Path-Q Solar

How should I size solar for a rental home when electricity use varies substantially between tenants?

Answer

Size the system from a documented range of likely electricity use rather than from one tenant's bill. Use multiple years of bills when available, separate owner-controlled loads from tenant loads, and compare conservative, typical, and high-use scenarios. A system sized for unusually high consumption may produce excess energy when occupancy or usage changes.

Key points

  • Tenant behavior, occupancy, heating and cooling use, and appliance ownership can materially change consumption.
  • The system should reflect the landlord's financial objective, such as reducing common-area costs, supporting included utilities, or improving property appeal.
  • If the tenant pays the electricity bill, the landlord may receive limited direct value from a larger system unless the arrangement provides another benefit.
  • Designing for future electrification can be reasonable, but it should be based on planned equipment rather than speculative usage.

What it depends on

  • Historical bills and their coverage of occupancy periods
  • Whether utilities are paid by the landlord or tenant
  • Occupancy, heating, cooling, and appliance patterns
  • Roof capacity and the property's expected holding period

Risks and trade-offs

  • Oversizing can increase upfront cost and leave more energy exported or unused.
  • Undersizing may miss future loads such as heat pumps, electric water heating, or vehicle charging.
  • Tenant turnover makes consumption estimates uncertain even when the building itself is unchanged.

Information you may need

  • At least 12 months of electricity bills, preferably across multiple tenants
  • Occupancy and utility-payment arrangements
  • Existing and planned electric equipment
  • Roof layout and any expected property changes

Your next step

What to do next

Create low, typical, and high annual-use scenarios from the available bills and ask for system designs showing production and economics under each scenario.

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