Off-Grid Solar Systems UK: Complete Guide
Everything you need to know about going off-grid with solar power in the UK — from system sizing and costs to whether it's actually worth it for your property.
Quick Answer
An off-grid solar system generates and stores all the electricity your property needs without any connection to the National Grid. A typical UK home needs a 5kW+ panel array, 20–40kWh battery bank, a hybrid inverter, and a backup generator for winter — costing £20,000–£30,000 in 2026. Off-grid solar rarely makes financial sense for homes that already have a grid connection, but it is ideal for remote properties, farms, holiday cabins, and canal boats.
What is an off-grid solar system?
An off-grid solar system is a self-contained power setup that is completely disconnected from the National Grid. Your solar panels generate electricity during the day, a battery bank stores the surplus, and you draw from those batteries at night or during cloudy periods.
Unlike a standard grid-tied system — where excess energy is exported to the grid and you draw power back when needed — an off-grid system must produce and store all the electricity you use. There is no grid to fall back on.
This means off-grid systems are significantly larger and more expensive than grid-tied equivalents. You need oversized panels to generate enough energy even in winter, a large battery bank to cover multiple days of low sunlight, and typically a backup generator for extended cloudy periods.
Key difference from grid-tied solar
A grid-tied system uses the grid as a “virtual battery” — you export surplus during the day and import at night. An off-grid system replaces the grid entirely with physical battery storage and a backup generator. This is why off-grid costs 2–3× more than a standard solar installation of the same panel capacity.
Off-grid vs on-grid vs hybrid solar systems
There are three main types of solar system. Here's how they compare for UK homes:
| Feature | On-Grid | Hybrid | Off-Grid |
|---|---|---|---|
| Grid connection | Yes | Yes | No |
| Battery storage | Not required | Yes (5–15kWh) | Yes (20–40kWh+) |
| Power in outages | No | Yes (limited) | Yes (full) |
| Export income (SEG) | Yes (3–15p/kWh) | Yes (3–15p/kWh) | No |
| Typical cost (4kW) | £6,000–£8,000 | £10,000–£14,000 | £20,000–£30,000 |
| Best for | Most UK homes | Homes wanting backup | Remote / off-grid properties |
| Backup generator | Not needed | Optional | Strongly recommended |
| Complexity | Simple | Moderate | Complex |
For most UK homes with an existing grid connection, a standard on-grid or hybrid system is the most cost-effective choice. Off-grid makes sense primarily when there is no grid connection available or the cost of connecting to the grid exceeds £20,000+.
Off-grid solar system components
A complete off-grid solar system has five core components. Each must be correctly sized to meet your energy needs year-round, including through the UK's low-output winter months.
Solar Panels
The primary energy source. Off-grid systems typically need 5–10kW+ of panels — more than a grid-tied system of the same home size — to compensate for winter shortfall and battery charging losses.
Charge Controller
Regulates the flow of electricity from the panels to the batteries. MPPT (Maximum Power Point Tracking) controllers are standard for off-grid systems, offering 95–99% efficiency vs 75–80% for cheaper PWM controllers.
Battery Bank
Stores energy for use at night and during cloudy days. Off-grid homes need 20–40kWh+ of usable capacity. Lithium iron phosphate (LiFePO4) batteries are the current standard, lasting 10–15 years with 6,000+ cycles.
Off-Grid Inverter
Converts DC power from the batteries to AC power for your household appliances. Off-grid inverters also manage the battery charging cycle and load distribution. Popular brands include Victron, SMA Sunny Island, and Studer.
Backup Generator
Essential for UK off-grid systems. During December and January, solar output can drop to 10–15% of summer levels. A diesel or LPG generator covers extended low-sunlight periods and prevents deep battery discharge.
Monitoring System
Tracks solar generation, battery state of charge, and energy consumption in real time. Critical for off-grid systems where running out of power means no power at all. Most inverters include built-in monitoring via an app.
How much does an off-grid solar system cost?
