How to use this calculator
- Enter your monthly electricity bill and the rate per kWh printed on it.
- Choose how much of your use you want solar to cover.
- Check the sun hours, efficiency, panel size and roof space per panel.
- Read the suggested kW size, the number of panels and the roof area.
- Take the numbers to installers and compare their quotes.
Sizing a home solar system the simple way
A system that is too small barely dents your bill, while one that is too big costs more than it saves. Sizing starts with how much electricity you really use, which your bill already tells you.
This calculator converts your bill into kWh, then into the kW of panels needed and the number of panels that fit your choice. The roof space result tells you early if the plan can fit your roof.
Next, test the savings with the solar payback calculator, plan for outages with the battery backup calculator, and read the solar power cost guide.
How the system size is worked out
- Your monthly use in kWh is your bill divided by your rate per kWh.
- The energy to cover per day is that use times the share you choose, divided by 30.
- Each kW of panels makes about the sun hours times the efficiency in kWh per day, so the size needed is the daily energy divided by that number.
- The panel count rounds up to whole panels, and roof space and cost follow from it.
Tips to save more
- Cut waste first. A smaller bill needs a smaller system.
- Share your roof photos and bills with installers to get accurate quotes.
- Ask about shading, roof strength and warranty.
- Compare at least three quotes with the same system size.
Frequently asked questions
How many solar panels do I need for my house in the Philippines?
It depends on your electricity use. A home using about 500 kWh a month often needs roughly 3 to 4 kW, which is about 6 to 8 panels of 550 watts. Enter your bill to see your own number.
How much roof space do solar panels need?
A 550 W panel is roughly 2.3 to 2.7 square meters, plus clear space around the array for access and spacing. The calculator uses the panel area you enter.
Should I cover 100 percent of my bill?
Not always. You use the most power at night, so a smaller system that covers daytime use can have a faster payback. Compare sizes with the payback calculator.
What are full sun hours?
They are the hours per day with strong sunshine. Around 4 to 5 is a common planning figure in the Philippines, and it varies with location and season.
Are the prices real quotes?
No, they are example values. Get several written quotes that list the panel brand, inverter and warranty.
Helpful guides and deals
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Solar Panel Payback Calculator Philippines Estimated savings and payback period for home solar Solar Battery Backup Calculator Battery size and inverter for brownouts and blackouts Electricity Bill Calculator Appliance cost per month and your biggest power hogs
This calculator gives estimates for planning only. It is not financial, tax or legal advice. Confirm exact figures with your employer, bank, lender or the relevant government agency.