Never compare solar quotes by the bottom-line total; instead, work through three steps: first, check that all services are included (scaffolding, electrical work, registrations); second, calculate the price per kWp as the comparison metric; third, lay components and warranties side by side. Only once all three levels line up does the price tell you anything.
Key points in brief
- Two quotes with the same bottom-line total can contain completely different services.
- Price per kWp makes offers of different sizes comparable – but only for the same scope of services.
- "Brand-name module" without a model designation isn't information, it's an evasion.
- The cheapest quote often wins because line items are missing that later show up on the final invoice.
- Three comparable quotes are entirely sufficient.
Step 1: Is the quote complete?
Before comparing prices, clarify the scope. These items belong in a complete quote – check them off:
| Item | Must be included | Typical gap |
|---|---|---|
| Modules | Manufacturer, model, quantity, output (Wp) | "Brand-name module 440 Wp" without a model |
| Inverter | Manufacturer, model, output | just "incl. inverter" |
| Substructure | system, mounting method | often missing entirely |
| Scaffolding | its own line item with an amount | "by others" in the fine print – meaning: you pay separately |
| Electrical work | AC installation, meter position, any adjustments | "electrical on a time-and-materials basis" with no cost cap |
| Registrations | Grid connection application, notification procedure, Pronovo application | "administration by the client" |
| Acceptance & inspection | commissioning, safety certificate | missing |
| Documentation & handover briefing | system documentation, monitoring setup | missing |
| VAT | shown | "excl. VAT" in small print |
If a line item says "by others", "time-and-materials", or nothing at all, the quote isn't cheaper at that point – it's incomplete. Ask for a binding amount, or at least a cost cap.
Step 2: The fair price comparison per kWp
Comparing bottom-line totals is misleading as soon as the systems are different sizes. The calculation is simple:
Total price (incl. VAT, for the same scope of services) ÷ installed capacity in kWp = price per kWp
An example: quote A asks CHF 24,800 for 10.2 kWp (CHF 2,431/kWp), quote B CHF 22,900 for 8.8 kWp (CHF 2,602/kWp). The "cheaper" quote B is actually more expensive per kilowatt – and delivers less electricity on top of that.
The guideline values in the cost guide show where your result falls. If a quote sits noticeably below the market band, that's not a stroke of luck but a reason to check: what's missing? The typical patterns: Why quotes differ so much.
Step 3: Lay components and warranties side by side
Same price doesn't mean the same system. Three levels of comparison:
Modules: google the model designation – data sheet, product warranty (years), performance warranty. Between solid standard modules the differences are small; between standard and premium, real money is at stake. What matters is that you know what you're paying for. For guidance: The best solar modules.
Inverter: here the gap widens more than with the module – monitoring quality, battery expandability, service in a warranty case. A hybrid inverter in the quote is a plus if a battery could ever become a topic. The comparison: Inverters compared.
Warranties and service: who handles a warranty case – the local company or "the manufacturer"? Is there a fault service? Does the works contract have a payment schedule that follows progress (no large upfront payments)? The details: Works contract, payment schedule & warranties.
The comparison table to fill in
This is what the kitchen-table comparison looks like – one row per criterion, one column per quote:
| Criterion | Quote A | Quote B | Quote C |
|---|---|---|---|
| Output (kWp) | |||
| Final price incl. VAT | |||
| Price per kWp | |||
| Scaffolding included? | |||
| Electrical work flat rate or time-and-materials? | |||
| Registrations (utility/municipality/Pronovo)? | |||
| Module (type, warranty) | |||
| Inverter (type, hybrid?) | |||
| Completion date | |||
| Payment schedule | |||
| References in the region |
Tip: send all providers the same key data (consumption, plans for a heat pump/EV, battery preference) – otherwise you're comparing planning assumptions rather than offers.
The same table is available as a fillable PDF checklist with 18 check points, three quotes side by side and a quick scan for warning signs: Download the quote comparison checklist – free, no sign-up.
Five questions that resolve any ambiguity
1. "What is not included in this line item?" 2. "Who submits the Pronovo application – you or us?" 3. "What happens if the electrical work turns out more involved than planned?" 4. "Who do I call in five years if the inverter reports a fault?" 5. "Can you give me two reference systems in the region?"
Reputable providers answer all five without hesitation. Evasive answers are a signal – more on that in the article Red flags in solar quotes.
When clients bring us third-party quotes to review, we almost never find the differences in the module price – but in three inconspicuous lines: scaffolding "by others", electrical "time-and-materials", administration "by the client". Together these quickly add up to several thousand francs that stay invisible in the quote comparison and show up on the final invoice. Our advice: check these three lines first, then look at the price.
Frequently asked questions
How many quotes should I get?
Two to three, from companies that install themselves. More quotes rarely bring new insight but cost everyone involved time – including you.
Is the cheapest quote automatically bad?
No – but it deserves the closest scrutiny. Often it's cheap because services are missing or components aren't specified. If it's complete and cleanly specified, there's nothing against it.
Am I allowed to show a quote to a different provider?
That's entirely up to you. It's fairer and more productive to give all providers the same requirements and compare the results yourself – haggling down the price by showing competitors' quotes rarely produces a better system, just a thinner scope.
How long is a quote valid?
Usually 30 to 90 days; the period is stated in the quote. Material prices move – an expired quote gets recalculated, not simply extended.
What is a cost cap?
A binding upper limit for line items billed on a time-and-materials basis (typically: electrical work in an older building). This keeps a time-and-materials item calculable.
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At ecoEn, scaffolding, electrical work and all registrations are itemised – compare line by line. Free of charge and without obligation.
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Swissolar (industry recommendations), EnergieSchweiz.
Last updated: 9 July 2026 · Author: ecoEn editorial team