Off-grid solar costs vary significantly depending on your energy needs, battery capacity, and location. Here are typical 2026 prices for complete off-grid systems including installation:
| Property Type | System Size | Battery Capacity | Total Cost |
|---|---|---|---|
| Small cabin / shepherd's hut | 1–2kW | 5–10kWh | £8,000–£12,000 |
| Average home (3-bed) | 5–7kW | 20–30kWh | £20,000–£30,000 |
| Large property / farmhouse | 10kW+ | 40–60kWh+ | £40,000–£60,000 |
Cost breakdown for a typical 5kW off-grid system
| Component | Cost |
|---|---|
| Solar panels (5kW, 12 panels) | £3,000–£4,500 |
| Battery bank (25kWh LiFePO4) | £8,000–£12,000 |
| Off-grid inverter + charge controller | £2,500–£4,000 |
| Backup generator (diesel/LPG) | £1,500–£3,000 |
| Wiring, mounting, BOS | £1,500–£2,500 |
| Installation labour | £3,000–£5,000 |
| Total | £19,500–£31,000 |
Prices include 0% VAT on solar panels and batteries (extended to 2026 for residential installations). Generator and some BOS components may attract standard 20% VAT. All prices are estimates and will vary by installer, location, and system specification.
Is off-grid solar worth it in the UK?
The honest answer: for most UK homes with an existing grid connection, off-grid solar rarely makes financial sense. A standard 4kW grid-tied system costs £6,000–£8,000 and pays for itself in 6–8 years. An off-grid system for the same home costs £20,000–£30,000 and you lose Smart Export Guarantee income.
The UK's climate is the main challenge. Between November and February, solar output drops to 10–20% of summer levels. An off-grid system must be oversized to cope, and you'll still need a backup generator for extended cloudy periods in winter.
Off-grid solar makes sense for
- ✓Remote properties — where grid connection costs £20,000+ or is not available
- ✓Farms and rural buildings — barns, outbuildings, and field shelters
- ✓Holiday cabins and lodges — seasonal use reduces winter concerns
- ✓Canal boats and houseboats — no grid connection possible
- ✓Self-sufficiency priority — energy independence matters more than payback
Off-grid solar does not make sense for
- ✗Grid-connected homes — grid-tied solar is 2–3× cheaper with faster payback
- ✗Urban properties — reliable grid, limited roof space, no generator room
- ✗High-consumption homes — electric heating, EV charging, or home offices increase battery needs dramatically
- ✗Pure cost savings — the payback period for off-grid exceeds 15–20 years in most cases
The UK winter problem
In December and January, a south-facing 5kW system in the Midlands generates roughly 3–5kWh per day — compared to 20–25kWh in June. The average UK home uses 8–10kWh per day. This means you'll need either a very large battery bank (and accept deep cycling), a backup generator, or a combination of both to get through winter. This is the single biggest challenge for off-grid solar in the UK.
Sizing your off-grid solar system
Correctly sizing an off-grid system is critical. Too small and you'll rely heavily on your generator; too large and you waste money on unused capacity. Here's how to calculate what you need:
Step 1: Calculate your daily energy consumption
Add up the wattage of every appliance multiplied by hours of daily use. The average UK household uses 8–10kWh per day, but off-grid homes tend to be more energy-conscious (5–8kWh).
| Appliance | Watts | Hours/Day | kWh/Day |
|---|---|---|---|
| LED lighting (whole house) | 100W | 6 | 0.6 |
| Fridge-freezer | 150W | 24 | 1.5 |
| Washing machine | 500W | 1 | 0.5 |
| Laptop + router | 80W | 10 | 0.8 |
| Cooking (induction hob) | 2,000W | 1 | 2.0 |
| TV + entertainment | 100W | 4 | 0.4 |
| Water pump | 300W | 2 | 0.6 |
| Total | ~6.4kWh |
Step 2: Size your solar panel array
In the UK, a 1kW solar array generates an average of 2.5–3.0kWh per day across the year (less in winter, more in summer). For off-grid, you should size for worst-case winter output — roughly 1.0–1.5kWh per kW per day in December. For 6.4kWh daily use, you'd need at least 5–7kW of panels, assuming generator backup covers the deepest winter shortfall.
Step 3: Size your battery bank
A common rule is 2–3 days of autonomy — enough stored energy to cover 2–3 days without sun before the generator kicks in. For 6.4kWh daily use, that means 13–19kWh usable capacity. With a 90% depth of discharge on lithium batteries, you'd need a 15–22kWh battery bank. Most off-grid homes install 20–30kWh for comfort.
Step 4: Choose your backup generator
A 3–5kW diesel or LPG generator is standard for a typical off-grid home. It should be able to power your essential loads whilst simultaneously charging the batteries. Budget £1,500–£3,000 for a quality unit. Plan for 200–500 hours of generator run time per year, primarily in December and January.
