Solar calculator

Your solar savings.

See how much your panels could save at home, earn from exported energy, and deliver over a month or a year.

The daylight window 6 hours

Useful daylight hours used in the estimate.

01 — Your setup

A few figures.

Solar panel capacity System size

For example, 4.000 kW = 4,000 W.

Average effective output Real-world average

Real-world average output during Solar times.

Solar times Daily solar window

24-hour time; for example 10:00–15:00. An earlier end time means the range crosses midnight.

Solar output hours Calculated

hours

Calculated from Solar times.

Home demand profile Used with or without a battery

Set typical peak and off-peak use and the times for each period. These figures estimate total home use and solar-only savings; the battery adds its own effect only when included.

Home use during peak windows Average per hour

kWh/h

Average demand during both peak windows; included in solar-only usage and battery estimates.

Off-peak home use Average per hour

kWh/h

Average demand outside both peak windows; used for solar self-use, total home use and battery supply.

Morning peak times Peak-use window

24-hour time; for example 07:00–09:00. An earlier end time means the range crosses midnight.

Morning peak hours Calculated

hours

Calculated from Morning peak times.

Evening peak times Peak-use window

24-hour time; for example 15:00–18:00. An earlier end time means the range crosses midnight.

Evening peak hours Calculated

hours

Calculated from Evening peak times.

Standard import tariff Solar + battery savings

/ kWh

25p = £0.25/kWh; also values battery supply outside Charge times.

Feed-in tariff Rate paid for exported energy

/ kWh

12p = £0.12 / kWh

Solar purchase costs Up-front spend

Enter the total solar purchase and installation cost.

Surplus solar power Calculated

2.2 kW

Surplus solar after home usage

03 — Daily total savings

↑

£2.57

Home-use savings plus earnings from surplus energy exported in one day.

The quick breakdownPER DAY · £ + kWh

Solar used at home1.000 kW

Grid cost × output hours£0.25 / kWh × 5 hrs

Surplus solar power2.200 kW

Feed-in earnings£1.32

Solar-only savings£2.57

Battery net saving / costOff

Total battery charge inputOff

Total savings£2.57

Home savings = solar power used (kW) × grid cost (£/kWh) × solar hours(1.000 × £0.25 × 5)Feed-in earnings = surplus power (kW) × feed-in tariff (£/kWh) × solar hours(2.200 × £0.12 × 5)

02 — Optional battery

Store energy for home use.

Include battery in totals

Battery off; battery charge energy and purchase cost are excluded from totals.

Solar serves daytime home use first. With Solar first, surplus charges the battery before export; with Grid only, surplus is exported and the battery charges from the grid. When included, the battery adds supply to the peak and off-peak demand profile set in Your setup, outside Charge times and within its reserve, target and power limits. The discounted grid-charge rate applies only during Charge times.

Battery capacity Storage size

kWh

Example value—replace it with your installed capacity.

Battery purchase costs Up-front spend

Enter the total battery purchase and installation cost.

Minimum discharge Battery reserve

Battery won't discharge below this reserve; the estimate assumes it starts at this level.

Target charge After charging

Must be at least the starting charge.

Charge times Grid charge / top-up window

24-hour time; for example 23:00–02:00 crosses midnight.

Charge-time hours Calculated

hours

Calculated from Charge times; this window limits grid charging and top-up.

Grid charging tariff Charge-window rate only

/ kWh

Default: £0.07/kWh. Applies only to grid energy used during the configured Charge times.

Charge/discharge power Maximum rate

Enter 0.1–10 kW; the same limit applies when supplying home use outside Charge times.

Charging strategy Source order

Battery calculations are off; the solar-only estimate is unchanged.

Selected charging strategy — Enable the battery estimate to calculate the charge percentage.

Cost to charge — Enable the battery estimate to calculate charging cost. Enable the battery estimate to estimate charging time.

Battery energy to home—

Grid import cost avoided—

Charge after home use——

Net battery saving / cost—

04 — Potential savings

Your longer-term picture.

Home demand includes peak and off-peak hours. Grid use adjusts for solar and battery flows; Quick breakdown shows total battery charge input. Extra grid kWh can still save money at cheaper tariffs. Payback uses included costs ÷ annual savings.

One day£2.57

Estimated savings

Total grid kWh used—

Grid kWh saved—

30 days£0.48

Estimated savings over 30 days

Total grid kWh used—

Grid kWh saved—

One year£5.78

Estimated savings over 365 days

Total grid kWh used—

Grid kWh saved—

Total purchase costs£0.00

Solar + included battery

Investment payback—

Years at the estimated annual savings rate

05 — Energy schedule

A day at a glance.

A 24-hour timeline of Solar and Charge times plus Morning and Evening peaks. The battery supplies peak and off-peak demand outside Charge times; morning use is subtracted before the evening estimate.

Solar generation & home use —

Off peak home usage —

Battery charging —

Morning peak home usage —

Battery discharge · morning —

Evening peak home usage —

Battery discharge · evening —

Bars show scheduled time windows rather than energy volume. Peak periods are red; crosshatching marks estimated hours actually used for grid charging, starting at the beginning of Charge times. Surplus solar is applied first during Solar times; Morning discharge uses battery energy first, with only the remaining surplus available for the Evening peak.