A reference is meaningful when it's specific, regional and a few years old – and when you can talk to the customer behind it. Ask for two to three nameable systems in your area, ask the reference customer five targeted questions, and read online reviews for patterns instead of stars. One hour of effort that can decide twenty years of system operation. (As of: July 2026)
Key points in brief
- Photos and star ratings are just scenery – a reference only becomes verifiable with a location, system type and a customer who can be reached.
- The most valuable references are a few years old: they show not just the installation, but whether the service afterwards worked.
- Five questions to a reference customer are enough: deadlines, the construction site, supplementary bills, yield, reachability in case of a fault.
- Online reviews are read for patterns: distribution over time, the content of critical voices, the company's response.
- No nameable references are a warning sign – few references at a young company aren't necessarily one.
Why references reveal more than any brochure
Modules, inverter, warranty promises: on paper, solar providers differ surprisingly little. The hardware often comes from the same manufacturers, and anyone can print good return charts. What actually differs is the work – depth of planning, cleanliness of installation, reliability after acceptance. And for exactly that, there's only one honest piece of evidence: systems that were built, and customers who talk about them.
References are therefore not a politeness topic for the end of the conversation. Alongside the quote itself, they're the most important checking instrument you have as a layperson – precisely because you don't have to judge the technical quality of a design yourself. A company that has been building in your region for years leaves traces. The only question is whether you have them shown to you.
Which references are meaningful?
Not every reference is worth the same. Three characteristics make the difference:
Regional. You can go and look at a system two villages over, but not a «reference» at the other end of Switzerland. Regional references also prove that the company knows the local grid operators, building authorities and notification channels – a point that saves more time in day-to-day project work than you'd think.
Comparable. A single-family home with a pitched roof says little about competence for an in-roof solution or a flat-roof commercial project. Ask for systems that resemble your situation: roof shape, approximate size, possibly storage or a wallbox on top.
Matured. This is the most underestimated point. A freshly installed system always shines. Whether the company still picks up the phone in year three when the inverter reports a fault is only shown by a reference with a few years of operation. So deliberately mix it up: a young system for the current way of working, an older one for the service afterwards.
How do you get hold of real references?
The simplest way is asking directly in the consultation: «Can you name two or three systems in the region for me – and could I briefly speak with a customer?»
Don't expect an immediate list of names here – quite the opposite. A reputable company doesn't hand out customer data without checking first – it has to ask the reference customers for their consent first, and from experience that takes a day or two. This small delay is a good sign, not an excuse. It only becomes an excuse when nothing concrete has come after the second follow-up.
Besides that, two checking paths are worthwhile that work without the provider's help:
- Look at systems. Many references can be viewed from the street. Look for straight rows of modules, clean edge clearances, and neatly routed cables on the façade – details you can recognise even without technical knowledge.
- Check the company history. Commercial register entry, registered office, how long it's existed: we've described this basic check in the guide on warning signs of disreputable providers. References complement it, but don't replace it.
What do you ask a reference customer?
If a conversation comes about, you don't need half an hour. Five questions cover the essentials – and for each one there's something specific to listen for:
| Question for the reference customer | What to listen for |
|---|---|
| Were deadlines and the construction time kept? | Delays happen – what matters is whether they were communicated |
| What did the construction site look like – during and after installation? | Care on the roof almost always shows on the ground too |
| Were there supplementary bills compared with the quote – and were they justified? | A cleanly justified supplementary bill is normal, a «surprising» one isn't |
| Does the system deliver roughly what was forecast? | A rough estimate is enough – nobody expects it down to the exact kilowatt-hour |
| Has there been a service case since – and how quickly was there a response? | The most important question of all; «no case so far» is also an answer |
These questions don't replace a technical review of the quote – the minimum technical specifications exist as the yardstick for that.
Listen to the tone too. Reference customers are naturally selected to be favourable – it gets interesting in the side remarks. «In the end it did go quickly» or «it worked on the second call» says more than any overall rating.
How do you read online reviews correctly?
