A solar quote only becomes comparable once it contains twelve specifications in black and white – from the module and inverter type through the calculation basis for the yield to the question of whether scaffolding, AC work and all the registrations are included in the price. If one item is missing, you're not comparing two prices, but two different products. (As of: July 2026)
Key points in brief
- Comparing quotes rarely fails because of the price per kWp – it fails because quotes contain different things.
- Twelve specifications make a quote verifiable: components with type designation, sizing, the basis for the yield, scope of work, warranties, deadlines.
- «Brand-name modules» and «quality inverter» aren't specifications, but evasive manoeuvres – a red flag.
- The most inconspicuous items are the most expensive: scaffolding, meter-position adaptation, registrations.
- With our comparison checklist, you can check any quote in a quarter of an hour.
Why «price per kWp» alone is no good
Two quotes, the same roof size: provider A asks for CHF 24,000, provider B CHF 19,500. Clear-cut? Only once it's established that both deliver the same thing: B is missing the scaffolding (separate, «time and materials»), the meter-box adaptation («by others»), the Pronovo registration («we're happy to support you with that») – and the modules are a nameless line item. 19,500 quickly becomes 24,000 in reality, just without A's planning quality.
The only protection against this is a system: check every quote against the same list. We've described the comparison methodology separately – here comes the technical substance: what has to be in there.
The 12 minimum specifications
| # | Specification | How to recognise the quality |
|---|---|---|
| 1 | Modules: manufacturer, type, quantity, output (Wp) | type designation googleable; total kWp = quantity × Wp |
| 2 | Inverter: manufacturer, type, AC output | type stated; ratio to module output plausible (see #3) |
| 3 | Sizing: DC/AC ratio | moderate oversizing is normal and efficient – but it has to be stated, not hidden |
| 4 | Mounting system and roof-type suitability | system named; for flat roofs: ballasting/statics mentioned |
| 5 | Statics statement | Who assessed the load-bearing capacity – and when (site visit!)? |
| 6 | Yield forecast with basis | kWh/year WITH assumptions: location, orientation, tilt, shading – not just a bare figure |
| 7 | Electrical work on the AC side | Cable route, connection, meter position: included or excluded? Exclusions priced? |
| 8 | Scaffolding / fall protection | its own line item with an amount – not «by others», not «time and materials» |
| 9 | Registrations: grid operator connection request, Pronovo/EIV, GO, notification procedure, incentives | explicitly listed as an included service |
| 10 | Warranties broken down | the manufacturer's product vs. performance warranty vs. the company's installation warranty – three items, three periods |
| 11 | Monitoring/commissioning | Monitoring set up? Instruction given? Metering concept for a ZEV? |
| 12 | Deadlines and payment plan | target date for installation; partial payments tied to construction progress |
As of: July 2026. The list applies to typical roof systems on residential buildings; for a ZEV, in-roof or façade installation, further items are added.
The three items that most often cause trouble
The yield forecast with no assumptions (#6). «Approx. 9,500 kWh/year» can be honestly calculated or plucked out of thin air – the difference lies in the assumptions. A verifiable forecast states orientation, tilt and how shading is handled. Why this matters: every profitability promise is built on this figure. Anyone who cheats here cheats everywhere.
The scaffolding (#8). A four-figure item depending on the building – and the most popular place to make a quote look cheaper. «By others», translated, means: you organise and pay for it yourself, on top. An honest quote shows the scaffolding with an amount, even if that makes the comparison look «more expensive».
The registrations (#9). Connection request, Pronovo, GO, possibly municipal incentives and the notification procedure – together a few hours of specialist work that several thousand francs of your remuneration hang on. If it says «support with registrations» instead of «registrations included», ask who ultimately submits what – and who's liable if a deadline is missed.
How to use the list in practice
1. Lay both (or three) quotes side by side and tick off the twelve points – easiest with our downloadable checklist. 2. Missing points aren't knock-out criteria, but follow-up questions: reputable providers fill them in, others dodge – either is a result. 3. Only once all quotes reflect the same scope of work do you compare prices. Before that, you're comparing paper.
We see other providers' quotes every week that prospective clients bring us for comparison – and the pattern is consistent: the price difference between two quotes almost always shrinks dramatically once the scope of work is aligned. What comes across as «20 percent cheaper» turns into just five percent after adding scaffolding, meter work and administration – with thinner planning. The reverse is also true: sometimes the more expensive quote is simply over-equipped. That's exactly why we hand out the checklist openly, even at the risk of it being used against us: a quote that doesn't survive the twelve points isn't one we want to win with anyway.
Frequently asked questions
Does a quote really have to name the exact module types?
Yes. Without a type, you can check neither the datasheet nor the warranty terms nor the market price – and at delivery you can't verify whether what was quoted is what goes on the roof. «Equivalent substitute» is only verifiable with a defined reference.
What's a normal DC/AC ratio?
A moderate oversizing of the inverter is common and economically sensible – the peaks above the AC output only clip a small amount of annual yield. What matters isn't a specific value, but that the sizing is stated and justified.
Does a profitability calculation belong in the quote?
It's not a must, but common – what matters is its transparency: the electricity-price assumption, the actual grid operator's feed-in tariff, the self-consumption rate and incentives must be shown as assumptions, with a range instead of a point promise.
The quote refers to the terms and conditions – is that enough for warranties?
No. The breakdown (who guarantees what, for how long) belongs in the quote itself; the terms and conditions supplement transparency, but don't replace it.
What if the provider says nobody quotes in that much detail?
Then you have your answer. Any specialist company can deliver the twelve points – most do it unprompted.
Free initial consultation
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Every ecoEn quote contains the twelve points as standard – site visit included, assumptions disclosed, registrations in the price.
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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: Experience from installation practice; Swissolar (recommendations on quotes and performance warranties).
Last updated: 9 July 2026 · Author: ecoEn editorial team
