June 30, 2026 · 4 min read · HSB Renewable Energy
The instinct is to fill the roof, but the better question is what you use and when. As orientation: a two-bed terrace usually takes around six panels at 2.5kW, a three-bed semi nine to ten panels at 4kW, and a detached house or farmhouse twelve or more, often with a battery alongside.
Orientation and shading matter more than most people expect. South is best, but east-west arrays spread generation across the morning and evening, which can suit a household that is out in the middle of the day better than a single south-facing block.
Plan for what is coming, not just what is here. If an electric car or a heat pump is on your horizon in the next few years, sizing for that now is far cheaper than adding to an array later, and it changes which inverter makes sense today.
Commercial roofs are a different exercise again: those are designed to the building and its load profile, and priced after a survey rather than from a table.
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