The fundamentals: what the numbers mean, what the equipment does, what the grid rules require, and what maintenance actually involves.
These pages exist because the same handful of questions decide whether solar makes sense for a particular house, and the answers are almost always given as rules of thumb rather than as figures. Where we can put a number on something we do, from data we generated ourselves and publish alongside the page.
Fourteen pages are published, and the generation dataset behind them is free to download. Equipment and maintenance are next, and each ships only when its figures can be sourced and cited properly rather than summarised from somewhere else.
If there is something specific you were looking for, tell us — it moves up the queue.
Most people start here
Self-consumption: the number that decides whether solar pays
A unit you use is worth 26p; the same unit exported is worth 4p. MCS's own method puts a typical household at 14–23% — far below what most calculators assume, including, until we checked, ours.
Shading: how much output you really lose
Fifteen scenarios modelled. A building due south costs 2% of summer output and 75% of winter output. The same obstruction due north costs nothing at all.
kWp vs kWh: the two solar numbers
A quote is priced in kWp, your bill is charged in kWh, and only one of them decides whether solar is worth it. The number that connects them, published for 25 UK locations.
Core concepts
Certification and the grid
Roofs and geometry
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