and you need to put these PV a bit to change the situation :-) .
    C21 is a tariff for low voltage consumption. A little terrible power on Does this mean that the transformer station is the property of the operator and it supplies power to many customer points already as nn ?.
  • #4 17157004
    Ryszard49
    Level 39  
    hupo , own transformer station exclusively for the company.

    Added after 4 [minutes]:

    The point is whether it is profitable in our climate zone, one of the initial offers amounts to PLN 1,500 thousand for the overall project implementation. The current monthly cost for electricity is about 57,000. zlotys.
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  • #5 17157032
    Xantix
    Level 41  
    Ryszard49 wrote:
    It's about whether it's profitable in our climate zone,

    The climate zone does not matter here, only the amount of funding or the purchase price of energy from renewable energy installations - it determines the profitability of investments in PV.
  • #6 17157046
    Ryszard49
    Level 39  
    Xantix , I would prefer that users of such installations asked about this topic. There is no place here for craving, it is really big money.
  • #7 17157064
    Xantix
    Level 41  
    Ryszard49 wrote:
    I would prefer users of such installations to ask about it.

    And I rather doubt that the owners of solar power plants were here on the forum.

    Ryszard49 wrote:
    There is no place here for craving, it is really big money.

    And because they are it really big money then you can spend a relatively small amount and hire a professional company that deals with the design and calculation of the profitability of this type of investment? ;)
  • #8 17157074
    Ryszard49
    Level 39  
    Xantix in post # 4 I have clearly described the offer we received, the opinion with an opinion but I would prefer someone who uses such an installation to speak. I have read that in this particular case the bidder estimates the panels for 15 years of use.
  • #9 17157089
    Xantix
    Level 41  
    Ryszard49 wrote:
    I clearly described the offer we received

    You didn't write anything. The amount of money paid for the installation says nothing about it.

    Ryszard49 wrote:
    but I would prefer someone who uses such an installation.

    What? Give some parameters of this installation, even electric power - without that you can look at grounds.
  • #10 17157098
    Ryszard49
    Level 39  
    Xantix , I gave electricity consumption per month, about 300,000 kWh and there are plans to buy several injection molding machines.
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  • #11 17157135
    hupo
    Level 14  
    As for profitability, my intuition tells me that without funding and entering the system like a father does not make sense but as already mentioned in the forum it is difficult to calculate.
    "PLN 1,500 thousand for the overall project implementation" for how much installation capacity? let's assume 400kWp?
    In practice, the power consumed by the plant will not be even, there will be jumps and these 400kWp may be too much (the current power for balancing will not be used), which will worsen the final bill.

    Returning to the question of what power will be generated from the installation of a specific power is a fairly accurate answer can be found on the site "PVGIS for Europe". As you can see from 400kWp only less than 50,000kWh per month in the two best months and 384,000 per year. I do not know such high connection capacity but 250MWh for PLN 75 thousand with transmission is probably very cheap? with such prices without subsidies, the payback period is 1500 / (at best (384000/250000) * 75) in the best case = 13 years?

    PVGIS estimates of solar electricity generation
    Location: 53 ° 21'26 "North, 19 ° 44'3" East, Elevation: 142 m asl,

    Solar radiation database used: PVGIS-CMSAF

    Nominal power of the PV system: 400.0 kW (crystalline silicon)

    Fixed system: inclination = 35 °, orientation = 0 °
    Month Ed Em Hd Hm
    Jan 285.00 8820 0.83 25.6
    Feb 542.00 15200 1.61 45.0
    Mar 1200.00 37100 3.70 115
    Apr 1620.00 48600 5.22 157
    May 1670.00 51900 5.59 173
    Jun 1660.00 49800 5.61 168
    Jul 1530.00 47 400 5.24 163
    Aug 1470.00 45600 4.98 154
    Sep 1230.00 36900 4.01 120
    Oct 818.00 25 400 2.57 79.5
    Nov 351.00 10500 1.06 31.9
    Dec 224.00 6930 0.66 20.4
    Total yearly 384000

