Solar Panel, Battery & Inverter Calculator
Estimate how many solar panels, how much battery storage and what inverter system you need based on your location and electricity usage.
1. Location
Choose your country (and region if available) to set typical peak sun hours.
Quick start
Pick a goal to pre-fill sensible defaults.
Type of home: pre-fill typical appliance usage.
2. System Settings
Adjust assumptions used in panel and battery sizing.
3. Appliances & Energy Usage
Select appliances and adjust sliders for power draw and usage hours.
Energy Demand Summary
Results are estimates. Real systems should be validated by a professional installer.
4. Inverter Recommendation
Answer a few quick questions. We’ll use your demand and battery results above to suggest a suitable inverter approach.
Learn more
How the calculator works
- Energy use: You enter how long you use each appliance during the day and at night. The tool totals your daily energy demand (kWh).
- Solar panels: It estimates how much energy one panel can produce in your location (panel watts × sun hours × efficiency), then recommends the number of panels to cover your daily demand.
- Battery: It sizes the battery mainly from your night-time demand and the number of backup nights you choose, adjusted for a safe usable fraction (Depth of Discharge).
- Inverter: It uses your peak load estimate plus your solar/battery setup, combined with a few questions about your roof and backup needs, to recommend an inverter approach and power class.
Assumptions: Results are planning estimates. Real-world output depends on roof orientation, shading, temperature, wiring losses, and local grid rules. Always confirm with a certified installer.
Common sizing mistakes
- Overestimating sun: Using a sunny-day assumption instead of your location’s average sun hours.
- Ignoring night usage: Battery size depends mainly on what you run after sunset (and how many backup nights you want).
- Trying to back up everything: Whole-home backup is expensive. “Essentials only” often gives the best value.
- Forgetting big loads: EV charging, heat pumps, and electric cooking can dominate inverter sizing.
- Not accounting for losses: Every system has conversion and wiring losses. Efficiency settings are important.
FAQ
Is this tool accurate?
It’s a planning tool designed to give a realistic starting point. Your installer should confirm final equipment choices, string design, and local grid compliance.
Why does the panel recommendation change when I change location?
Different places receive different average sun hours per day. Fewer sun hours means you need more panels to produce the same daily energy.
What’s the difference between kW and kWh?
kW is power (how fast you use energy). kWh is energy (how much you used over time). Batteries are sized in kWh. Inverters are sized in kW.
Do I need a battery?
Not necessarily. Batteries increase own-consumption and provide backup, but they add cost. If you only want bill savings, a grid-tied solar setup can work well without a battery.
How do I choose “backup nights”?
Think about how long you want essentials to run without the grid. One night is common. Two nights adds resilience, but increases battery size.
Why does the inverter recommendation change when I change inputs?
The inverter must handle peak power (kW) and, in some modes, the solar array size. If you add big loads or increase backup scope, a larger inverter may be recommended.
What does “Essentials only” backup mean?
It means you choose a smaller set of circuits (fridge, lights, Wi‑Fi, etc.) for backup. This usually reduces inverter and battery requirements and lowers cost.
What’s the “peak load estimate” used for?
It’s a practical estimate of how much power you may use at one time, adjusted so it doesn’t assume every device runs simultaneously. It helps size the inverter.
Should I include EV charging in my backup plan?
Usually not. EV charging is a large load and can dramatically increase inverter and battery requirements. Most people keep EV charging on grid-only.
How do shading and multiple roof directions affect the inverter?
Shading and mixed roof directions can reduce solar output. In these cases, optimizers or microinverters may improve performance and monitoring.
Can I use this tool to compare scenarios?
Yes: Adjust your appliance hours and backup choice to compare “bill savings only” vs “backup essentials” vs “whole-home backup.” Use “Save & Share” to keep and share scenarios.
Does this include local permits and grid export limits?
No. Grid rules vary by country and network operator. Use the results as a starting point and confirm compliance with your installer.
Glossary
- Peak sun hours
- An average daily measure of usable sunlight. More peak sun hours means panels produce more energy per day.
- Depth of Discharge (DoD)
- The usable fraction of a battery. Using a battery less deeply can extend its life.
- Round-trip efficiency
- The percentage of energy you get back after charging and discharging a battery. Some energy is lost as heat.
- kW vs kWh
- kW is power (Rate of energy use). kWh is energy (power discharged or drawn for a duration of time). Inverters are rated in kW. Batteries are sized in kWh.