A year-round 38 m² modular home with a heat pump uses about 5,500 kWh of electricity per year. A 5 kWp solar system with a battery covers 80% of that demand and pays back in 6–7 years. Below is the full cost breakdown in EUR, a system comparison and a realistic payback scenario under Polish 2026 net-billing rules.
Before you can size the panels, you need to know your consumption. A typical year-round 38 m² modular home with an air-to-water heat pump and standard appliances uses per year:
Total: 4,600–6,600 kWh per year. For a safe calculation we use 5,500 kWh — the average for a well-insulated 38 m² home occupied by two people all year.
Under Polish conditions, 1 kWp of installed capacity produces on average 950–1,050 kWh per year (northern coast: 1,020 kWh, southeast: 1,100 kWh, central regions: 970 kWh). To cover 5,500 kWh you need a 5.5 kWp system.
In practice the market standard is to round up to 5 kWp or 6 kWp:
The roof of a 38 m² modular home is typically 40–45 m² — more than enough space, even for a 6–8 kWp system that leaves room for a future EV charger.
The simplest case. Panels are mounted parallel to the roof surface on an aluminum rail system, clamped to the standing-seam metal or screwed into the rafters. Optimal angle in Poland: 30–35°, south-facing azimuth. East-west orientation loses roughly 10–15% of yield but spreads production across the day — a plus if you have no battery.
The standard roof on a 38 m² modular home. Requires a ballasted mounting system in aluminum, tilting the panels at 10–15°. That system weighs 15–20 kg/m² with concrete ballast — the modular roof has to be engineered with load capacity to spare. All of our year-round models carry at least a 25 kg/m² reserve for additional loads.
Downsides of a flat roof: yield is 5–8% lower than at the optimal 30° angle, and in winter snow lingers longer and blocks production. Upsides: no scaffolding needed, easy maintenance.
Market prices in Poland, August 2026, converted at 4.50 PLN/EUR. For a 5 kWp system on a modular home roof:
| Item | Price EUR | Notes |
|---|---|---|
| 13 monocrystalline 400 W panels | 1,950 | 150 EUR each, Tier 1 class |
| Hybrid inverter 5 kW | 1,300 | 3-phase with battery input |
| Ballast mounting structure | 650 | Aluminum + concrete ballast |
| DC/AC wiring, protection | 450 | SPD, breakers, solar cables |
| Installation and commissioning | 950 | 2 days, 3-person crew |
| Grid operator paperwork, design | 250 | Documentation, bidirectional meter |
| Total without battery | 5,550 | ≈ 25,000 PLN |
| Battery storage 10 kWh (LiFePO4) | 4,450 | Optional, but changes the economics |
| Total with 10 kWh battery | 10,000 | ≈ 45,000 PLN |
These are turnkey prices including tax. Market spread: 4,800–6,500 EUR without a battery, 9,000–12,000 EUR with a battery — depending on inverter brand (Sungrow, Fronius, Huawei) and panel class.
The simplest and cheapest setup. Panels plus inverter, no battery. Surplus energy goes to the grid; at night you draw from the grid. The downside is the Polish net-billing model: you sell energy cheap (monthly average market price) and buy it back expensive (retail tariff plus distribution fees). Realistic balance: 30–40% of the value of exported energy comes back to you as a lower bill.
Panels plus a large battery plus a backup generator, with no connection to the grid operator. Only makes sense on plots with no access to power (connection cost above 15,000 EUR) or for recreational homes. It requires a 15–20 kWh battery; the total cost is 15,000–20,000 EUR. Not recommended for a year-round 38 m² home — in November through February production drops to 5–10% of the annual average.
Panels plus hybrid inverter plus a 5–15 kWh battery plus grid connection. The battery charges during the day and discharges in the evening and at night. Self-consumption jumps from 30% (on-grid) to 70–85%. As a bonus it provides backup power during blackouts. This is the most cost-effective model for a year-round modular home in Poland in 2026.
Assume a 38 m² home with annual consumption of 5,500 kWh. Grid electricity price: 0.95 PLN/kWh including tax (0.21 EUR). Sale price for surplus energy (average market rate): 0.35 PLN/kWh (0.08 EUR).
| System | Cost EUR | Yield kWh/year | Savings EUR/year | Payback (years) |
|---|---|---|---|---|
| 3 kWp on-grid | 3,800 | 3,000 | 420 | 9.0 |
| 5 kWp on-grid | 5,550 | 5,000 | 640 | 8.7 |
| 5 kWp + 10 kWh battery | 10,000 | 5,000 | 950 | 10.5 |
| 6 kWp + 10 kWh battery | 10,900 | 6,000 | 1,100 | 9.9 |
After subtracting the Mój Prąd 6 (Polish solar subsidy program) grant described below, payback drops to 6–7 years for a 5 kWp hybrid system with a battery. Panels carry a 25-year manufacturer warranty and a realistic 30+ year lifetime — after payback you get more than a decade of pure profit.
The current edition of the Polish solar subsidy program (in force in 2026) is the main grant scheme for prosumers. Key amounts for a new installation:
There is also a thermal-modernization tax relief in personal income tax — you can deduct the net cost of the installation (up to 53,000 PLN in total) from your taxable base across the next six years. The effect: an additional 12–19% return, depending on your tax bracket.
In practice, combined grants for a 5 kWp system with a 10 kWh battery reach 22,000 PLN (4,900 EUR) — the real net cost drops to about 5,100 EUR.
If you plan PV from day one, order the home with a pre-installed cable route from the roof cavity to the switchboard and a place for the battery in the utility area. That is an extra 200–400 EUR at the factory stage, but it saves 800–1,200 EUR on later retrofitting.
It is also worth coordinating the foundation with the meter box — a topic we covered in Foundations for a modular home. A 3-phase connection (11 kW+) is required for a heat pump and a fast EV charger — if you're thinking about an electric car within five years, size the system to 8 kWp with a 3-phase inverter from the start.
Solar for a year-round modular home in Poland in 2026 is an investment that pays back in 6–10 years, depending on the configuration. The sweet spot for a 38 m² home: 5–6 kWp with a 10 kWh battery, net cost after grants around 5,000–5,500 EUR, annual savings 950–1,100 EUR, self-consumption 75–85%.
A flat roof needs a ballast system and a load-capacity check — our models are engineered with headroom for exactly this. Before you order PV, agree with the home manufacturer on the inverter location, battery position and cable route. The MP Modular team helps coordinate the design with the PV installer — together with the heat pump we covered in Heating in a modular home.
We'll design the full package with you: home + heat pump + PV + battery. One team, one delivery date.
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