Solar Panel Buying Guide + Kit Builder — AIZO Quality Heating

How the kit builder chooses your parts

Every product in the builder is read from our live catalogue when the page opens. If a product sells out it drops out of the builder, and new stock appears as soon as it is published. You can swap any part for another in-stock option, tick or untick additional components and change quantities before sending the whole kit to your basket.

System size and roofs

Set the number of panels on each roof, or let the builder work it out from a target size in kWp or your yearly electricity use. For usage-based sizing we assume around 850 kWh of generation per kWp each year, which is a fair figure for a well-orientated roof across much of the UK. South-facing roofs in the south of England will do better and east–west or shaded roofs will do worse. Each roof is wired as its own string or strings, which sets the number of DC isolators, connectors and cable runs.

Inverter type

The builder asks early whether you want battery storage, because that decides the inverter. Then choose the inverter type. String inverters are the lowest-cost option for a solar-only system on an unshaded roof. Hybrid inverters are battery-ready: add a battery now or later and it charges straight from the panels. Microinverters convert each panel to AC on the roof and suit complex roofs with several small faces. Turn on optimisers with a string or hybrid inverter to add a power optimiser behind each panel, so shade on one panel does not drag down the rest. SolarEdge inverters need SolarEdge optimisers; other inverters are paired with Tigo optimisers.

The builder picks an inverter rated at roughly 75% to 135% of the array size. On a single-phase supply it will also pair a 3.68 kW inverter with an array of up to 160% of its rating, because that keeps the system within G98 and the extra panel output is still useful in the mornings, evenings and winter, or for charging a battery.

Adding a battery

Batteries are offered as complete systems, listed by brand from A to Z. Some brands pair a hybrid inverter with a stand-alone battery, such as Fox ESS EP series or Sunsynk. Stackable systems need several matching parts, and the builder adds them together: Sigenergy SigenStor uses an energy controller, battery modules and a wall or floor mount, and the Sigen SP2 hybrid adds a battery controller; Fox ECS stacks use one Master module with up to six Slaves. The number of modules is sized to your target storage within each system's limits. All-in-one systems that already contain a hybrid inverter are listed as complete systems, so no second inverter is added. With a string inverter or microinverters, the battery connects on the AC side, so the builder only offers AC-coupled batteries and battery inverters. Always check the battery appears on the inverter maker's compatibility list for your exact models before installing.

Additional components

The kit includes a DC isolator for each string, an AC isolator at the inverter (with a second for the backup output on hybrid systems), a generation meter, and a PV warning label pack. With a battery it adds battery hazard labels and a fire alarm for the battery location, as PAS 63100 sets out where home batteries can go and the fire detection expected around them. Brand accessories that suit your inverter or battery are listed unticked, so you can add them if your installer needs them. Your installer designs the final layout and protection against the inverter datasheet and BS 7671.

Cable and connectors

Solar cable is calculated as a red and a black run for each string, using the distance you enter for each roof plus 10% for routing. Runs up to 25 metres use 4 mm² cable and longer runs use 6 mm². Connectors are counted as two pairs per string. For microinverters the builder adds the brand's own parts from its installation guide instead: the AC trunk cable or M-Cable with one connector per microinverter, an end cap or terminator for each branch, and the gateway or controller the system needs to start up. Branches are sized to the manufacturer's limits, for example up to 11 Enphase IQ8MC or 7 Atmoce MI-500 on a 20 A branch.