Before getting a solar quote, stop. In the UK, solar panel quotes can vary massively — and not always for the right reasons. This guide covers 7 things to know before getting a solar quote.
The UK solar market is busy, and that means a mix of excellent installers… and a fair few cowboys. We regularly see quotes that are under-specced, over-specced, or simply not designed around the way a home actually uses energy.
At Apex Doma, we’ve spent years fixing other people’s mistakes. So we’ve put together seven things you should know before you even ask for a solar quote. Get these right, and you’ll save time, money and a lot of hassle.
Prefer to watch? You can see Ian walk through all 7 points in this video.
1. Know Your Annual Energy Consumption
The very first step before getting a solar quote is understanding how much electricity you use in a year. Without this, any design is guesswork.
Your annual usage in kWh tells an engineer:
- How many solar panels you’re likely to need
- Whether a battery makes sense (and what size)
- What kind of savings you can realistically expect
You’ll usually find this figure on your annual energy statement. If you’re with a supplier like Octopus, it’s often on the front page. If you’ve recently moved, share as much information as you can: past usage, number of occupants, heating type, and so on.
Separate your EV charging
If you have an electric vehicle, try to separate home usage from EV charging in kWh. Most people charge at night on cheap off-peak tariffs, so we often won’t size the solar and battery system around EV consumption. Doing so can add thousands to the quote for very little benefit.
Why this matters
Some installers don’t ask for your usage at all. Under the MCS (Microgeneration Certification Scheme), many default quotes are based around 3,500 kWh per year. That might be wildly wrong for your home.
If nobody asks for your annual kWh, that’s a red flag. A properly designed system starts with your numbers, not theirs.
You can learn more about how solar and batteries affect your bills here.
2. Think Ahead About Future Loads
The second thing to know before getting quotes is what your future energy use might look like.
Are you planning to add:
- A heat pump
- A hot tub
- An EV you’ll charge at home
- Underfloor heating
- An extension or garden room
These can all drastically change how much energy you use.
A good engineer will look at your current usage plus an estimate of future loads. They might:
- Recommend a slightly larger inverter
- Suggest a modular battery system like SigenStor that you can add to later
- Leave space on the roof or in the electrics for a future upgrade
Sometimes the jump from a medium inverter to a larger one is only a couple of hundred pounds. If you only think about today, you might pay far more later to swap everything out.
3. Be Clear On Where You Are In Your Building Journey
Before you get a solar quote, think about what stage your property is at:
- Are you just exploring solar on an existing roof?
- Are you re-roofing?
- Are you building an extension or a new build?
This has a huge impact on the best approach.
In-roof vs on-roof
If you’re doing a new roof or extension, in-roof solar panels can make financial and aesthetic sense. You’re paying for scaffolding anyway, and you won’t need tiles under the panels. On existing roofs where nothing else is changing, on-roofis usually the better option.
Some larger national firms will tell you in-roof “isn’t possible” simply because they don’t offer it. Often, it is possible — they just don’t want the extra work.
We break the differences down in more detail here.
When to involve your installer
For extensions and major works, a good rule of thumb is to engage with a solar installer:
- Around slab stage for an extension
- Or roughly three months before you expect to reach roof height
Most quality installers have a 6–8 week lead time and also need to submit applications to the Distribution Network Operator (DNO) for grid connection approval. Leaving it until the roof is felt and battened and saying “can you come next week?” is asking for stress.
At Apex Doma, we regularly design systems from architect drawings, then come back to measure and mark out once the roof is ready.
4. Research The Products You’re Being Quoted
Before you get too deep into quotes, it’s worth doing a bit of homework on the products themselves:
- Solar panel brands and wattages
- Inverter types and sizes
- Battery systems and capacities
- Warranties and backup options
Think of it like buying a car: there’s everything from budget models to premium brands like Aiko or JA Solar N-Type. On the battery side, there’s a big difference between a basic unit and a system like Tesla Powerwall 3 or SigenStor.
A cheaper quote doesn’t always mean better value. It might mean:
- Shorter warranties
- Lower efficiency panels
- No option for backup during power cuts
- Less flexible or expandable systems
We’ve written detailed guides that can help:
Spending a couple of hours getting familiar with the brands will also help you test whether an installer truly knows their stuff.
