Choosing a solar panel installer is one of the most important decisions you will make for your home. The right installer ensures your system performs efficiently, qualifies for government payments, and comes with reliable warranties. Asking the right questions before you sign a contract can save you thousands of pounds and years of frustration.
The most important question to ask a solar panel installer is whether they are MCS-certified and registered with TrustMark, as this ensures the installation meets industry standards and qualifies you for the Smart Export Guarantee payments. Without MCS certification, you cannot receive SEG payments from your energy supplier, making your investment significantly less valuable.
What matters when you choose a solar installer is their accreditation, warranty terms, and how they handle site-specific factors like your roof condition and shading. The following ten questions cover everything you need to know before committing to a quote.
| Question | Why It Matters | What to Look For |
|---|---|---|
| Are you MCS-certified and TrustMark-registered? | Required for SEG payments and consumer protection | MCS certificate number and TrustMark logo on quote |
| What panel and inverter warranties do you offer? | Long-term protection against product failure | 25-year panel performance warranty; 10-year inverter warranty |
| Will the system qualify for the Smart Export Guarantee? | Earns money for excess electricity exported to grid | MCS certification and approved export meter |
| How will you assess my roof’s suitability? | Ensures roof can support panels and generate efficiently | Structural survey and pitch/orientation analysis |
| Can you integrate battery storage now or later? | Boosts self-consumption and reduces bills | AC-coupled system for future retrofitting |
| How will you handle shading on my roof? | Shading can cut output by 10-20% | Microinverters or power optimisers in quote |
| What is total installed cost including scaffolding and VAT? | Scaffolding can add £500-£1,000 | Fixed-price quote with no hidden fees |
| How long will installation take and what access is needed? | Affects disruption to your home and neighbours | 1-3 day installation with full scaffolding and waste removal |
| What monitoring system do you provide? | Lets you track generation and spot faults early | App or web portal with real-time data |
| What aftercare and support do you offer? | Peace of mind if something goes wrong | Handover pack, emergency call-out, remote diagnostics |
1. Are you MCS-certified and TrustMark-registered?
This is the single most important question. MCS certification is mandatory for any solar installation to qualify for the Smart Export Guarantee, which pays you for electricity you export to the grid (MCS, 2026). TrustMark registration provides government-backed consumer protection, meaning you have recourse if the work is substandard (TrustMark, 2026). Without both, you cannot receive SEG payments from your energy supplier (Ofgem, 2026).
- Ask for the installer’s MCS certificate number and verify it on the MCS website
- Check they are listed on the TrustMark website for consumer protection
- Confirm they will register your system for SEG after installation
2. What panel and inverter warranties do you offer?
Solar panels typically come with a 25-year performance warranty, but inverters usually last 10-15 years and may need replacing sooner (Energy Saving Trust, 2026). Warranty terms vary significantly between installers, especially for labour. A longer warranty suggests the installer has confidence in the products they use.
- Get the specific warranty period for both parts and labour in writing
- Ask what happens if the manufacturer goes out of business during the warranty period
- Check whether the warranty covers removal and refitting costs if a panel needs replacing
3. Will the system qualify for the Smart Export Guarantee?
The Smart Export Guarantee requires MCS-certified installers and approved metering equipment (Ofgem, 2026). Even with MCS certification, not all energy suppliers offer SEG tariffs, so you need to know your installer can help you register. SEG payments range from 3-15p per kWh exported depending on your supplier.
- Ask which SEG suppliers your installer has worked with before
- Confirm the quote includes the cost of an export meter if required
- Request a written commitment that the installer will handle SEG registration
4. How will you assess my roof’s suitability?
Your roof needs to support the weight of solar panels, and its orientation affects how much electricity you generate. A professional installer should carry out a structural survey, not just a visual check (Energy Saving Trust, 2026). South-facing roofs with a 30-40 degree pitch produce the most energy, but east and west orientations can still be viable.
