How to Avoid Solar Sales Traps in the UK

Solar can be a genuinely good investment for the right home. It can also be oversized, oversold and underwhelming — and the difference often comes down to who gave you the advice. Almost everyone in the quoting chain earns more when you buy a bigger system, so the honest question — does this pay for you, or not? — rarely gets asked. This guide walks through the four traps we see most, and how to protect yourself.

Trap 1: Pressure selling and the 'today only' discount

The oldest trick in the book. A salesperson sits at your kitchen table for two hours, quotes a scary number, then produces a 'director's discount' that vanishes if you don't sign tonight. Legitimate engineering doesn't expire at midnight.

• No reputable installer needs a same-day signature. A real quote is still valid next week.
• Get at least three written quotes. Compare the kWp size, the panel and inverter models, and the total installed price — not the monthly finance figure.
• Check the firm is MCS-certified. Without MCS you cannot claim SEG export payments, and you lose a key quality safeguard.

Trap 2: Inflated SEG export promises

The Smart Export Guarantee (SEG) pays you for electricity you send back to the grid. Salespeople love to model a big system on the assumption you'll export loads at a generous rate — but SEG rates are set by retailers and are volatile.

As at the last_verified date of this pack (October 2026), SEG offers across the market span roughly 4 to 16.5 p/kWh. For context, Octopus Outgoing has sat around 12p flat and standalone SEG around 4.1p — but these can change with just 30 days' notice, so treat any figure in a sales deck with suspicion and confirm the current rate before you buy.

Here's the catch almost no salesperson mentions: exported electricity is worth far less than electricity you use yourself. You buy grid power at roughly 24.67 p/kWh (the Ofgem cap resets quarterly, so check your own bill), but you might only be paid single-digit pence to export. Every unit you self-consume is worth two to six times more than one you sell. A model that leans heavily on export income is usually flattering the numbers.

• A premium time-of-use export tariff (such as Intelligent Octopus Flux) can genuinely improve the case — but it typically requires a battery, which is a separate cost.
• Your export tariff can come from a different supplier than your import tariff. You're not locked in.

Trap 3: Oversized systems you'll never use

Bigger systems mean bigger invoices, so there's a constant nudge towards more panels than your roof and your usage justify. In the UK a panel array yields roughly 850 kWh per kWp per year on average — nearer 900–1,000 in South England, around 800 in the North, and 750–800 in Scotland. That's the realistic ceiling, not the optimistic one.

The saving that actually lands in your pocket comes from self-consumption, typically worth around £400–£700 a year for a well-matched household. Panels generating power you can't use and can only export cheaply add cost without adding much value.

There's also a technical ceiling. Systems above 3.68 kW per phase need a G99 application to your DNO, and the DNO may impose an export limit — larger single-phase systems are often capped at 3.68 kW of export anyway. Below that threshold you're on simple G98 notify-within-28-days. An oversized array can therefore hit a wall the salesperson never warned you about.

Size the system to your actual daytime consumption and roof, not to the salesperson's commission.

Trap 4: Finance framing and the battery upsell

A system quoted as '£X a month' hides the real price, the interest and the true payback. Always ask for the cash price and the total you'll repay over the term. Note that there is currently 0% VAT on residential solar PV and batteries (including standalone retrofit batteries) until 31 March 2027 — a genuine saving, so make sure it's reflected in your quote.

Batteries get bundled in aggressively. There is no general household grant for a battery — the case rests entirely on self-consuming more of your solar, charging cheaply overnight on a smart tariff, and accessing a premium export tariff. Indicative installed costs run around £3,500–£5,000 for 5 kWh and £6,500–£9,000 for 10 kWh, with typical payback of 7–12 years. For some households that stacks up; for others it simply doesn't, and no amount of bundling changes that.

Why independent advice pays

Even the 'free' comparison sites get paid by the installer they refer you to. We take nothing from any installer — we sell and install nothing, and charge a small fixed fee (£150 residential, £700 commercial) for engineered advice. That means the honest answer is on the table: sometimes solar, a battery, or a particular system size simply won't pay for you, and we'll tell you so. On a five-figure decision, a modest fee that might save you from an oversized system or steer you to the right tariff is cheap insurance.

Everyone else in the solar chain earns more when you spend more. We don't. Our only job is to tell you whether it pays — and if it doesn't, that's the most valuable thing we can say.

Figures in this guide are current at the date of publication and indicative only — SEG/export rates change with 30 days' notice, the Ofgem price cap resets quarterly, and grant terms change. Confirm the current numbers for your situation before you commit. This is general information, not personal financial advice.