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(UK Sizing Guide)", "description": "The answer isn't the same for every home. It depends on how much electricity you use, when you use it, whether you're adding a battery, and how much roof space you have.", "image": "https://alliantenergy.co.uk/assets/home-solar-D_Eyt8mX.jpg", "author": { "@type": "Person", "name": "Alliant Energy Team", "url": "https://alliantenergy.co.uk/about" }, "reviewedBy": { "@type": "Person", "name": "MCS Registered Engineer", "jobTitle": "MCS Registered Engineer" }, "publisher": { "@type": "Organization", "name": "Alliant Energy", "url": "https://alliantenergy.co.uk", "logo": { "@type": "ImageObject", "url": "https://alliantenergy.co.uk/logo.png" } }, "datePublished": "2026-01-15", "dateModified": "2026-05-19" }, { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "Can I have too many solar panels?", "acceptedAnswer": { "@type": "Answer", "text": "Technically yes — if you generate significantly more than you can use or store, the excess is exported at low SEG rates. Oversizing also means a higher upfront cost without proportionate savings. A properly sized system generates slightly less than annual demand, with a battery covering the gap." } }, { "@type": "Question", "name": "What if I can't fit enough panels for my usage?", "acceptedAnswer": { "@type": "Answer", "text": "Install what fits and accept that solar covers a portion of your demand rather than all of it. Even a partial-coverage system is valuable. Alternatively, higher-wattage panels (500W+) in the same footprint will generate more." } }, { "@type": "Question", "name": "Does it matter which direction my roof faces?", "acceptedAnswer": { "@type": "Answer", "text": "Yes, but east and west-facing roofs are still viable — they generate around 15–20% less than a south-facing equivalent. Many installations use both sides of a pitched roof (east + west), which provides more consistent generation through the day than a single south-facing array." } } ] } ] --- [![Alliant Energy — Renewable Energy Solutions](/__l5e/assets-v1/3bd22195-cc6e-43e6-b5ff-5a808ce292d3/alliantenergyltd-2.svg)](/) [Home](/)[About](/about-us) [Services](/services) [Guides](/guides)[Case Studies](/case-study)[![Levelise](/__l5e/assets-v1/59fd362e-361a-47d7-ad1f-65e9beeb5289/levelise-logo.webp)](/guides/levelise-hub-explained) [01282 501589](tel:01282501589)[Get a Quote →](/quote) Spoke guide · Sizing # How Many Solar Panels Do I Need? (UK Sizing Guide) The answer isn't the same for every home. It depends on how much electricity you use, when you use it, whether you're adding a battery, and how much roof space you have. By **Alliant Energy Team**· reviewed by MCS Registered Engineer Last updated 19 May 2026 [Get a Quote](/quote) [View Packages](/services/solar) On this page - [Start with usage](#usage) - [Panel generation](#generation) - [Self-consumption](#self-consumption) - [Sizing calculation](#sizing) - [Roof space](#roof) - [Our packages](#packages) - [FAQ](#faq) Ready to act? Free quote in one working day. [Get a Quote →](/quote) This guide walks you through the calculation — from your annual kWh usage to the right number of panels and battery size for your home. ## Start with your electricity usage The starting point is your annual electricity consumption in kWh. You'll find this on your electricity bill. The UK average is around 3,500 kWh/year for a typical household — but actual usage varies considerably: Household type Typical annual usage 1–2 bed flat or small home 1,500–2,200 kWh/yr 3-bed semi (2 adults) 2,800–3,800 kWh/yr 4-bed detached (family) 3,500–5,000 kWh/yr Home with EV (charging at home) Add 2,000–4,000 kWh/yr Home with air source heat pump Add 2,500–5,000 kWh/yr If you have an EV or are planning to get a heat pump, your electricity demand is significantly higher — and sizing your solar system to cover that demand makes the economics much stronger. ## How much does a solar panel generate in the UK? A single 465W panel in the UK generates approximately 390–430 kWh per year, depending on roof orientation, pitch and location. Here's a quick reference: Panel count System size (kWp) Est. annual generation (South-facing) 6 panels 2.79 kWp 2,200–2,600 kWh/yr 8 panels 3.72 kWp 2,900–3,500 kWh/yr 10 panels 4.65 kWp 3,600–4,300 kWh/yr 12 panels 5.58 kWp 4,400–5,100 kWh/yr 16 panels 7.44 kWp 5,800–6,800 kWh/yr Note East or west-facing roofs generate around 15–20% less than south-facing. North-facing generates around 30–40% less. We account for this in your site-specific projection. ## The self-consumption question Generating 3,500 kWh per year doesn't mean you use all 3,500 kWh. Without a battery, homes typically self-consume 30–40% of generation. The rest is exported to the grid at SEG rates (4–15p/kWh) while you continue buying from the grid at 24–28p/kWh. A battery changes this. With a 5.76 kWh battery, self-consumption typically rises to 60–75%. With an 11 kWh battery and smart tariff integration, you can exceed 80% in summer. The optimal battery size depends on your daily evening usage — there's no point in a 20 kWh battery if you only use 3 kWh after dark. ## A simple sizing calculation Here's a worked example for a 3-bed semi using 3,500 kWh/year: - Step 1 — Target generation: match