Solar Panel Size Estimator
Enter your energy target and your own system assumptions.
A QUICK WALKTHROUGH
How to use this tool
- Choose a daily or annual target and enter its energy amount.
- Enter your own peak sun hours and efficiency; optionally supply panel watts.
- Add your own sun-hour scenarios if wanted, then calculate and export the report.
Target period
Daily: P = E/(h × η/100); annual: P = G/(365 × h × η/100); Y = 365 × h × η/100
Period and scenario assumptions
A year is exactly 365 modeled days. The same user sun hours and efficiency apply every day. Switching period clears the target field so yesterday’s daily value cannot become an annual value automatically.
Required array size
Zero target produces zero array size and zero panels when a panel rating is supplied; the positive per-kW yield remains defined.
Solar sizing report
Calculated values use approximate JavaScript floating-point arithmetic without fixed decimal rounding. Original inputs and parsed values are kept in the report; panel counts use exact decimal ceiling.
Solar Panel Size Estimator
No geographic sunlight data or site design is supplied. Seasonal variation, shading, battery losses, permitting and electrical-code requirements are outside this arithmetic model.
GOOD TO KNOW
Common questions
Is this an installation design?
No. The outputs depend only on your supplied target and assumptions.
Why round the panel count up?
The optional count uses the smallest whole number whose rated watts meet the calculated capacity under the model.