Use the good roof first
Maximise sensible, productive roof space before paying for panels on a weak roof face simply to increase the panel count.
One homeowner. Five very different answers.
Buying solar in the UK shouldn't feel this complicated.
I started with a simple question: what solar and battery system makes sense for our house? The quotes that came back varied hugely in panel count, roof faces, battery size, inverter power, backup capability and claimed payback.
This is a personal project diary, not financial or electrical advice. Prices and tariffs are a September 2026 snapshot and every property is different.
Why I made this
The quote price was only part of the decision.
I quickly learned that two systems at a similar price can be completely different products. A smaller array with a bigger battery is not the same as a larger array with a smaller battery. A 5 kW inverter is not the same thing as a 10 kW inverter. “Backup” might mean a single emergency socket, selected house circuits, or a much more comprehensive setup.
Most importantly, the software assumptions matter. The same roof can be modelled with different slopes, shading factors, consumption figures, tariffs and future energy inflation. Those assumptions can move the advertised payback by years.
Our priorities
What we were actually trying to achieve
The “best” system is the one that fits the household. These were the things that shaped our choice.
Size for the future
We already have a PHEV and expect a heat pump later, so inverter headroom and expandable storage mattered more than optimising only for today's loads.
Make backup meaningful
Keeping Wi‑Fi, smart-home control, lighting, refrigeration and selected sockets alive in a power cut was a real requirement, not a brochure extra.
Model the tariff we use
We can buy very cheap overnight electricity, so the battery can earn its keep in winter by shifting cheap grid energy as well as storing solar.
The comparison
Five proposals, five different designs
These are snapshots from quotes/configurators I received for the same property. They are not perfectly like-for-like, which is exactly the point.
Swipe sideways on mobile.
| Installer / stage | Solar | Inverter | Battery | Backup / EV | Price snapshot | What stood out to me |
|---|---|---|---|---|---|---|
| EcoGlow Chosen |
24 × 465W DMEGC 11.16 kWp Modelled 10,097 kWh/yr |
Fox KH10 10 kW |
Fox EP12 Plus 11.52 kWh nominal ~10.36 kWh usable in proposal |
Zappi included Selected-circuit automatic backup added |
£14,520 base £15,720 incl. £1,200 backup upgrade |
Largest sensible array, 10 kW inverter, expandable heated battery, EV charger included, physical site survey and practical cable/making-good discussion. |
| Professional Energy Solutions Detailed proposal |
18 × 470W DMEGC 8.46 kWp Modelled 7,639 kWh/yr |
Fox H1 G2 6 kW |
Fox EP12 Plus 11.52 kWh nominal |
Backup +£1,100 EV charger +£1,150 |
£12,750 base £13,850 incl. backup |
A strong, sensible design that deliberately avoided the north-facing roof. The main trade-off for me was the 6 kW inverter versus the larger future-facing option. |
| Glow Green Tesla proposal |
16 × 475W DMEGC 7.60 kWp Modelled 6,107 kWh/yr |
Tesla Powerwall 3 configured to 5.0 kW |
Tesla Powerwall 3 13.5 kWh |
Tesla Gateway included | £13,740.33 | The design used three roof faces, including a very northerly one. It also assumed a shading factor of 1.00. That prompted me to challenge whether every proposed panel was really earning its place. |
| Heatable 20-panel comparison option |
20 × 485W LONGi 9.70 kWp |
Sigenergy SigenStor EC 8.0 kW |
SigenStor BAT 10.0 9.04 kWh 8.76 kWh usable shown |
Integrated system proposition | £15,605 | High-quality-looking package and a large array, but at a materially higher price than some alternatives. It reinforced how much the roof-layout assumptions drive the result. |
| Octopus Energy Early online estimate |
10 panels Online layout stage |
Fox EVO 5 package shown | Configurable portal recommended smaller storage initially |
Online package estimate | £10,149 shown for 10 panels + Fox EVO 5 package | Useful as a national benchmark, but the early automated design was much smaller than later site-specific proposals. I treated it as a starting point rather than a final engineered answer. |
Quote snapshot dates: September 2026. Prices may have changed, and optional extras differ between suppliers. This table describes what was proposed to one house; it is not a ranking of installers.
Installer due diligence
The star rating is not the review.
This became one of the most important parts of my search. A great score on one website can be reassuring, but I would never choose a solar installer from one review platform alone.
Check more than one platform
I would look at Google, Trustpilot and, where relevant, a trade or local-review platform. Each has a different mix of customers and review collection methods, so the pattern across them matters more than one headline number.
Review the service you are actually buying
A company may sell boilers, heat pumps, EV chargers and solar. Thousands of excellent reviews for another part of the business do not automatically tell you how good its solar design, installation and aftercare are. Search within reviews for words such as solar, battery, inverter and aftercare.
Read the newest and the worst
The average score hides the useful detail. Sort by recent reviews, then deliberately read the lower-rated ones. I was looking for repeated themes: missed appointments, subcontractor problems, poor communication, installation quality, commissioning delays and how warranty issues were handled.
How a firm responds matters
Problems happen. A calm, specific response that explains how an issue was fixed can be more reassuring than a page of perfect reviews. Repeated complaints with defensive or generic replies were much more concerning to me.
Look for local evidence
Recent installations near you are useful because they tell you the company is actively working with similar roofs, local grid conditions and access constraints. If I were unsure, I would ask for one or two recent local customers who are happy to be contacted.
Reviews are only one layer
I also checked whether the installer could support the technical promises in the quote: MCS/NICEIC credentials where applicable, warranties, DNO process, written scope, payment protection and who would actually attend site. Reviews should reinforce that evidence, not replace it.