Planning permission for off-grid solar
Solar panels on residential properties in England, Scotland, and Wales generally fall under permitted development — meaning no planning permission is needed — provided they meet certain conditions:
- Panels do not protrude more than 200mm from the roof surface
- Panels do not extend above the highest point of the roof (excluding the chimney)
- The property is not a listed building or in a conservation area (additional rules apply)
- Ground-mounted arrays do not exceed 9m² in area and 4m in height
For off-grid properties, there are additional considerations:
- Ground-mounted arrays — larger off-grid systems often use ground-mounted panels. Arrays over 9m² require planning permission.
- Battery storage — large battery banks in separate outbuildings may need building regulations approval for fire safety and ventilation.
- Generator housing — a permanent generator enclosure may require planning permission depending on size and location.
- Agricultural land — solar installations on agricultural land may have additional planning requirements under agricultural permitted development rights.
Always check with your local planning authority before installing. See our planning permission guide for full details.
Frequently Asked Questions About Off-Grid Solar
Can you go fully off-grid with solar in the UK?
Yes, but it requires a large system (5kW+ panels, 20–30kWh battery bank) and a backup generator for winter. The UK's low winter sunlight means solar alone cannot reliably power a home year-round. Most off-grid homes use a diesel or LPG generator for 200–500 hours per year to cover December–January shortfalls.
How much does an off-grid solar system cost in the UK?
A complete off-grid system for an average UK home costs £20,000–£30,000 in 2026. This includes 5–7kW of solar panels, a 20–30kWh battery bank, an off-grid inverter, and a backup generator. Small cabins can be set up for £8,000–£12,000, while large properties may exceed £40,000–£60,000.
What is the difference between off-grid and on-grid solar?
On-grid (grid-tied) solar is connected to the National Grid — you export surplus energy and import when needed. Off-grid solar is completely independent with no grid connection. On-grid is cheaper (£6,000–£8,000 vs £20,000–£30,000), simpler, and earns Smart Export Guarantee income. Off-grid provides complete energy independence but requires batteries and a backup generator.
How many solar panels do I need to go off-grid?
For a typical UK home using 8–10kWh per day, you need 12–16 solar panels (5–7kW total) for off-grid. This is more than the 10–12 panels needed for a standard grid-tied system, because you need to generate enough surplus to charge batteries and compensate for winter shortfall.
What size battery do I need for off-grid solar?
A typical off-grid UK home needs 20–30kWh of battery storage — enough for 2–3 days of autonomy without sun. This is significantly more than the 5–10kWh battery used in grid-tied hybrid systems. Lithium iron phosphate (LiFePO4) batteries are the standard choice, lasting 10–15 years.
Do I need planning permission for off-grid solar?
Roof-mounted solar panels generally fall under permitted development. However, off-grid systems often include ground-mounted arrays (planning needed if over 9m²), battery housing (may need building regulations approval), and generator enclosures (may need planning). Check with your local planning authority.
Is off-grid solar worth it financially?
For homes with an existing grid connection, off-grid solar rarely makes financial sense — the payback period exceeds 15–20 years. It is worth it when grid connection costs exceed £20,000 (common for remote rural properties), or when energy independence is a priority regardless of payback.
What happens in winter with off-grid solar?
Winter is the biggest challenge for off-grid solar in the UK. In December, a 5kW system in the Midlands generates only 3–5kWh per day, compared to 20–25kWh in June. A backup generator is essential to cover the shortfall, typically running 200–500 hours over the winter months.
Related Guides
Battery Storage
Solar battery costs, sizing, popular models, and payback analysis.
Solar Panel Costs
Full cost breakdown and payback periods.
Planning Permission
Permitted development, listed buildings, and when you need to apply.
Solar Panels in Winter
Winter output data, monthly breakdown, and performance tips.
Sources
- Energy Saving Trust — Solar Panels — energysavingtrust.org.uk
- Ofgem — Smart Export Guarantee — ofgem.gov.uk
- MCS — Microgeneration Certification Scheme — mcscertified.com
- Planning Portal — Solar Panels Permitted Development — planningportal.co.uk
- PVGIS — Photovoltaic Geographical Information System — re.jrc.ec.europa.eu
Last updated: March 2026
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He fact-checks all content against official MCS and Ofgem data and maintains relationships with MCS-certified installers across the UK.
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