# Solar Savings Calculator — United Kingdom

> Estimate the financial effect of a specified rooftop solar scenario, with exported electricity valued separately from electricity used in the home. GBP planning view; stated limitations apply.

Page: https://askcalculators.com/uk/solar-savings/
Definition: https://askcalculators.com/uk/solar-savings/definition.json
JSON Schema: https://askcalculators.com/uk/solar-savings/schema.json
Version: 20.16.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/uk/solar-savings/?annualUse=10000&offset=80&specificYield=1200&selfConsumption=60&importRate=0.2&exportRate=0.05&installedCostPerKw=2500&confirmedIncentive=0&maintenance=100&years=25&discountRate=4&degradation=0.5&energyEscalation=2&replacementYear=0&replacementCost=0

## Inputs
- annualUse: Annual household electricity use, kWh; type=number; required; default=10000; min=1; max=100000000
- offset: Target annual generation / use; type=percent; required; default=80; min=0; max=300
- specificYield: Site-specific annual yield, kWh per kW; type=number; required; default=1200; min=100; max=3000
- selfConsumption: Generation used directly on site; type=percent; required; default=60; min=0; max=100
- importRate: Avoided electricity price per kWh; type=money; required; default=0.2; min=0; max=1000000000000
- exportRate: Confirmed export payment per kWh; type=money; required; default=0.05; min=0; max=1000000000000
- installedCostPerKw: Installed cost per kW; type=money; required; default=2500; min=0; max=1000000000000
- confirmedIncentive: Confirmed eligible incentive; type=money; required; default=0; min=0; max=1000000000000
- maintenance: Annual maintenance allowance; type=money; required; default=100; min=0; max=1000000000000
- years: Planning horizon, years; type=number; required; default=25; min=1; max=50
- discountRate: Annual discount rate; type=percent; required; default=4; min=0; max=50
- degradation: Annual output degradation; type=percent; required; default=0.5; min=0; max=20
- energyEscalation: Annual energy-price escalation; type=percent; required; default=2; min=0; max=25
- replacementYear: Replacement year (0 means none); type=number; required; default=0; min=0; max=50
- replacementCost: Replacement cost; type=money; required; default=0; min=0; max=1000000000000

## Outputs
- sizeKw: Target DC system size, kW; format=number
- generation: First-year generation, kWh; format=number
- selfConsumed: On-site use of generation, kWh; format=number
- exported: Exported generation, kWh; format=number
- capital: Net capital cost; format=currency
- annualSaving: First-year net saving; format=currency
- payback: Simple payback, years; format=number; primary
- npv: Discounted net value; format=currency
- breakeven: Cash-flow break-even year; format=number
- cumulative: Undiscounted lifetime net benefit; format=currency

## Formula
kW = annual use × target offset ÷ specific yield; net benefit = self-used kWh × avoided rate + exported kWh × export rate − maintenance.

Inputs are converted to canonical units before evaluating this stated formula.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: Illustrative defaults are not local quotes or verified legal rules. Dated reference components and user-entered assumptions are explicitly distinguished. Professional review is pending.