How we calculate
your savings.

We sell nothing. We do not make panels, batteries or inverters, and we are not paid more for recommending a bigger system. That independence shapes how we built this model around three rules.

• Be conservative. Where a number could reasonably be high or low, we lean towards the cautious end, so a real quote is more likely to beat our estimate than to disappoint it.
• Use public data. Every constant below traces back to a named, independent source: installers' published price guides, the Danish regulator, the Danish Energy Agency, Statistics Denmark and utilities. All are linked in the final section.
• Show the seams. An estimate made in sixty seconds from a few questions cannot replace a site survey. The 'Limits' section is an honest list of what the model simplifies.

Solar only saves you money in two ways: the power you make and use yourself (so you don't buy it), and the surplus you send back to the grid (which you're paid a little for). Everything else is detail. The yearly saving from a solar system is therefore:

A battery doesn't make any power of its own. What it does is move energy through time, storing your midday surplus, or cheap night-time grid power, for the expensive evening peak. In the model that shows up as a much larger self-used share, not a separate income line. For a battery on its own, the value instead comes from trading the price difference across the day, which we treat as a flat yearly figure per kWh of storage.

The system is sized to your home first, and the cost, savings, home-value and CO2 numbers all follow from that single size.

We keep the questionnaire short on purpose. Each input changes the answer in a way a real installer would recognise:

• People in the home. Drives your baseline electricity use: lighting, appliances, hot water, screens. More people, more kWh.
• How you heat. The single biggest lever. A heat pump or electric heating can double or triple a home's electricity use, which changes both the right system size and the savings.
• Roof type. Doesn't change how much you save, but it changes what the install costs. A flat or fibre-cement roof needs more work than tiles.
• Electric car. Adds a large, predictable block of consumption that solar is very good at covering. We size this from your daily distance.
• Your own kWh figure. If you know your yearly consumption from a bill, you can type it in and it overrides our estimate entirely.

Baseline household electricity (before heating and the car) is estimated as 1,500 kWh fixed, plus 1,100 kWh per adult and 450 kWh per child. For two adults that is about 3,700 kWh a year, in line with the 3,700 to 4,500 kWh the Danish Energy Agency and Bolius report for a typical family home without electric heating.

Danish installers publish remarkably consistent price guides. A typical 6 kWp rooftop array runs about 95,000 kr installed (roughly 15,800 kr per kWp), per GreenMatch and Elberegner. Add a battery and the combined job is around 125,000 kr. A home battery on its own runs about 5,000 to 9,000 kr per kWh, so a typical 10 kWh unit is roughly 45,000 to 75,000 kr installed, per Byggeli, Tømrerne and solceller.nu.

Rather than hard-code a handful of fixed prices, the model builds cost up from the size it picks for your home, using per-unit rates derived from those guides:

So a 4 kWp array works out near €8,400 (≈ 63,000 kr) and a 9 kWp array near €18,900, the same band the installer guides quote. Prices exclude the Danish håndværkerfradrag and any subsidy, which only make the real figure lower.

The retail price is what makes self-used solar valuable: every kWh you generate and use is a kWh you don't buy at the full rate. Across 2025 the average Danish household paid about 2.3 to 2.6 kr per kWh all-in, energy, grid, taxes and VAT, according to Forsyningstilsynet (the regulator), findenergi.dk and Green Power Denmark.

We use €0.33 per kWh (≈ 2.5 kr) for power you buy, and €0.07 per kWh (≈ 0.5 kr) for surplus you export. Exported power earns roughly the spot price, far below the retail rate, which is exactly why a battery that lets you keep more of your own power is worth so much.

One caveat worth knowing: from 1 January 2026 the Danish electricity tax falls towards the EU minimum (per Bolius), which pulls the retail price down, while rising network and spot prices push it back up. We keep 2.5 kr as a steady, middle-of-the-road figure and will revisit it as the year settles.

A solar panel in Denmark produces roughly 950 kWh per kWp per year on a reasonable roof, a widely used planning figure for the Danish latitude and climate. So a 6 kWp array makes around 5,700 kWh a year.

