Home Solar System Sizer
Estimate the solar PV capacity, approximate panel count, preliminary inverter size, optional battery capacity and annual energy coverage for your home.
This tool is under active development. PV system sizing, panel count, preliminary inverter planning, and preliminary battery sizing are now available. Detailed production modeling will be added in a future step.
What type of solar system are you planning?
Your Electricity Consumption
Enter your household electricity use in kWh. Do not use currency or bill amounts.
Enter your average monthly electricity consumption in kWh. You can find this on your electricity bill.
Your Location
Used to estimate solar resource. We do not require your street address.
Your location helps estimate available solar irradiation. Precise address is not needed.
Your location does not drive PV sizing yet. Enter your solar resource manually in the Solar Resource section below. Location-based estimation will be integrated in a future step.
Your Energy Goals
What do you want to achieve with your solar system?
What percentage of your annual consumption should solar cover? This is a planning target, not a guarantee.
Solar Resource
Enter the annual specific yield for your location. This is the primary solar-resource input for PV sizing.
This represents the estimated annual electricity generated by 1 kWp of installed solar capacity at your location. You can obtain this value from a trusted solar-resource calculator, an installer estimate, or another reliable location-specific solar source.
This field is required.
This is a manual planning input. The system does not automatically derive this value from your location.
Panel & Inverter Planning
Choose your panel wattage and target DC/AC ratio for preliminary equipment planning.
Enter the rated power of a single solar panel in watts. This is a planning input — no specific panel brand or model is assumed.
This field is required.
DC/AC ratio compares the nominal DC solar-array power with the inverter's AC power rating. A common planning starting point is 1.2, but the final allowable ratio depends on the inverter manufacturer, module configuration, climate, and local rules.
The final allowable ratio depends on inverter manufacturer limits, module configuration, climate, local rules, and installer design. 1.2 is not universally correct.
Installation Context
Basic installation information. No structural engineering calculations.
Optional. Helps check physical feasibility later. Enter the usable area, not total roof area.
Electrical Supply
Optional technical context for future inverter guidance. Unknown is a valid answer.
This will help guide inverter selection in a future step. If you're unsure, select "I don't know".
Enter your consumption, target coverage, and annual specific yield to calculate.
This tool provides planning estimates only. It does NOT replace a qualified solar installer, licensed electrician, structural assessment, local permitting, or utility/interconnection review. Do NOT use this tool for final string design, wire sizing, overcurrent protection, grounding, breaker selection, MPPT wiring, or grid interconnection design.
How the Home Solar System Sizer Works
The calculator follows a deterministic planning flow:
- 1.Enter your electricity consumption in kWh.
- 2.Choose your target annual solar coverage.
- 3.Enter the annual specific solar yield for your location.
- 4.Select your solar panel wattage.
- 5.Review the recommended PV system size and estimated panel count.
- 6.Review the preliminary inverter AC size.
- 7.Add battery or autonomy assumptions where relevant.
- 8.Review estimated annual solar production and annual energy balance.
What the Calculator Estimates
This planning calculator can estimate:
- •Recommended planning PV size in kWp
- •Estimated panel count based on selected panel wattage
- •Actual planning DC array after whole-panel rounding
- •Preliminary inverter AC size for on-grid and hybrid systems
- •Preliminary battery capacity for hybrid and off-grid systems
- •Estimated annual solar production in kWh
- •Annual production-to-consumption ratio
- •Annual energy coverage ceiling
- •Annual energy surplus or deficit indicator
All values are planning estimates, not final engineering values.
Understanding Solar System Size
These units are often confused but measure different things:
PV system size is measured in kWp, inverter size in kW, and energy production or consumption in kWh.
Solar Panels and DC Array Size
The estimated panel count is calculated by dividing the recommended PV size by the selected panel wattage. Because the number of panels must be a whole number, the calculator rounds upward. This can make the actual DC array slightly larger than the original planning target.
Roof Fit Boundary
The estimated panel count does not confirm that the panels physically fit on your roof. Final layout depends on module dimensions, roof dimensions, orientation, obstructions, setbacks, shading, and structural considerations. No generic panel dimensions are assumed.
Preliminary Inverter Sizing
On-grid and hybrid inverter planning uses the actual DC array and a user-visible target DC/AC ratio. The result is preliminary. Final inverter selection depends on manufacturer limits, electrical phase, panel configuration, grid requirements, and installation design.
Home Battery Sizing
Battery sizing estimates energy capacity in kWh based on hybrid backup requirements or off-grid autonomy requirements. Battery energy capacity (kWh) is different from battery output power (kW). The two are not interchangeable.
Annual Solar Production and Energy Coverage
Estimated annual PV production is calculated by multiplying the actual planning DC array by the annual specific solar yield. No hidden efficiency or loss factor is applied. The annual specific yield is currently a manual planning input.
The production-to-consumption ratio compares total annual PV production with annual consumption. The annual energy coverage ceiling is capped at 100% because producing more than you consume annually does not mean zero grid imports. Neither value represents actual self-consumption, self-sufficiency, or grid independence.
Annual Energy Surplus and Deficit
An annual energy surplus does not equal actual grid export. An annual energy deficit does not equal actual grid import. Determining actual grid flows requires temporal load and production profiles, not just annual totals.
On-Grid vs Hybrid vs Off-Grid Solar
On-Grid Solar Systems
On-grid systems remain connected to the utility grid. The calculator can estimate annual solar energy sizing and preliminary inverter planning. Battery storage is optional in the standard on-grid planning flow. This tool does not provide jurisdiction-specific grid rules.
Hybrid Solar Systems
Hybrid systems combine grid connection with battery storage. Battery storage can shift energy in time and provide backup planning. Battery capacity does not create additional solar generation.
Off-Grid Solar Systems
Off-grid systems require more than annual energy balance. Final sizing requires analysis of seasonality, worst-month solar resource, poor-weather periods, battery autonomy, peak loads, surge loads, battery discharge capability, backup or generator strategy, and system redundancy. The annual result does not prove off-grid adequacy.
Important Solar Sizing Factors
The current calculator uses annual specific yield (kWh/kWp/year) from a manual planning input. Country, region, or city selection does not automatically generate the solar resource value. The system does not automatically retrieve irradiance data from PVGIS, PVWatts, Google Solar, or any other external solar API.
Frequently Asked Questions
Professional Verification Required
Final design should be verified by qualified professionals. This tool does not perform structural, electrical, or grid-interconnection calculations.
Roof and site suitability, structural assessment, local permits, utility and interconnection, electrical protection, wiring, grounding, panel string design, MPPT compatibility, inverter compatibility, and battery compatibility where applicable.