What to Check Before Buying a Plug-in Solar Kit

You've decided you want plug-in solar. Now you need to choose a kit. There are dozens available, and the differences between a good one and a mediocre one aren't always obvious until you've installed it and lived with it for a few months.

This checklist will help you spot the good ones and avoid the pitfalls.

1. Is It UKCA or CE Marked?

Your panel and inverter must have either UKCA (UK Conformity Assessed) or CE marking. Look for these marks on the product itself or in the documentation.

What this means: the product has been tested and meets UK safety and performance standards.

Why it matters: Unmarked or non-compliant products could be unsafe or might not work properly. You're bringing electrical equipment into your home—it needs to be safe.

What to do: Check the product page before you buy. If there's no mention of UKCA or CE, ask the seller. Any legitimate solar retailer will have this information readily available.

2. Does It Have a Recognised Micro-Inverter Brand?

The micro-inverter is the electrical brain of the system. Common brands include Enphase, Hoymiles, Deye, Solis, and a few others. These are well-established, reliable companies with customer support and replacement parts availability.

Budget or unknown-brand inverters might be cheaper, but if something goes wrong in year five, you might struggle to find support or replacement parts.

What to do: Check the inverter brand before you buy. If it's an unfamiliar brand, research it. Does it have a UK presence? Are there reviews mentioning reliability? If you can't find any information, it might be a knock-off or a product with poor support.

3. What's the Warranty?

A good kit includes warranties for:

• Panels (performance warranty): Should be at least 10–25 years, often more. This guarantees the panel will retain 80%+ of its rated output for the period.

• Micro-inverter: 5–10 years is normal. Some premium brands offer longer.

• Mounting hardware: Usually covered under a general product/materials warranty, 2–5 years.

The fine print: Read what's actually covered. Some warranties cover manufacturing defects but not damage from improper installation or acts of weather. Is it a "replacement" warranty (they send you a new unit) or "repair only" (they fix the broken one)? Replacement is better.

Baseline: If a kit has less than 5 years on the inverter or less than 10 years on the panels, it's not offering you good protection. Walk away.

4. Is the App Good?

You're going to check your generation data on the app regularly. A good app is intuitive, shows real-time generation, historical data, and doesn't crash or lose connection.

What to do: Download the app before you buy (it's free). Create a demo account if possible, or read the reviews. Look for reviews mentioning app crashes, poor UI, or loss of connectivity. If the reviews are consistently poor ("terrible app," "crashes constantly," "useless"), that's a red flag.

A good app should show you: current watts, today's kWh, weekly and monthly generation, any error messages, and ideally a simple interface with good graphs.

5. What's the Cable Length?

Standard kits come with 5–10 metres of pre-terminated cable. Check how long yours is.

Most homes have an outdoor socket within 5–10 metres of where you're planning to mount the panel. If your socket is further away (or you're planning an indoor install via a window), you'll need to extend the cable or be creative with routing.

What to do: Measure from your intended panel location to your nearest socket. If the cable length is shorter than that distance, you'll need to buy an extension cable (costs £20–50). Plan ahead.

6. Are the Mounting Options Suitable for Your Surface?

A kit will come with mounting hardware suited to one or two specific surfaces (usually balcony rail, ground stakes, or A-frame). If your installation type isn't covered, you'll need to buy additional hardware.

What to do: Check the spec sheet. It usually says "suitable for balcony rail mounting" or "ground stake included" or "compatible with weighted A-frames." If you're planning a specific install type (say, flat roof ballast mounting) and the kit doesn't mention compatibility, ask the seller whether you can use their panel with a third-party ballast frame.

Most panels work with any standard ballast frame, but there can be edge cases with unusual connector types or cable lengths.

7. What's the Post-Purchase Support Like?

If something goes wrong after you've installed it, can you reach a human and get help?

What to do: Before you buy, try contacting the company's support. Send an email and see how long it takes to get a reply. Call their phone line (if they have one) and see if you can reach someone. If you get a reply within a business day and they actually answer your question, that's a good sign. If the contact form goes unanswered for a week, that's a bad sign.

Check reviews mentioning customer service. Look for patterns. Is support generally helpful or do people complain they can't reach anyone?

8. Is It BSI Standard Compliant? (From July 2026)

From 15 July 2026, compliant kits must meet the new BSI product standard for plug-in solar systems (BS 8990). This is a UK-specific standard that ensures products are safe and compatible.

What this means: Until July 2026, there's no formal BSI product standard, so non-compliant kits are being sold. From July onwards, you shouldn't buy kits that don't meet BS 8990.

What to do: If you're buying before July 2026, acknowledge that you're buying a kit that doesn't yet have BSI compliance. It's not a major problem (these systems are generally safe), but it's worth understanding.

If you're buying after July 2026, ask the seller: "Does this kit meet BS 8990?" If they say no, don't buy it.

9. What's the Returns Policy?

If you buy a kit online and it arrives damaged, or you open it and realise you made a mistake, can you return it?

What to do: Check the seller's returns policy before you buy. Most reputable retailers offer 14–30 days to return unopened items, and some offer returns even after opening as long as it's within a certain window. If there's no mention of a returns policy, that's a red flag.

10. Have You Read Our Installation Articles?

Before you commit to a kit, confirm that you have a suitable location for it and that you understand the installation process.

What to do: Spend 20 minutes reading our guides on choosing a location, mounting options, and installation. Make sure you're confident about where you'll put the panel and how you'll run the cable to your socket.

If you're uncertain about any aspect of the install, ask for help (a local tradesperson can do it for £100–200) or choose a different mounting surface.

The Checklist

Before you buy, verify:

• UKCA or CE marking ✓
• Recognised inverter brand ✓
• Panel warranty at least 10 years ✓
• Inverter warranty at least 5 years ✓
• App is reviewed well ✓
• Cable length is suitable for your layout ✓
• Mounting hardware suits your surface (or third-party compatibility confirmed) ✓
• Support is reachable and responsive ✓
• BSI compliance (if buying from July 2026) ✓
• Returns policy is clear ✓
• You've confirmed your installation location is viable ✓

If a kit ticks at least 8 of these 10 boxes, it's probably a good choice. If it ticks fewer than 6, keep looking.

Price

Notably absent from this checklist: price. That's intentional. A cheap kit that fails in year two, or that has terrible support, is more expensive than a mid-range kit that works reliably for 25 years. Budget kits can be decent, but don't let price be the deciding factor. Prioritise quality and support.

A sensible budget for a single 400W panel kit is £500–1000 depending on mounting hardware and brand. If something costs significantly less, ask why. If it costs significantly more, make sure you're getting genuine added value.

Making the Decision

You're ready to buy when:

• You've identified your installation location (and confirmed it has good sun and a workable cable route).
• You've chosen a kit that ticks most of the checklist boxes.
• You're confident in the support and warranty.
• You've either confirmed you can install it yourself or you've budgeted for a tradesperson to help.

From that point, it's just execution. Unbox, mount, connect, generate. The hard thinking is done.

For a step-by-step walkthrough of installation, see our full installation guide.