    Ed: Average daily electricity production from the given system (kWh)
    Em: Average monthly electricity production from the given system (kWh)
    Hd: Average daily sum of global irradiation per square meter received by the modules of the given system (kWh / m2)
    Hm: Average sum of global irradiation per square meter received by the modules of the given system (kWh / m2)
  • #12 17157160
    Jack3030
    Level 15  
    Xantia, what are you writing about? What discounts? This investment should only consider installations that produce as much energy as the company consumes on an ongoing basis. They need to determine their wear profile. If the load is constantly at a level of e.g. 500kW, then only 500kWp + - 10% installation pays off. Unless it's an east-west installation. The profitability can be calculated by setting the cost of 1 MWh that this company now has. The above installation will produce 500MWh in the year. Each larger installation will generate kWh, which they will not consume on a current basis, and for each kWh they will receive some amount, which is not the average from the previous quarter. Each grant will improve the financial conditions.
  • #13 17157192
    hupo
    Level 14  
    We want to help as much as we can, please do not be nervous and provide data on the power of the proposed PV installation. Information that
    Ryszard49 wrote:
    the bidder estimates the panels for 15 years of use.
    is typical and insufficient. Within 15 years, inverters without a long-term warranty will be a burden on the owner. The way the installation is carried out in the field may be relevant. You won't run away from the cost of insurance.
  • #14 17157201
    Jack3030
    Level 15  
    With such consumption, the negotiated price for energy is probably PLN 190 / MWh + daytime transmission cost around PLN 170 / MWh and the PV installation replaces these total costs.
  • #15 17157483
    Ryszard49
    Level 39  
    hupo , today I started the day collecting information on installation insurance, I chose PZU, and here a small zonk, the representative has no idea how to approach this particular topic. But he said the annual fee could be very high. Then the question arises whether, if the consumption of electricity decreases, the supplier will not change the price for 1kWh?
  • #16 17157536
    hupo
    Level 14  
    Once again, just like Xantix before, please give the parameters (first of all power) of the PV installation you were offered. Without this information, the discussion loses its meaning. If it were the power I wrote about earlier, then the reduction in consumption would be no more than 30% and only for a few months of the year, but it is only my "shag".
  • #17 17197460
    damianssj661
    Level 10  
    I do not know if it is possible to advertise in this way, but for us in Tarnów, the profitability of PV and optimization was counted by the company (efi state.pl). We had a consumption of about 80MWh / mc, but around the clock (70% during the day) and ultimately we made the installation smaller than intended, but apparently the most profitable and bills smaller as expected.

    For such high consumption it is good to have a multi-zone tariff in sN and then the PV returns much slower (cheaper EE from the network), but in Poland it was too far to the sN cable and such a connection could not be made.
  • #18 17204041
    Ryszard49
    Level 39  
    With the current tariff (C21) and solar installation costs, the project is unprofitable.
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Topic summary

✨ The discussion revolves around the cost-effectiveness of installing a photovoltaic (PV) system for a company with a C21 tariff and a monthly electricity consumption of 250,000 - 300,000 kWh, operating on a two-shift production schedule. Participants highlight that micro-installations (up to 40 kW) may not be profitable without subsidies, while larger installations require complex calculations for profitability. Factors influencing profitability include financing methods, land lease costs, and energy purchase prices. The importance of matching installation capacity to consumption patterns is emphasized, with suggestions to consult professional companies for accurate assessments. Concerns about installation insurance costs and potential changes in electricity pricing with decreased consumption are also raised. Overall, the consensus leans towards the project being unprofitable under the current tariff and installation costs.
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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.

Quick Facts

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)

  1. Map your 15‑min load to find the daytime base profile.
  2. Size PV around the base load (±10%) to minimize exports.
  3. 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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