Solar array and battery sizing context
How This Calculation Works
A solar and battery estimate starts with energy use, not panel count alone. This tool compares an inverter output with a panel busbar and main breaker combination, while related tools estimate daily energy and battery runtime. Array power is affected by roof orientation, shading, temperature, snow, inverter limits, and production losses. Battery autonomy depends on usable kWh, depth of discharge, inverter efficiency, surge loads, and the essential circuits selected. Use results to frame questions for an installer, not to promise a particular annual production or outage duration.
Applicable Code Rules & Standards
Canadian PV and energy-storage installations must follow the current CEC/OESC, equipment listings, interconnection requirements, and the local electrical safety authority. Section 64 and related rules address renewable energy systems, storage, disconnects, wiring methods, labelling, and protection. Ontario projects also require utility and ESA coordination. NEC projects may use Article 690, Article 705, and Article 706, but US assumptions must not be copied into an Ontario design. The busbar result is only one check; conductor ampacity, rapid shutdown or emergency controls, grounding, arc-fault protection, and equipment compatibility also apply.
Common DIY/Installation Errors
- Confusing DC array kW with AC inverter output and usable household energy.
- Applying a 120% busbar shortcut without confirming breaker position, equipment listing, or local approval.
- Ignoring roof structure, wind, snow, shading, fire access, and rapid-shutdown requirements.
- Sizing a battery from total house load instead of identifying essential circuits and motor surge.
- Backfeeding a panel or using a transfer device that is not listed for the system.
Production estimates should be compared with seasonal use rather than a single sunny-day result. Winter snow, short days, smoke, shade, inverter clipping, battery reserve, and utility outages all change the result. Ask for assumptions in writing and keep the equipment data sheets. A safe design is one that can be isolated, inspected, serviced, and explained to the next owner, not merely one that produces an attractive number on a proposal.
Keep the AC and DC sides documented separately. A listed inverter may limit output, but that does not remove the need to size conductors, overcurrent protection, disconnects, labels, and equipment grounding for the actual installation and environment.
When to Hire a Licensed Professional
Use qualified solar and electrical professionals for array design, roof attachments, inverters, batteries, transfer equipment, panel interconnections, and utility approvals. A professional will coordinate structural, electrical, fire, and inspection requirements and test the completed system. Do not open energized PV equipment: solar conductors can remain live in daylight even when the main breaker is off.