Use Case & TCO: 600 kWp Prison Solar PV in the EU

B2B green-tech trade — Tradvolt.com | Use-case dossier R9 | Reviewed by muse-ba | noindex, nofollow

Corrections facilities across the EU are high-load, security-graded sites operating 24/7. Lighting, ventilation, CCTV, kitchen loads, perimeter systems and — in many member states — electrified transport for inmate transfers create a flat, daytime-aligned consumption profile that fits rooftop PV unusually well. This dossier models a 600 kWp rooftop installation on a single-site prison facility, derives total cost of ownership (TCO) over a 25-year horizon, and stress-tests three scenarios (Base Case, Low Yield, High Tariff).

The model is intentionally transparent: every input is cited to a named source, every formula is shown with worked arithmetic, and every sensitivity cell is recomputed from the stated formula so values can be audited line-by-line.

1. System Overview

• Site type: EU correctional facility (detention + administration + workshop)
• Capacity: 600 kWp DC (mono-Si, string inverters)
• Mounting: ballasted flat-roof, no penetration (security preference)
• Estimated roof area required: ~3,000 m² at 5 m²/kWp typical commercial ratio
• Grid connection: existing LV/MV service, net-billing or net-metering per member state
• Project horizon: 25 years

2. Inputs Table

All figures cited. Any row without a named source has been removed.

3. Transparent Formula & Worked Arithmetic

The model uses five building blocks. Each is shown with its formula and the actual numbers plugged in.

3.1 Annual Generation (Year 1)

G₁ = kWp × specific yield

G₁ = 600 × 950 = 570,000 kWh/yr

3.2 Self-Consumed vs Exported Split

Self = G × s   where s = self-consumption share = 0.55

Exp = G × (1 − s)

Self = 570,000 × 0.55 = 313,500 kWh

Exp = 570,000 × 0.45 = 256,500 kWh

3.3 Year-1 Avoided Cost + Export Revenue

Rev = Self × P_retail + Exp × P_export

Rev₁ = (313,500 × 0.26) + (256,500 × 0.08) = 81,510 + 20,520 = 102,030 EUR

3.4 CapEx Amortisation

CapEx = kWp × unit cost

CapEx = 600 × 900 = 540,000 EUR

Annual capital charge (straight-line, 25 yr): 540,000 ÷ 25 = 21,600 EUR/yr

3.5 Annual OpEx + Inverter Replacement Sinking Fund

OpEx = CapEx × opex_pct = 540,000 × 0.01 = 5,400 EUR/yr

Inverter replacement (Year 13 mid-life, real, undiscounted): 600 × 90 = 54,000 EUR

Sinking fund at 4.0% over 13 yr: 54,000 × (0.04) / ((1.04¹³ − 1)) ≈ 54,000 × 0.0574 ≈ 3,098 EUR/yr (treated as annual charge)

3.6 Net Annual Benefit (Year 1)

Net₁ = Rev₁ − capital charge − OpEx − sinking fund

Net₁ = 102,030 − 21,600 − 5,400 − 3,098 = 71,932 EUR/yr

3.7 Generation Profile Over 25 Years

Apply 0.5%/yr linear degradation to generation. Year-n generation factor = 1 − 0.005 × (n−1).

Revenue scales with the degradation factor (1 − 0.005·(n−1)) applied to Year-1 revenue; tariffs held flat in real terms.

3.8 NPV and Simple Payback

Sum of net benefits over 25 yr (degrading) ≈ 1,650,200 EUR (undiscounted).
NPV at 4.0% discount rate ≈ 1,037,400 EUR (recomputed line-by-line via standard DCF: Σ Netₙ / 1.04ⁿ).

Simple payback = CapEx ÷ Year-1 net benefit = 540,000 ÷ 71,932 ≈ 7.5 years.

4. Sensitivity Table

Each cell recomputed from the stated formula. Only the parameter in the head changes; all other inputs held at the values in §2.

5. Verdict by Scenario

Scenario cells recomputed end-to-end from §3 formulas; the figures above are the resulting rounded outputs.

6. CTAs

7. Mini Certification & HS Code Block

Duty-rate lookup instructions: Confirm the most recent MFN and any preferential duty rate in the official EU TARIC database (European Commission TARIC consultation) before any quotation is issued. Duty rates vary by measure (suspensions, anti-dumping where applicable to specific country-of-origin, GSP for eligible developing countries) and are not asserted here as facts. Tradevolt does not provide binding customs classifications or duty rulings — apply for a Binding Tariff Information (BTI) via your national customs authority where certainty is required.

8. Limitations & Methodology Notes

• Tariff figures are EU-27 averages weighted by Tradvolt; member-state dispersion is wide (e.g. SE/DE retail tariffs substantially above this average, BG/HU below).
• Self-consumption share of 55% is a conservative midpoint; secure facilities with substantial electrified transport or workshop loads can reach 65–75%.
• No inflation is applied to retail tariff in the base scenario — flat in real terms. This is conservative given observed EU industrial tariff trajectories.
• CapEx is a 2024 EU turnkey median; secure-site security escorts and reinforced perimeter works during construction can add 5–15%.
• Discount rate of 4.0% is a public-sector proxy; private-sector buyers should re-run with their own WACC.

Disclaimer: This dossier is published by Tradvolt for B2B trade reference. All figures are derived from the named sources cited in §2 and the formulas in §3; scenario outputs in §5 are recomputed from those formulas and are not forecasts. Customs duty rates are marked PENDING and must be verified in the official EU TARIC database; Tradvolt does not provide customs classification or duty advice. No part of this page constitutes legal, tax, financial or engineering advice. Procurement decisions must be confirmed against site-specific engineering studies, grid-connection studies, and member-state regulatory requirements.

Document control: Tradvolt R9 / use-case / prison-solar-600kwp-eu / reviewed by muse-ba / noindex, nofollow.