How Much Solar Does a Castleford Roof Make in January? The PVGIS Figures, Month by Month

ElectriFusion Solutions · 15 October 2026

January is the month that decides whether a home battery in Castleford earns its keep from the roof or from the tariff. Below is every month for a south-facing Castleford roof, from the European Commission's PVGIS model, and what each one means for a 5 kWh and a 10 kWh battery.

A 4.85 kW array in Castleford, every month

PVGIS 5.2, SARAH2 radiation database, Castleford town-centre coordinates, south-facing at 35°, 14% system losses, fetched 15 October 2026. Annual total 4,665 kWh (962 kWh per kW), about 1.9% less than Doncaster. Modelled averages, not a guarantee for any particular roof.

The best month here is May at 588 kWh (19.0 kWh a day) and the worst is Dec at 157 kWh (5.1 kWh a day), a ratio of 3.7 to one; that ratio, not the annual total, is what a battery has to live with.

For scale: PVGIS puts the in-plane irradiation on that roof at about 1,183 kWh per square metre a year, and the array converts it to 962 kWh per installed kilowatt; a Castleford household with the regional average evening load would see the battery cycle fully on about 214 days a year on these figures.

What that means for the battery

Rule of thumb: a 5 kWh battery fills from the roof on a 10 kWh day, a 10 kWh battery on a 16 kWh day, once the house has used its daytime share. For Castleford the first is true on average in Mar, Apr, May, Jun, Jul, Aug, Sep and the second in Apr, May, Jun, Jul, Aug.

From November to January the average is 5.7 kWh a day. A house that runs a fridge, a router, a kettle and some lighting through the day uses most of that as it arrives, so the battery sees a few hundred watt-hours of surplus, not five kilowatt-hours. That is not a fault with the battery or the panels; it is the latitude.

That something else is the grid

On a time-of-use tariff the battery charges in the cheap overnight window and discharges into the evening peak, every day of the year, solar or not. In the dark months that is the whole of its job in Castleford; in summer it is a top-up, because the roof has already filled it. The saving is the rate gap times the kilowatt-hours shifted, so ask for the tariff's night and peak rates before the battery's brochure.

One caution: do not add grid-charging savings on top of solar savings for the same day. A battery that charged overnight is already full when the morning surplus arrives, so the summer saving is one or the other.

So what size for a Castleford home?

Measure the evening. The kilowatt-hours used between the panels switching off and bedtime are what the battery has to cover, and a smart meter's half-hourly export tells you in a week. In Castleford a typical three-bedroom semi lands at 5 kWh; a larger house with an EV or a heat pump justifies 10 kWh, mostly for the overnight charging rather than the roof. The sizing and registration details are on our battery storage Castleford page, and the panels themselves on solar panels in Castleford.

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