A simple, practical guide to choosing the right solar system size for your home, business or farm — based on NI usage, roof size and real 2026 savings.
Updated for 2026 • Northern Ireland Specific
Most homes in NI fall into these ranges. Find what matches your situation.
Flats, terraces, or 1-2 bed homes with modest electricity usage.
Semi-detached or terraced homes with normal family usage.
Detached homes with higher electricity needs.
Homes with electric vehicles or high appliance usage.
Businesses and farms scale far higher — see the section below for commercial system sizes.
There are two things you need to know to size your solar system correctly.
This is the biggest factor in determining your system size. You'll find it on your NIE Networks bill.
More usage = bigger system required
Roof direction significantly affects how much electricity your panels will generate.
Most NI panels are ~1.7m² each
Find your property type and usage level to determine the ideal system size.
| Property Type | Usage | System Size | Panels Needed |
|---|---|---|---|
|
2-Bed Terrace
|
Low | 3 kW | 8–10 |
|
3-Bed Semi-Detached
|
Medium | 4 kW | 10–12 |
|
4-Bed Detached
|
High | 5–6 kW | 12–16 |
|
Home with EV
|
Very High | 6–8 kW | 14–20 |
Pro tip: If your goal is maximum bill reduction, go toward the higher end + add a battery for optimal savings.
Your roof orientation affects energy output — here's how to compensate.
Your system can be smaller — this is the ideal orientation
Very good — add 1 extra panel if needed
Add 1–3 extra panels to compensate
Not suitable for solar — consider a different roof
A professional installer will use satellite imagery and yield calculations to determine the exact system size for your specific roof orientation. They'll ensure you get the optimal number of panels for maximum savings.
For most NI homes — yes, absolutely. Here's why.
Use your free electricity when you need it most — in the evening.
Get more from your system by using solar when it's not generating.
Watch your electricity bills drop dramatically.
Charge your electric car using stored solar for almost nothing.
Best for couples or small homes with modest evening usage.
The most popular choice for average family homes.
Perfect for larger families with electric vehicles.
Batteries reduce grid reliance and speed up your payback time significantly.
Businesses and farms in NI can install much larger systems with faster payback.
Shops, salons, cafés
Office units, small warehouses
Large commercial units
Northern Ireland agriculture is a perfect fit for solar. Farms often have:
Typical farm systems: 50–100 kW+
Actual costs and savings for typical NI solar installations.
With rising energy prices, solar payback is faster than ever.