The calculator converts annual electricity usage into required solar generation, then translates that demand into DC system size, panel count, and estimated roof area. It applies performance assumptions for real-world losses and shading so early planning decisions are less likely to undersize the system.

Practical Sizing Tips

Start with accurate annual consumption and avoid over-relying on a single month bill. Use moderate assumptions for site losses and validate final output with installer production models. If you are planning for EV charging or electric heating, include projected load growth in your offset target.

• Use 12-month utility history for reliable load baseline
• Adjust offset target for tariff structure and export credit rules
• Check usable roof area after setbacks and obstructions
• Model shading conservatively to avoid undersizing risk
• Compare sizing output with a solar ROI model before purchase
• Revisit system design if future electrification is planned

Sources & References