The research swiss solar calculator, solar calculator and estimation of the solar price in Switzerland show a very specific intention: you want an estimate before speaking to an installer. It's healthy. An owner should not sign a project costing CHF 20 000 or 35 000 without understanding the orders of magnitude. But a calculator can also misleading if he hides his assumptions. This guide explains how to use a calculator as a tool purchase, not like a crystal ball.
1. What a good solar calculator should estimate
A good Swiss solar calculator must produce at least five results: the recommended power in kWp, the annual production in kWh, the gross cost, the net cost after aid and the annual saving. If the tool does not give like a global amount or a message like "request a quote", it doesn't really help you buy. He simply becomes a contact form. Conversely, a useful calculator should allow you to understand why an 8 kWp roof can be more relevant than a 12 kWp roof, or why a battery can be interesting in one case and useless in another.
Switzerland adds a particular complexity: the electricity purchase price, the electricity recovery price surplus, aid, tax practices and deadlines vary depending on the municipality, the canton and the network manager. A national calculator must therefore remain cautious. It can give you a basis of decision, but the local estimate must confirm the figures.
Power
kWp proposed according to surface area, orientation, shading and future consumption.
Production
annual and monthly kWh, with shading and orientation losses.
Price
Gross budget, cost per kWp, options and net cost after aid.
Profitability
Self-consumption, injection, annual savings and return on investment.
2. Data to enter to avoid a bad estimate
The quality of the result depends on the quality of the inputs. Your address is used to estimate the sun, altitude, the roof and sometimes local rates. Your annual consumption, in kWh, gives the size of the need. The type of heating greatly changes the calculation: a house heated with oil with 4 500 kWh of electricity per year does not have the same profile as a house with a heat pump and 9 000 kWh of total consumption. A car Electric can add 2 000 to 4 000 kWh per year depending on mileage. A controllable boiler can absorb surplus during the day. All of these uses change the value of the same panel.
Before using a calculator, take your last annual bill. Note the consumption, the price full kWh, fixed costs, supplier or GRD, and if possible day/night distribution. Add your future projects: heat pump, terminal, battery, renovation, expansion, teleworking. Finally, look at your roof without excessive optimism: chimneys, skylights, trees, mountains, neighboring buildings and snow can count.
3. How to read the price given by a solar calculator
The price of a solar installation is not just the price of the panels. The modules represent only part of the cost. You also pay for the inverter, the rails, the hooks, the scaffolding, the security, the labor, cabling, protections, switchboard, controls, administrative procedures and company margin. This is why a reduction in the price of modules does not automatically translate into an identical reduction in the estimate.
| Calculator output | What this means | Question to ask in the quote |
|---|---|---|
| CHF/kWp | Standardized installation price | Is everything included? |
| Production kWh/year | Estimated annual volume | What production month by month? |
| Self-consumption | Share consumed on site | On what habits? |
| ROI | Estimated return | With what future price? |
4. Net price: subsidies, taxation and cash flow
A calculator should distinguish between the gross price and the net price. The gross price is what the company charges. The estimated net price removes aid and the tax effect. But be careful: help is not always available at the same time as the invoice. You may need to pay for part of the project before receiving Pronovo or before benefiting from the tax effect. For a buyer, profitability is therefore not just a question mathematical; it’s also a question of cash flow.
If a calculator shows a very low net cost, ask what support it assumes. Pronovo? Help cantonal? Municipal aid? Tax deduction? VAT? Battery bonus? Some aid cannot be combined, some are limited, some depend on the request date. A serious installer does not sell a help like unconditional certainty; he explains how to secure it.
5. Profitability: why self-consumption is worth more than injection
The profitability calculation is based on a simple idea: a self-consumed kWh avoids the purchase of a full kWh network, while an injected kWh is remunerated according to the local recovery tariff. These two values are not identical. This is why a perfectly profitable installation is not necessarily the installation that covers the entire surface of the roof. It is the one that produces a lot of useful kWh.
A household absent all day without a battery consumes less than a household working from home or equipped with a controllable heat pump. An electric car recharged at midday can transform low-paid surplus in direct economy. A smart boiler can do the same thing with hot water. The role of the calculator is therefore to test scenarios: without battery, with battery, with future PAC, with EV, with manager of energy. If the tool does not allow these variations, keep its results as a first approximation.