But you can't use all of it as it's made. The sun is strongest at midday when nobody's home. The share you use directly is the self-consumption rate, and it is the difference between a good and a mediocre investment:

Doubling self-consumption with a battery is why the savings jump so much when you add storage, even though the panels make exactly the same amount of energy. For a battery with no panels, there is nothing to self-consume, so we model its value as a flat €40 per kWh of storage per year (≈ 300 kr) earned by charging cheap and discharging at peak, a deliberately cautious figure.

This is the input most calculators ignore and the one that matters most. How you heat your home decides how much electricity you use, and a home that heats with electricity has far more for solar to offset.

A typical air-to-water heat pump in a Danish house uses about 4,000 to 7,000 kWh a year on top of normal consumption, per NRGi, Andel Energi and Elberegner. Direct electric heating uses far more again. Statistics Denmark finds electrically heated homes use about 3.2× the electricity of district-heated ones. So we add a fixed block to consumption based on your answer:

Because we size the array to your consumption, a heat-pump home gets a bigger system and a higher self-consumption base, so its yearly saving can be roughly double that of an otherwise identical district-heated home.

Your roof doesn't change how much sun you catch, but it changes how much the fitting costs. Tile and standing-seam steel are the straightforward case. A flat roof needs ballasted or angled mounting frames, and fibre-cement (eternit) or slate needs extra care and sometimes specialist handling. Danish roofing guides such as Solcellepriser and Tømrerne describe the difference. We apply a simple multiplier to the install cost:

The multiplier only moves the price, never the energy or the savings, so it changes your payback time rather than your yearly benefit.

Solar is also a home improvement, and buyers pay for it. The widely cited Zillow analysis found homes with solar sold for about 4.1% more, and European property studies put the uplift at roughly half to all of the panels' installed cost. We take the cautious middle of that:

We base it on the cost of the panels, not the battery or charger, because the resale evidence is about solar specifically. A battery with no panels is credited a small token amount. This figure is the softest number on the site: it depends on your local market and the buyer in front of you, so treat it as directional, not a valuation.

Every kWh your panels generate is a kWh the grid doesn't have to. We multiply your yearly production by 0.15 kg CO2 per kWh, a conservative figure for the increasingly wind-and-solar Danish grid mix. A 6 kWp array making 5,700 kWh therefore avoids roughly 850 kg of CO2 a year. We don't count the emissions embodied in making the hardware, which a few years of generation repay.

Two adults, district heating, a tile roof, no electric car, choosing solar + battery. Here is every step the model takes:

Switch the heating answer to heat pump and consumption climbs to 8,700 kWh, the array grows to about 9 kWp, and the yearly saving more than doubles to roughly €2,400 (≈ 18,000 kr), the clearest illustration of why we ask how you heat.

An estimate is not a quote. Specifically, the model:

• Assumes a roof with reasonable orientation and little shade. A north-facing or shaded roof produces less; a perfect south-facing one produces more.
• Uses one national price for electricity. Your tariff, supplier and whether you're on a spot or fixed plan all shift the result.
• Sizes the array to your consumption between 3 and 12 kWp. Your usable roof area may cap it lower, or allow more.
• Treats self-consumption as a single rate. In reality it depends on when you use power and how your battery is controlled.
• Excludes subsidies, grants and tax deductions, all of which make the real economics better, not worse.
• Gives a home-value figure that is directional only and varies by local market.

The honest summary: our estimate is a well-grounded starting point for a conversation, built to be beaten by a real quote rather than to flatter. Always get one or more quotes from vetted local installers before deciding.

Every figure above traces to one of these. They are independent installer guides, the Danish regulator, the Danish Energy Agency, Statistics Denmark and utilities, not our own claims.

• GreenMatch: solar prices
• GreenMatch: 6 kW solar + battery
• Elberegner: 6 kW system
• Byggeli: home battery prices
• Tømrerne: home battery prices
• solceller.nu: battery cost & payback
• Forsyningstilsynet: electricity prices
• findenergi.dk: what a kWh costs
• Green Power Denmark: 2025 electricity bill
• Bolius: 2026 electricity-tax cut
• NRGi: heat-pump consumption
• Andel Energi: heat-pump yearly use
• Elberegner: heat-pump electricity use
• Bolius: average family consumption
• Statistics Denmark: household electricity use
• Solcellepriser: roof types & mounting
• Tømrerne: solar on the roof
• Zillow: solar and home sale prices