My rule of thumb
Three sources beat one score.Google for local/current experience, Trustpilot for scale and trend, plus a trade/local source or direct recent references. Then search specifically for the product you are buying and read the low-scoring reviews as carefully as the five-star ones.
A lesson from my own shortlist: one national installer looked very reassuring from its overall Trustpilot presence, but the picture was less clear when I checked Google and focused specifically on solar rather than the company's other services. That did not automatically make it a bad installer; it simply showed why a single headline score can be misleading.
What changed my thinking
The useful questions were not “which panel is best?”
Most mainstream panels are good enough that the design, electrical architecture and assumptions can matter more than obsessing over a tiny difference in module efficiency.
kW and kWh are different
kW is power — how fast the system can supply or absorb energy. kWh is capacity — how much energy is stored or consumed over time. A big battery behind a small inverter and a smaller battery behind a large inverter behave very differently.
Export limit ≠ house-use limit
A DNO may approve a system with an export limit. That does not automatically mean the house can only use that same amount internally. Ask the installer to explain the approved export limit, inverter capability, battery output and backup/EPS output separately.
“Backup” needs defining
Ask exactly what stays on during an outage. One emergency socket is not the same as an automatically backed-up consumer unit feeding lighting, network equipment, refrigeration and selected sockets.
North-facing is not automatically wrong
It can still generate electricity, particularly on shallow roofs, but the marginal generation must justify the panel, labour, inverter input and roof space. Ask for the predicted annual output of each roof face separately.
Shading assumptions can swamp small spec differences
If one proposal assumes zero shading and another applies a large shading penalty to the same roof, do not just average the two numbers. Ask how each figure was derived and whether anyone has physically inspected the property.
Tariffs change the battery maths
A home with very cheap overnight power has another use for a battery: charge cheaply and discharge through expensive daytime periods. A payback model that ignores your actual tariff can be misleading.
Future loads can justify inverter headroom
A heat pump, full EV, induction cooking or more electrification can increase instantaneous demand. Bigger is not always better, but future loads should be discussed before locking in an inverter architecture.
Panel count is not a quality metric
“We can fit 24” and “we recommend 24” are different statements. I wanted each roof face to have a reason for being used, not simply the largest headline number.
Where we landed
Our chosen system
We chose EcoGlow's larger Fox-based design, then added the more comprehensive selected-circuit backup option. The final roof count is still subject to precise scaffold-level measurement; if a panel does not physically fit, it should come off rather than be forced into the design.
Solar24 × DMEGC 465W / 11.16 kWp
InverterFox KH10 / 10 kW single phase
BatteryFox EP12 Plus / 11.52 kWh nominal
EV chargingZappi tethered charger
BackupAutomatic selected circuits
Price£15,720 including backup upgrade
Simple sense-check
Rough payback calculator
This deliberately simple model makes the assumptions visible. It is useful for challenging a sales forecast, not replacing a full design model.
Illustrative result
7.2years simple payback
Solar self-use value£1,137
Export income£600
Cheap-rate battery shifting£458
Total annual benefit£2,195
Defaults mirror my conservative planning case, not the installer's advertised 5-year payback.
Avoid double-counting: the “cheap-grid energy shifted” box is intended for grid energy bought cheaply and used later. If you are modelling solar that charges the battery, do not count the same solar kWh again as both self-use and battery arbitrage.
Before signing
The questions I would now ask every installer
- What annual electricity usage have you modelled? Is it my real usage or a default?
- Show me each roof face separately. Orientation, pitch, panel count and predicted annual generation.
- How did you calculate shading? Desktop estimate, horizon survey, physical site survey or optimiser/microinverter assumption?
- Why this many panels? Is the layout physically measured, and what happens if the scaffold survey finds less space?
- What limits the power? Inverter AC output, battery charge/discharge output and EPS/backup output are separate numbers.
- What exactly is the DNO application for? What has been submitted, what export limit is requested/approved, and is export limitation part of the design?
- What does “backup” actually power? Get the exact sockets/circuits/consumer-unit arrangement in writing.
- How much battery is usable? Ask about depth of discharge, cold-weather behaviour, warranty, cycles and expansion options.
- What is included in the price? Scaffolding, bird protection, DNO work, MCS/NICEIC certification, EV charger, backup hardware, cable routes and making good.
- Which tariff assumptions produce the payback? Import rate, cheap window, export rate, energy-price inflation and annual degradation.
- What changes if I add a heat pump or EV? Ask before choosing the inverter and battery architecture.
- Who supports it after installation? App setup, commissioning, fault diagnosis and warranty handling matter for a system expected to last decades.
- What do the reviews look like away from the headline score? Check at least two or three sources, search for solar-specific feedback, read recent low-rated reviews and look at how the installer responds when something goes wrong.
Plain English
Solar jargon in 60 seconds
kWpPeak rated size of the solar array under test conditions.
kWInstantaneous power — how fast energy is flowing.
kWhEnergy over time — battery capacity and electricity usage.
DNOYour local electricity distribution network operator.
G99 / export approvalThe connection process relevant to larger generation/storage systems. Exact requirements depend on the design and network.
EPS / backupEmergency power supply when the grid is unavailable, subject to the system and circuits configured.
DoDDepth of discharge — how much of a battery's nominal capacity is intended to be usable.
Round-trip efficiencyHow much energy comes back out compared with what went into the battery.
Project status
September 2026
The EcoGlow proposal has been accepted. The DNO application has been submitted, scaffolding is being arranged, and the roof will be measured precisely before the final panel layout is locked down. I will update this page with actual generation, battery behaviour and bills once the system has real-world data behind it.