Solar panels for detached houses: what to know before buying

Buying solar panels for a detached house is many people’s first contact with solar energy, and there are usually plenty of questions. The good news is that most of what affects the decision becomes clear with a few basic questions. This guide covers what is worth checking before buying, so you can compare offers and decide at your own pace.

1. The roof: orientation, pitch and condition

The roof is the foundation of a solar system. A south-facing roof is often the most productive, but southeast, southwest and east–west roofs are also well suited – an east–west roof spreads production more evenly across morning and evening. Pitch, roofing material and the age of the roof affect installation. If the roof needs replacing in the next few years, that is worth factoring into the timing. Shading trees, chimneys and neighbouring buildings also affect production and are taken into account in the design.

2. Electricity use and its timing

You get the most from solar electricity when production coincides with consumption. So it is useful to know your annual consumption and when electricity is mainly used. The heating method matters a lot: an air-source heat pump, a hot water tank or EV charging increase daytime use and improve the self-consumption rate. If you do not know your consumption precisely, that is fine – an estimate is enough to start.

3. System sizing

The right size is not the largest possible one but the one that suits the property. A system that is too small leaves benefit on the table; one that is too large produces surplus that earns a lower compensation. Sizing is based on consumption, the roof and your goals. A good starting point is to size the system so that a large share of production goes to your own use.

4. Components and warranties

It is worth paying attention to the following:

• Panel quality and the manufacturer’s power warranty, which is often around 25 years
• The quality and warranty of the inverter – its lifespan is typically shorter than the panels’
• Mounting systems and their suitability for the roofing material
• The warranty on the installation work and who is responsible for the whole
• The option to add a battery or expand the system later

5. A battery now or later?

A battery is not a mandatory part of a solar system; it is a natural upgrade that can be added later. A battery increases the use of your own production by storing daytime surplus for the evening and night. Its profitability depends on the consumption profile, so for many a sensible approach is to start with panels and assess the need for a battery later. Note also that not all battery systems automatically provide backup power during a grid outage.

6. The purchasing process and permits

A clear process moves from assessment to design, an offer, installation and commissioning. A grid-connected system requires an agreement with the local grid company, and the installation should be carried out by a professional. When you request offers, make sure they are comparable: do they include design, installation, commissioning and warranties?