6. Transform the result into specifications for installers
The best use of a calculator is to prepare specifications. You can send to installers your consumption, your power estimate, your future projects and your expectations. Ask then it is up to each company to confirm or correct the hypotheses. If the calculator suggests 10 kWp and the installer suggests 14 kWp, this is not necessarily bad. But he must explain why: future pump heat, better economy of scale, very favorable roof, acceptable injection price, or desire for cover a charging station.
Conversely, if an installer offers less than the calculator, he must also explain it: shading, poor orientation, safety constraints, limited electrical panel, budget, or low consumption in day. The calculator then becomes a dialogue tool. You don't buy his figure; you buy the ability of the installer to justify a better figure.
7. Checklist before requesting a quote
- Exact address and roof photos, if possible from several angles.
- Annual consumption in kWh and recent bill.
- Full electricity rate and surplus recovery rate if known.
- Heat pump, battery, terminal or expansion project in the 5 years.
- Preference: minimum price, autonomy, aesthetics, preparation for battery or emergency power.
- Question about aid: who submits the Pronovo file, when and with what documents?
7 errors that distort a solar calculator
A result accurate to the nearest cent is not necessarily a reliable result. Before sending an estimate to an installer, look for these seven common mistakes:
- Confusing public potential and real implementation. A map does not always see the recesses, security, condition of the roof or cable routing.
- Use only an annual average. Ask for monthly production and shading assumption: winter, skylights and snow change the curve.
- Deduct aid twice. Pronovo, local aid and tax effect must be displayed separately, with their condition and timing.
- Treat each kWh as equivalent. A self-consumed kWh, an injected kWh and a kWh lost through capping do not have the same value.
- Copy a national tariff into a local simulation. The DSO, the municipality, the fixed costs and the takeover contract must be identified.
- Assume a battery is free in the calculation. Add losses, power, replacement, warranty and option price; Also test the scenario without battery.
- Do not date the result. Record assumptions, calculation version and sources, then double-check support and pricing before ordering.
For federal aid, compare the calculator's assumption with the Official price of Pronovo. It remains indicative: your quote must confirm the power, the date of commissioning and the category of the installation.
Go from calculator to real quote
Use the estimate as a basis, then compare offers on the assumptions: power, production, aids, materials, guarantees and deadlines.
Callback request
Decision framework
A verifiable decision, not an isolated estimate
Before comparing solutions, clarify the project assumptions, their sources and dates, and the responsibilities involved. Use your bill, roof plan and written responses to check that each quote covers the same needs.
Start with a measurable question
Start your solar decision with building data. Record the address, building type, relevant area, energy use and desired result. When assessing price, generation and quote estimates from a solar calculator, distinguish readings, written confirmations and assumptions. Compare gross and net amounts for the same scope; separate installed capacity from annual generation. Check grant conditions before deducting support from the budget. Prepare open questions for the installer, municipality, grid operator and insurer, identifying the record or measurement needed to answer each one.
Turn your bills into scenarios
Gather twelve months of bills if possible. Separate energy, network use, metering, taxes, levies and optional services. Include heating, hot water, EV charging and absences. An annual average can hide demand concentrated in mornings, evenings or winter. Compare conservative, central and favourable scenarios for a buyer who wants to understand the assumptions before requesting three offers. Keep units, scope and tariff dates consistent so that differences reflect the options being compared.
Check the roof and surroundings
Orientation, slope, chimneys, dormers, trees, antennas, snow, access, ventilation and neighbouring buildings affect solar generation. Ask for an aerial image, a dimensioned roof plan and a seasonal shading assessment. Have the roof covering, possible asbestos, structural capacity and cable routes assessed before committing to system capacity. A simulation for price, generation and quote estimates from a solar calculator should explain losses, show monthly generation and account for roof renovation or expansion before installation.
Compare quotes for the same scope
Three quotes are comparable only when they cover the same scope. Ask for the brand and exact model of each module, inverter, battery, protective device and mounting system. List scaffolding, distribution-board upgrades, grid connection, metering, applications, monitoring, maintenance, VAT and options separately. A lower price may exclude a service; a higher price may include a structural assessment or broader service terms. Identify who coordinates with the DSO and provides commissioning documents.
Check warranties and responsibilities
Product, performance and installation warranties, and insurance, cover different matters. Check duration, exclusions, beneficiary, claims procedure, response times and service arrangements if a manufacturer changes distributor. Keep invoices, serial numbers, photos, certificates, diagrams and handover records. The owner should retain access to the file documenting the address, roof, consumption, tariff, Pronovo calculation and quote exclusions, even if the installer or project manager changes. Identify who addresses sizing errors, water ingress, communication faults or substantial differences between simulated and measured generation.