- Ask if the quote includes a structural survey report
- Request a breakdown of expected annual generation based on your roof’s orientation
- Check if they use solar pathfinder tools or similar shading analysis equipment
5. Can you integrate battery storage now or later?
Battery storage typically adds £2,000-£5,000 to the system cost but can increase your self-consumption from around 30% to 70-80% (Energy Saving Trust, 2026). If you cannot afford a battery now, ask whether the system is designed for easy retrofitting later. AC-coupled systems allow you to add a battery without replacing the inverter.
- Ask whether the inverter is compatible with future battery storage
- Request a quote for adding battery storage at the same time as the panels
- Check if the installer offers a single warranty for combined solar and battery systems
6. How will you handle shading on my roof?
Partial shading can reduce your system’s output by 10-20% (Energy Saving Trust, 2026). A good installer will identify shading from chimneys, trees, or neighbouring buildings and propose solutions. Microinverters or power optimisers can mitigate shading but add cost to the installation.
- Ask for a shading analysis report as part of the quote
- Request a comparison of output with and without microinverters or optimisers
- Check if the installer offers a performance guarantee that accounts for shading
7. What is the total installed cost including scaffolding and VAT?
A typical 4kW solar system costs £5,000-£8,000 including installation, but scaffolding can add £500-£1,000 to the total (Energy Saving Trust, 2026). VAT on solar installations is currently 0% for residential properties (GOV.UK, 2026). Always get a fixed-price quote that itemises every cost.
- Ask for scaffolding costs to be included in the fixed price
- Confirm the 0% VAT is applied correctly on the invoice
- Request a written breakdown of all costs including any disposal fees for old panels
8. How long will installation take and what access is needed?
A standard installation takes 1-3 days depending on system size and roof complexity (MCS, 2026). Scaffolding may be required for roof access, which affects neighbours and parking. Ask whether the installer handles all scaffolding and waste removal themselves.
- Get a confirmed installation timeline in the contract
- Ask if scaffolding will block your driveway or affect neighbours
- Check whether the installer removes and recycles old equipment
9. What monitoring system do you provide?
Most inverters include basic monitoring via an app or web portal showing real-time generation (Energy Saving Trust, 2026). Some installers offer premium monitoring that tracks both export and import, helping you optimise your energy use. Confirm the monitoring system works with your smartphone.
- Ask whether the monitoring app is free or requires a subscription
- Request a demonstration of the monitoring interface before installation
- Check if the system sends alerts for faults or reduced performance
10. What aftercare and support do you offer after installation?
A reliable installer should provide a handover pack with the system manual, warranty documents, and SEG registration details (TrustMark, 2026). Ask about emergency call-out response times and whether they offer annual maintenance checks. Some installers provide remote troubleshooting via app for inverter faults.
- Ask for the installer’s emergency contact number and typical response time
- Request a written aftercare schedule including any annual checks
- Check if remote diagnostics are included in the installation price
Asking these ten questions will help you compare installers on a like-for-like basis and avoid costly surprises. Guide to comparing solar panel quotes Understanding solar panel warranties in the UK Take your time reviewing the answers and always get at least three quotes before making a decision.
Frequently Asked Questions
The most important question is whether they are MCS-certified and TrustMark-registered. According to MCS, this certification is required to qualify for Smart Export Guarantee payments.
Most reputable manufacturers offer a 25-year performance warranty on panels and a 10-year warranty on inverters. The Energy Saving Trust recommends checking these terms before installation.
In most cases, solar panels are permitted development and do not require planning permission. However, GOV.UK advises checking with your local council if your home is in a conservation area or a listed building.
Yes, most modern systems can be retrofitted with AC-coupled battery storage. Ofgem notes that this can increase self-consumption and reduce your electricity bills.
The average cost for a 4kW system on a 3-bed semi is between £5,000 and £8,000 including scaffolding and VAT. The Energy Saving Trust provides a cost calculator on their website.