your usage. Aim for 3,000–4,000 kWh/yr from the panels. - Step 2 — Panel count: 3,500 kWh ÷ 430 kWh/panel = approximately 8 panels (3.72 kWp). - Step 3 — Battery size: evening demand is typically 1.5–3 kWh. A 5.76 kWh battery covers most households' evening use. - Step 4 — Reality check: do you have 8 panels' worth of useable, non-shaded roof facing south/south-west? A west-facing roof might need 10 panels to achieve equivalent generation. EV owners For EV owners, upsize the system. An EV adds 2,000–4,000 kWh/year of demand. An 8-panel system will struggle to make a meaningful dent in that — 12 panels with an 11 kWh battery is a better starting point. ## Roof space: how much do you need? A standard 465W panel is approximately 1.75m × 1.13m. That's around 2 m² per panel. Eight panels need roughly 16 m² of clear, unobstructed roof space — feasible on most 3-bed semis with a south or south-west facing slope. Roof obstructions (skylights, chimneys, vents) reduce useable space. Our pre-installation survey confirms what's available and designs the array layout accordingly. ### Get a site-specific projection We size on your actual usage — not on maximising hardware sold. [Get a Quote](/quote) [View Packages](/services/solar) ## Our standard packages — and why they're sized the way they are Our three packages reflect the most common domestic requirements: - Package 3 (6 panels, 5.76 kWh battery, £5,999): right for homes using under 3,000 kWh/year or with limited roof space. - Package 2 (8 panels, 5.76 kWh battery, £6,999): best match for a typical 3–4 bed home using 3,000–4,000 kWh/year. Our most popular. - Package 1 (12 panels, 11 kWh battery, £9,000): homes using 4,000+ kWh/year, EV owners, or anyone looking to maximise generation and self-consumption. If your situation doesn't fit neatly into one of these, we'll specify a custom system. ## Frequently asked questions ### Can I have too many solar panels? Technically yes — if you generate significantly more than you can use or store, the excess is exported at low SEG rates. Oversizing also means a higher upfront cost without proportionate savings. A properly sized system generates slightly less than annual demand, with a battery covering the gap. ### What if I can't fit enough panels for my usage? Install what fits and accept that solar covers a portion of your demand rather than all of it. Even a partial-coverage system is valuable. Alternatively, higher-wattage panels (500W+) in the same footprint will generate more. ### Does it matter which direction my roof faces? Yes, but east and west-facing roofs are still viable — they generate around 15–20% less than a south-facing equivalent. Many installations use both sides of a pitched roof (east + west), which provides more consistent generation through the day than a single south-facing array. Three ways to get started ## Ready to find out what solar saves you? Get a tailored quote in one working day. No obligation. No hard sell. Speak to a renewable energy engineer — not a salesperson — at a time that suits you. [Get a Quote → ](/quote) [Request a Callback →](/request-callback) [Download Brochure →](/brochure) Accreditations ## Certified, registered, and insured. Every time. MCS certification isn't a box-ticking exercise — it qualifies your system for Smart Export Guarantee payments and government grants. Our installers are also NICEIC-approved and TrustMark-registered, and every install is fully insured. ![Citation ISO Certification: ISO 9001 quality management, ISO 14001 environmental management and ISO 45001 occupational health and safety](/__l5e/assets-v1/180183cd-e6fd-4b0a-984c-83e6a41390d7/accreditations-iso.jpg) ![Alliant Energy — Renewable Energy Solutions](/assets/logo-IFrgP5Dc.png) Renewable energy & energy-saving specialists. MCS-registered solar PV, battery storage, heat pumps and EV charging across the UK. #### Quick Links - [Home](/) - [About Us](/about-us) - [Services](/services) - [Case Studies](/case-study) - [Areas We Cover](/solar-panel-quotes-north-west) - [Contact](/contact) - [Privacy Policy](/privacy) - [Terms & Conditions](/terms) #### Services - [Solar for Homes](/services/solar) - [Commercial Solar](/services/commercial-solar) - [Battery Storage](/services/battery-storage) - [Air Source Heat Pumps](/services/heat-pumps) - [EV Charging](/services/ev-charging) - [Energy Saving Advice](/services/energy-saving-advice) #### Contact - [01282 501589](tel:01282501589) - [info@alliantenergy.co.uk](mailto:info@alliantenergy.co.uk) - Unit 214 Northlight Industries, Pendle Road, Brierfield, Nelson BB9 5FL [Get a Quote](/quote)[Brochure](/brochure) Alliant Energy Ltd is an Introducer Appointed Representative (Financial Services Register No. 1020779) of Phoenix Financial Consultants Limited (Phoenix). Phoenix is a credit broker, not a lender. Phoenix is authorised and regulated by the Financial Conduct Authority (FRN: 539195), and offers finance from its panel of lenders. All finance subject to status and credit checks. © 2026 Alliant Energy Ltd. All rights reserved. [Privacy Policy](/privacy)[Terms & Conditions](/terms) MCS Registered · TrustMark · NICEIC [Chat with AI](/chat) [Call back](/request-callback) [Get a Quote](/quote) [Get a Brochure](/brochure) [Get a Quote](/quote) [Chat with AI](/chat)