Compare the full cost
Include purchase, installation, applications, maintenance, remaining grid purchases, inverter replacement, possible roof work and surplus revenue. For a battery, consider usable capacity, losses, cycles, backup reserve, temperature, software and replacement. For a contract, check subscriptions, price changes, credit validity and exit terms. For a grant, consider eligibility and payment timing. Test whether the decision remains affordable if feed-in tariffs fall, consumption changes or the project is delayed.
Prepare for commissioning and handover
Before work starts, request a list of tests and documents to be provided. These may include insulation measurements, protective-device checks, grid settings, backup settings, connector checks, circuit labels, monitoring access and meter readings. An app displaying data does not replace a complete technical handover. Ask for safe shutdown instructions, a service contact and the circuit diagram. A dated handover record supports warranty claims and comparisons between expected and measured generation, bills and consumption.
Plan for future electricity use
A heat pump, water heater, EV, home working, extension, tenant change or renovation can alter a home’s electricity use. Include planned changes in the simulation. Check whether the inverter, distribution board, communications, available space and grid connection allow realistic expansion. An open system can be more useful than a larger system with limited compatibility. For a buyer who wants to understand the assumptions before requesting three offers, assess how to avoid a second costly installation when needs change.
Keep the evidence organised
Keep annotated bills, plans, simulations, compared quotes, grant conditions, official applications, before-and-after photos, certificates, warranties and generation records in one file. Date each item because tariffs and programmes change. An undated screenshot cannot establish a contractual condition. Record the amount stated, the condition that applied and the person responsible. These records support budget checks, a future sale and discussions with the DSO, insurer or authorities.
Check the quote before signing
Before signing, check the description, address, owner, capacity, models, generation estimate, exclusions, prices, VAT, grants, schedule, handover, warranties and termination. Gather the relevant records: the address, roof, consumption, tariff, Pronovo calculation and quote exclusions. Request written answers to unclear points and identify who will resolve them. Keep the final quote, data sheets and contract terms together. A promised saving or equipment brand cannot replace the scope of work, calculation assumptions and service arrangements.
Enter data that exists
A calculator gives accurate output even when the input is fragile. Use address, altitude, orientation, slope, actual available surface, obstacles, seasonal shading, coverage status and measured consumption. Indicate whether the area includes chimney, skylight, curb, path or safety distance. On the demand side, separate annual energy, simultaneous power, heating, hot water, mobility and periods of absence. In terms of price, distinguish between materials, assembly, scaffolding, switchboard, connection, procedures, VAT, maintenance and replacement. Record unit, date and source of each input so that an installer can reproduce or correct the scenario.
Test the hypotheses one by one
Vary orientation, inclination, shading, power, degradation, purchase price, trade-in price, inflation, self-consumption, battery, interest rate and commissioning date. Don't change five parameters between two scenarios: you will no longer know what explains the difference. Compare monthly production, kWh purchased, kWh injected, battery cycles, levelized cost, return time and safety margin. If PVsyst, Sonnendach or an installer tool gives different results, ask what weather data, losses, temperatures and network limits were used. The calculator is a preparation of a quote, not a guarantee of performance.
Convert the simulation into questions
Bring the scenario and its assumptions to three comparable offers. Ask for the module and inverter reference, the layout plan, DC and AC power, low, central and high production, surplus processing, aid, VAT and exclusions. Specify who is responsible for roofing, protection, metering, declaration, reception, monitoring and service. Check that the battery is compared on useful capacity and cycles, not on nominal capacity alone. A useful simulation also indicates what is not modeled: future work, breakdown, exceptional snow, price change, extension or resale. The signature must be on the written perimeter, not on the colored number on the screen.
Sensitivity check before decision
Make a final table with four columns: hypothesis, central value, conservative value and consequence. Add irradiance, albedo, temperature, efficiency, cabling, availability, degradation, replacement, interest, inflation, recovery price, nighttime consumption, breakdown and construction time. Circle the variables that are actually negotiable in the offer and gray out those that are only meteorological. If a small variation makes the return too long, do not mask the risk with a more optimistic figure: ask for a different power, a battery-free option or a renovation step. The calculator thus becomes a dialogue tool and not an automatic promise.
Use this section with your invoice, roof plan and quotes. The final decision must remain linked to the official conditions, the actual connection and the written contract.