Google reviews and comparison portals are the most convenient checking path – and the easiest to manipulate. Counting stars therefore doesn't bring much. Reading patterns does:
Distribution over time. Organically grown review profiles develop over years, at irregular intervals. A wave of five-star reviews within a few weeks – possibly all from profiles with no further activity – is a well-known pattern of bought or organised reviews.
The content of the critical voices. Every company that really operates has one or two bad reviews; a flawless profile is more suspicious than reassuring. Read the critical entries carefully: are they about matters of taste and misunderstandings – or does a pattern like «unreachable after payment» repeat? Repetition is the signal, not the individual case.
The company's response. If the company responds to criticism factually and with a focus on solutions, that speaks for its service culture. Snarky replies or silence on legitimate points are a preview of what awaits you in a warranty case.
In short: reviews are a pre-filter, not a basis for a decision. They don't replace the conversation with a real reference customer.
What if a provider can't name any references?
An honest distinction is worthwhile here – because not every thin reference list means the same thing.
The established company with no nameable references is a genuine warning sign. Anyone who supposedly builds «hundreds of systems» for years but can't show a single one specifically, or only points to stock photos and anonymised «project examples», either hasn't built what they claim – or has customers who aren't well disposed towards them. Either disqualifies them. This category also includes the kitchen-table sales pitch that responds to the reference question with time pressure: you'll recognise the pattern from the red flags.
The young company with few references is a different case. Every solar company once started with its first system, and a two-year-old company with five clean, visitable references can be the better choice than a large sales operation with a glossy folder. Check the background of the key people instead here: who installed and designed where before? Craft experience is tied to people, not to the company's founding date. This also includes a look at the payment plan and contract – with a young company, a fair contract structure counts double.
What isn't an excuse for any company, however: data protection as a blanket answer. It's true that customer data may only be passed on with consent. It's false that nothing at all could be shown because of this – systems from outside, references with obtained consent, and documented projects exist at every company that has some.
The reference question is one of the moments in a consultation that we value most – even though it creates work for us. Because yes: we first ask our customers whether they'd like to be contacted, and that costs a day or two each time. But the conversations that result afterwards do half our consulting work for us. Anyone who has spoken to someone we installed for three years ago asks differently: no longer «whether», but «how». And one more observation from the region: the most revealing reference visits aren't the most beautiful roofs, but the ones with a story – a supplementary bill because of crumbling tiles, an inverter swap in year two. That something happened doesn't distinguish a company. How it dealt with it does.
Frequently asked questions
How many references should a solar company be able to name?
Two to three specific, regional systems are enough – quality beats quantity. More important than the number is the mix: a current system for the way of working today, an older one for the service after installation. Long anonymous project lists with no contact person, on the other hand, are worth little.
Can a solar company just give me customer names and addresses?
No – passing it on requires the consent of the customers concerned. Reputable companies obtain this consent on request, which can take a day or two. You should only become suspicious when, despite asking, nothing concrete ever comes.
Can I visit a reference system?
Often yes – many systems are visible from the street, and some reference customers are also happy to show their installation on request. During the visit, look for straight rows of modules, clean cable routing, and tidy finishes; these are the details that even laypeople can recognise.
Are reviews on comparison portals more reliable than Google reviews?
Not fundamentally – both can be influenced, for example by selectively inviting satisfied customers. Read for the same patterns on all platforms: distribution over time, the substance of critical voices, the company's response. A portal seal doesn't replace any of these checks.
What should you make of reference photos on the website?
Photos are a starting point, but not proof – check whether they belong to nameable, regional projects. Interchangeable images with no location or context could come from any image database. Feel free to ask directly in the conversation: «Which of these systems is near me?»
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Ask us for references.
We're happy to name systems from your region for you – with the customers' consent, as it should be. And we'll answer any question about your own situation before or after that.
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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 ecoEn GmbH's consulting and installation practice, Zurich region; Commercial Register of the Canton of Zurich / zefix.ch (company verification).
Last updated: 9 July 2026 · Author: ecoEn editorial team