5. Decide If You Need Whole-House Backup
A very common assumption is that if you have a battery, your home will stay on when the power goes out.
Unfortunately, that’s not always true.
Batteries and gateways
Some systems require an additional gateway or backup box for the battery to power your home during an outage. For example:
- Tesla Powerwall 3 → needs a gateway to provide backup
- SigenStor → can provide backup when paired with its gateway
Without this extra hardware, your system will shut down in a power cut like everyone else’s.
Who really needs backup?
Whole-house backup is essential for homeowners who:
- Rely on medical equipment
- Live in areas with frequent outages
- Want CCTV, alarms or gates to stay powered
- Run a home office that can’t go down
Backup hardware can add around £1,000+ for single-phase and more for three-phase systems, and won’t usually “pay back” on a spreadsheet. It’s more like an insurance policy.
Before you get quotes, decide whether this is a “nice to have” or an essential. Then make sure every installer knows your answer.
6. Be Honest About Your Budget And Your “Why”
Two questions to ask yourself before getting a solar quote:
- Why am I doing this?
- What budget am I comfortable with?
Knowing your “why”
Common reasons include:
- Cutting bills and protecting against rising prices
- Reducing your carbon footprint
- Gaining whole-house backup during outages
- Preparing for a future heat pump or EV
- Increasing your home’s appeal and value
Each of these leads to a different design. Someone wanting maximum grid independence will likely need more panels. Someone focused on backup might prioritise batteries over panel count. Someone thinking about resale value might care more about aesthetics and premium hardware.
We talk more about value here.
Being open about budget
A lot of people feel awkward sharing a budget, but it’s actually one of the most helpful things you can do. If we know you’re aiming for, say, £10–12k, we can:
- Show you what’s realistic in that range
- Explain what you’d gain by spending slightly more
- Or what you’d compromise by spending less
If an installer knows your budget and still tries to seriously overcharge, their reputation isn’t going to last long — and it’ll become obvious as you compare quotes.
7. Do Your Due Diligence On The Installer
Finally, before you invite anyone round for a survey or accept a quote, take time to check who you’re dealing with.
Accreditation and protections
Look for:
- MCS certification
- Membership of schemes like HIES or RECC
- Insurance-backed deposit protection
- Insurance-backed workmanship warranties
These safeguards exist to protect you if something goes wrong or a company disappears.
Reputation and approach
Signs of a good installer:
- Plenty of recent, detailed reviews
- Willing to visit your home, not just quote remotely
- Talks about design and usage, not just discounts
- Can clearly explain where the inverter and battery will go
- Has been trading for several years and is profitable
We see too many companies chasing the cheapest possible price and then collapsing because they’re not making enough to support customers long term.
At Apex Doma, for example, we always start with an intro call and a first-pass design, then follow up with a full site visit to measure, photograph and plan cable routes. That way, installation day goes smoothly and you get a system built to last.
You can read more about how we work here.
How Apex Doma Helps You Get The Right Solar Quote
Since 2014, Apex Doma has been a family-led, engineering-driven solar installer. We don’t do generic packages or high-pressure sales.
Instead, we:
- Start with your kWh usage and your goals
- Design systems around your home’s layout, future plans and budget
- Use high-quality panels, inverters and batteries from trusted brands
- Carry out thorough home surveys before finalising any quote
- Support you long after the installation is complete
Our aim is simple: to install systems we’d be proud to have in our own homes, and to build long-term relationships with the people we work with.
7 Things Before A Solar Quote – FAQs
Yes. Your annual kWh is the foundation of a proper design. Without it, an installer is guessing, and you risk an under- or over-specced system.
No. It’s usually best to involve a solar installer a few months before roof height. That way the system can be designed into the project from the start and you can reuse scaffolding and planning already in place.
Not always, but they’re rarely tailored. They usually ignore your actual usage, roof layout and future plans. It’s far better to have a system designed around your home than trying to squeeze your needs into a one-size-fits-all deal.
Most homeowners get two or three. That’s enough to spot any outliers and compare approaches, without turning it into a full-time job. Focus on quality of design and installer reputation, not just the lowest price.
Our Solar Advice section is a great place to start. You’ll find guides on batteries, Powerwall 3, in-roof vs on-roof, and whether solar can increase the value of your home.
