Solar Calculators
Single-purpose sizing tools for solar and off-grid systems: rooftop, RV, boat, cabin and tiny home. Every page shows the formula and a worked example.
Solar System Size Calculator
What size solar system you need in kW, from daily kWh use, peak sun hours and system losses
Open CalculatorPlug-in Solar Savings Calculator
What a UK plug-in or balcony solar kit saves a year, including the generation you spill to the grid unpaid
Open CalculatorUK Solar Map
How much sun every postcode gets, and what an 800 VA plug-in kit makes there on a roof or a balcony, from PVGIS satellite data
Open CalculatorWorld Solar Map
Where the sun is right now, how much a panel makes anywhere on Earth, and which countries let you plug a kit into a socket
Open CalculatorSun Path Calculator
The sun's track across your sky on any date, and exactly when a tree, chimney or neighbouring roof puts your panels in shade
Open CalculatorOff-Grid Load Calculator
Add up every appliance to get daily watt-hours, amp-hours and the peak load your inverter has to carry
Open CalculatorBattery Bank Size Calculator
Battery bank capacity in Ah and kWh from daily use, days of autonomy, depth of discharge and temperature
Open CalculatorBattery Bank Runtime Calculator
How long a battery bank lasts from capacity, system voltage, depth of discharge and load
Open CalculatorCharge Controller Sizing Calculator
Amp rating for an MPPT or PWM solar charge controller, with the array-watt limit at 12V, 24V and 48V
Open CalculatorInverter Sizing Calculator
Continuous and surge inverter rating from your load, plus the DC input current the battery cable has to carry
Open CalculatorSolar Panel Series vs Parallel Calculator
Array voltage and current for any series and parallel arrangement, including cold-weather Voc
Open CalculatorSolar Panel Output Calculator
Daily, monthly and annual kWh from an array you already have, with cell temperature handled separately
Open CalculatorSolar Payback Calculator
Payback period, lifetime saving and ROI from install cost, incentives, export rate and tariff inflation
Open CalculatorDC Voltage Drop Calculator
Voltage drop on 12V, 24V and 48V DC runs by cable length, current and conductor size
Open CalculatorSolar Cable Size Calculator
Smallest DC cable that carries the current and stays inside your voltage-drop limit (AWG/mm2)
Open CalculatorAWG to mm2 Conversion Calculator
Convert AWG to mm2, circular mils, kcmil and diameter for PV and battery cable
Open CalculatorPV Fuse and Breaker Sizing Calculator
Next standard fuse or breaker size for a PV string, controller or inverter circuit
Open CalculatorEnergy Cost Calculator (kWh)
What an appliance or a whole load costs to run, and what solar offsets it saves
Open CalculatorWatt Hour Calculator
Watts and hours to Wh and kWh, and amp-hours either way at 12V, 24V or 48V
Open Calculator
Solar Sizing Calculator
Free solar and off-grid sizing calculators
Tools
- Solar System Size Calculator
- Plug-in Solar Savings Calculator
- UK Solar Map
- World Solar Map
- Sun Path Calculator
- Off-Grid Load Calculator
- Battery Bank Size Calculator
- Battery Bank Runtime Calculator
- Charge Controller Sizing Calculator
- Inverter Sizing Calculator
- Solar Panel Series vs Parallel Calculator
- Solar Panel Output Calculator
- Solar Payback Calculator
- DC Voltage Drop Calculator
- Solar Cable Size Calculator
- AWG to mm2 Conversion Calculator
- PV Fuse and Breaker Sizing Calculator
- Energy Cost Calculator (kWh)
- Watt Hour Calculator
- All Tools
Guides
Resources
More Calculators
- Electrical Calculators AC wiring, voltage drop and cable sizing tools
- Flow Rate Calculator Pump, pipe and flow rate tools
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