Before you request quotes, you often want a first impression: How much electricity could my roof generate, what does the system cost approximately, and how large should a battery storage be? Much of this can be estimated online. This page shows which values can be calculated reliably, what information you need for this – and where the limits of online calculators lie.
Key points at a glance
The key points of this section can be summarised compactly:
- Online calculators provide a good initial orientation regarding yield, costs and storage size.
- A reliable calculation requires details on location, roof, consumption and future consumers.
- The solar calculator from EnergieSchweiz is considered a reliable initial assessment.
- A calculator does not replace a quote: scaffolding, roof condition, electrical distribution, and grid connection are project-specific.
- The best approach: calculate first, then compare individual quotes.
An online calculation provides good initial guidance but does not replace an inspection of the roof, electrical distribution and grid connection.
- As of 13.07.2026
What can be calculated online?
An online calculator can be used to estimate values such as the expected annual yield, the approximate system size, a rough cost range and an initial battery storage dimensioning. These values are guidelines – useful for orientation, but not binding. The more precise your inputs, the more useful the result.
What information is required?
For a useful calculation, the calculator primarily needs data on location, roof and consumption:
| Input | Why it matters |
|---|---|
| Address / Location | Determines irradiation and local conditions |
| Roof area | Basis for the possible system size |
| Orientation | South, east or west orientation affects the yield |
| Tilt | Affects solar irradiance |
| Shading | Trees, chimneys, and neighboring buildings reduce yield |
| Power consumption | Basis for self-consumption and sizing |
| Heat pump / electric car | Increase consumption and potential self-consumption |
The more precise these details are, the more realistic the estimates for yield, system size and self-consumption become.
How can the yield of a solar system be calculated?
The yield depends primarily on location, roof area, orientation, tilt, and shading. A calculator combines these details with irradiance and weather data to estimate the annual electricity production. The solar calculator from EnergieSchweiz uses this basis – including address, roof geometry, weather data, and assumptions about consumption and tariffs – to provide a location-specific initial assessment for your roof.
How can the costs of a solar system be calculated?
A rough cost range can be derived from the system size and equipment. However, because scaffolding, electrical work, storage capacity, and component selection vary greatly, this remains an approximation. You can read how the costs are broken down in detail on the page What does a solar system for a single-family home cost.
How can the storage size be calculated?
The sensible size of the battery storage depends on the consumption profile: from the daily pattern, the share of evening and night consumption as well as from the heat pump and electric car. A calculator provides a starting value; the appropriate dimensioning only emerges in detail with your actual consumption data.
Wie lassen sich Eigenverbrauch und Einspeisung berechnen?
A calculator also estimates what proportion of the solar power is expected to be consumed on-site and what proportion will be fed into the grid. This is economically important because self-consumed electricity replaces more expensive grid electricity, whereas the feed-in remuneration is lower. You can read how the remuneration works on the page Feed-in remuneration in Switzerland.
Where are the limits of online calculators?
The differences between a calculator and a specialist quote are particularly evident in project-specific points:
| Aspect | Online calculator | Specialist quote |
|---|---|---|
| Yield and size | Good estimate | Specifically, based on a site visit |
| Costs | Rough range | Binding positions |
| Roof condition, statics | Not recorded | Assessed on site |
| Electrical distribution, grid connection | Not recorded | Verified |
| Result | Guideline value | Basis for the order |
That is why the calculator is a starting point, not the basis for placing the order.
Why is a specialist quote more accurate?
A calculator only knows your roof from the data entered. It does not see the condition of the roofing, the electrical distribution, possible fire protection requirements or the situation at the grid connection. Yet it is precisely these points that determine feasibility and price. That is why the online calculation is a good first step – the reliable basis is provided by the on-site inspection.
solar-guide.ch recommends: Use an online calculator such as the Solar Calculator from EnergieSchweiz for initial orientation – but understand the result as a guideline, not as a binding figure. For reliable values, an on-site inspection and the comparison of individual quotes are required.
What errors frequently occur during calculation?
The following table assigns the most important points to Which errors frequently occur in the calculation?:
| Error | Consequence |
|---|---|
| Shading ignored | Yield is overestimated |
| Consumption estimated rather than measured | Design does not fit |
| Future consumers are forgotten | System later too small |
| Storage included as a flat rate | Over- or under-sizing |
| Calculator value understood as a fixed price | Disappointment with the quote |
These errors distort the estimate especially when a heat pump, electric car or battery storage is added later.
How does it go from the initial calculation to the quote?
After the initial estimate, these steps lead to comparable specialist quotes:
- Compile location and roof data as well as annual consumption.
- Use an online calculator to estimate yield, size and rough costs.
- Take future consumers (heat pump, electric car) into account.
- Submit a request and obtain individual quotes.
- Compare quotes and choose the right specialist installer.
This makes it easier to see quickly whether a quote is complete, comparable and plausibly structured.
Conclusion
A solar system can be well estimated online – in terms of yield, size, and rough cost range. However, reliable figures require an on-site inspection. The most sensible approach is the combination: first calculate, then compare individual quotes.
An online calculation is a good first step. For a reliable assessment, it is worth comparing individual quotes afterwards. With solar-guide.ch, you get free and non-binding contact with up to three suitable specialist installers in your region.
Request quotes free of charge and without obligation
Frequently asked questions and answers
How can I calculate a solar system?
With an online calculator that provides an initial assessment based on location, roof area, orientation, tilt, shading and consumption. The solar calculator from EnergieSchweiz is a good basis for this.
How much roof area do I need?
This depends on the desired output and your consumption. A calculator estimates the possible system size; the exact layout is determined on site.
How accurate are solar calculators?
They provide useful benchmarks, provided the inputs are correct. However, they do not account for roof condition, electrical distribution and grid connection – for that you need a specialist quote.
Can I calculate the battery storage size online?
You receive a starting value. The appropriate size depends on the consumption profile and is determined in detail using actual consumption data.
Why do I still need a quote?
Because scaffolding, roof condition, electrical distribution, fire protection, grid connection and component selection are project-specific. These points determine feasibility and price and cannot be conclusively clarified online.
Average: 5 out of 5 stars (1 rating)
