Most solar conversations are shaped by the installer, not the homeowner. The sales pitch is rehearsed; your questions are not. That imbalance is exactly why a short, structured list of questions is one of the most useful things you can bring to a quote meeting.
You do not need a perfect script or technical expertise. You need questions that force the installer to become specific - and that reveal how they behave when the conversation shifts from selling to explaining.
Why the same questions, asked of everyone
The easiest way to compare installers fairly is to ask each one the same questions and record the answers side by side. This does two things. It turns a sales conversation into a structured comparison, and it makes differences between installers visible - because a confident, well-run company tends to answer specific questions specifically, while a weaker one becomes vague exactly where detail matters.
A useful rule: if something still feels unclear after two direct questions on the same topic, treat that as a warning sign and ask for the answer in writing.
About the system
These questions establish what you are actually buying, beyond the headline price.
- What total system size are you proposing, in kWp, and why that size for my home?
- How many panels are included, and what is the wattage of each panel?
- What inverter make and model is included, and what is its standard warranty period?
- Are optimisers or micro-inverters included? If not, how will shading on my roof affect output?
- What monitoring system comes with the installation, and what will I be able to see on it?
Why it matters: two quotes can look similar on price while describing very different systems. A smaller array, a weaker inverter, or no shading mitigation can all hide behind a lower number.
About the installation
Solar quotes often assume things that later become extra costs. These questions surface them early.
- Who exactly will carry out the installation - your own engineers, or subcontractors?
- What assumptions have you made about scaffolding, roof access, and any electrical work?
- What happens if my roof condition causes unexpected work once the job starts?
- How long will the installation take, and what disruption should I expect?
Why it matters: if scaffolding, roof access, or a consumer-unit upgrade are not mentioned in the quote, they may not be included - and they can change the real total significantly.
About paperwork and certification
This is where many homeowners feel lost, and where clarity protects you most.
- Will the installation be MCS-certified, and what MCS paperwork will I receive after completion?
- Who handles the DNO notification or application, and which route applies to my system size?
- What documents will I receive for applying to a Smart Export Guarantee tariff?
- What handover paperwork will I get - warranty certificates, system spec, and a point of contact?
Why it matters: Energy Saving Trust recommends using MCS-certified installers, and an MCS-certified installation is often relevant to export-payment eligibility. A solar PV system also has to be registered or notified to your local Distribution Network Operator - for smaller systems this is usually a G98 notification after commissioning, while larger systems may need a G99 application before connection. The installer will usually handle this, but you should ask who is responsible and get it confirmed in writing. For export income, the Smart Export Guarantee tariff itself is applied for through an energy supplier, not the installer - and Ofgem explains that SEG licensees set their own rate and terms, so this should be treated as tariff-dependent, not a fixed figure every supplier pays.
About the battery, if one is included
A battery can be a good addition or an expensive default. These questions tell you which.
- What is the battery's usable capacity, and what evening demand is it designed to cover?
- Can you show me the battery as a separate line item, with its own payback calculation?
- What is the battery warranty, and who stands behind it?
- Can this battery work with a time-of-use tariff?
Why it matters: a battery should be justified by your actual usage pattern, not added because "everyone gets one now". If it cannot be assessed as a separate purchase on its own merits, you do not yet have enough information to agree to it.
About aftercare
The sales conversation is rehearsed. The aftercare answer rarely is - which is why it tells you so much.
- If I have a performance problem two years after installation, what exactly is the process?
- Who is the specific contact for aftercare queries?
- What does the workmanship warranty cover, and is it backed by insurance?
- Why is this system better suited to my home than a simpler or cheaper option?
Why it matters: a long warranty number from a company with unclear aftercare is worth less than a clear, specific aftercare process from a company with a track record. You want a named contact, a process, and a timeframe - not reassurance.
Before you pay a deposit
Once you have asked these questions of each installer, you are in a position to compare answers rather than impressions. Before committing, make sure you understand the final price, the full specification, what happens if a survey changes the quote, the cancellation terms, and who is responsible for both the paperwork and the aftercare.
If an installer is genuinely good, clear questions will not be a problem. The reaction to being asked is part of the answer.
Related guides
If you already have a quote, start with what to check on a solar quote. If something about a proposal feels off, compare it with the guide to common solar quote red flags.
FAQ
What questions should I ask before signing a solar contract?
Cover six areas: system size and panel wattage; inverter model and warranty; what is and isn't included in the price; who handles MCS, DNO and SEG paperwork; battery capacity and separate cost if included; and the workmanship warranty and aftercare process. Ask each installer the same questions so you can compare answers directly.
How do I know if a solar installer is trustworthy?
Look at how specifically they answer detailed questions, not how confident they are while selling. A stronger installer gives clear answers about scope, warranties and aftercare. If something stays vague after two direct questions on the same topic, treat it as a warning sign and ask for the answer in writing.
Should I ask every installer the same questions?
Yes. Asking each installer an identical set of questions turns a sales pitch into a structured comparison and makes real differences between quotes visible.
Who handles DNO notification for solar panels?
A solar PV system must be registered or notified to your local Distribution Network Operator. For smaller systems this is usually a G98 notification after commissioning; larger systems may need a G99 application before connection. In many domestic installations the installer handles this, but confirm who is responsible in writing.
Do I need to understand the technical details myself?
No. The goal is not to become a solar expert. It is to ask clear questions and notice whether the answers are specific and consistent - which is what tells you how the installer will behave once the sale is done.
Sources
- Energy Saving Trust: Solar panels
- Ofgem: Smart Export Guarantee
- National Grid: G98 microgeneration
- National Grid: G99 generation
Disclaimer
This article is general information only. It is not financial, legal, tax, technical, engineering or regulated professional advice. Always verify quote details, warranty terms, certification status, tariff terms and installer responsibilities directly before signing or paying a deposit.