East and West Facing Roofs for Solar PV
A roof that does not face south is not automatically a poor candidate for solar PV. A split east and west array changes when electricity is generated during the day, which can matter as much as how much is generated overall.
An east and west array changes when your solar power arrives
Our main guide to Solar PV already covers the general suitability factors for a roof, including orientation, pitch and shading. This article goes further into one specific case, a roof with no useful south facing slope, where panels are instead split across east and west facing sections, and what that arrangement actually changes for a household.
A different generation shape, not just a smaller total
A single south facing array tends to produce a generation curve that rises through the morning, peaks around the middle of the day, and falls away in the afternoon. A split array, with part of the system facing east and part facing west, produces a flatter, broader curve instead, generating earlier in the morning from the east facing panels and continuing later into the afternoon from the west facing panels, without necessarily reaching as sharp a midday peak.
This matters because the value of solar generation to a household depends heavily on when it is produced relative to when electricity is actually used. A flatter generation curve that stretches further into the morning and afternoon can align better with a household's own usage pattern than a single sharp midday peak does, particularly for a home where daytime use is spread out rather than concentrated around midday.
Self use and export implications
Because a split array spreads generation across more of the day rather than concentrating it around midday, a household with a fairly steady pattern of daytime electricity use may end up using a larger share of its own generation directly, rather than exporting a large surplus in a short midday window. This does not mean an east and west system always generates more electricity overall than a south facing system of the same size, and it does not remove the case for a battery covered in our guide to solar batteries, since a battery remains relevant to any system with surplus generation to store, whatever shape its daily curve takes.
Inverter and design questions to raise
A split array is normally wired as two separate strings, one for each orientation, connected either to a single inverter with two independent input channels, known as maximum power point tracking or MPPT inputs, or to two separate inverters. This matters because a single string that mixes panels of different orientations onto one input can perform worse overall than if the two orientations are correctly separated, since the least favourably positioned panels in a mixed string can hold back the output of the whole string.
When comparing quotations for a split roof, ask specifically how the installer plans to wire the two orientations, whether the inverter has enough independent inputs to keep them separate, and how the proposed panel count and orientation split were decided for your particular roof, rather than accepting a generic assumption about how much each side will contribute.
What to ask an installer about a split east and west roof
- How many panels are proposed for each orientation, and why
- Whether the inverter has separate inputs for each orientation, or whether panels from both sides will share one input
- What shading, if any, affects either side of the roof at different times of day
- Whether the proposed system size still fits sensibly against your own household usage pattern, covered in our main guide's section on choosing the right system size
For general suitability factors, system components, grants and the Solar Payback Explorer, see our guide to choosing a Solar PV system.