Community & shared solar
Split a shared solar array's cost and credits fairly across up to 4 units, based on each unit's actual electricity usage.
How it works
Step 1
Pull 12 months of usage from each unit's utility account if they're separately metered. If the building has a single shared meter, you'll need to estimate a reasonable split instead, or consider a separate multi tenant allocation approach.
Step 2
Get an actual installer quote for system cost rather than a rough guess. The solar panel calculator can help size the system to the building's combined usage first.
Step 3
Whatever split method co-owners agree on, document it clearly before installation to avoid disputes later, especially if one unit's usage changes over time.
Splitting cost and credits by usage share ties each unit's financial contribution directly to how much benefit they receive from the system. A unit using 42% of the building's total electricity pays 42% of the cost and gets 42% of the credits, which most co-owners find intuitively fair compared to an equal split regardless of usage.
Buildings with a single shared meter for all units need an alternative basis for splitting, since individual usage data isn't available. Square footage, number of occupants, or a simple equal split among units are common substitutes, though each has tradeoffs worth discussing openly with co-owners. See the neighborhood co-op cost split tool for another approach to shared ownership arrangements. Check the DSIRE database for any state rules on shared-meter solar billing, since this varies by jurisdiction.
A small multi-family building, like a duplex or triplex with a small number of owners, usually involves a simpler informal agreement between co-owners. A condo association or HOA typically requires more formal governance, since decisions affect a larger group and often involve association bylaws. Check the HOA feasibility tool if your building falls into that category instead. A larger residential portfolio faces a similar structural question at greater scale, covered by the multi-building portfolio solar sizing tool.
If installing a shared system on the building itself is complicated by ownership structure or roof condition, each unit could instead subscribe separately to an offsite community solar array. This avoids the joint ownership and maintenance questions entirely, since each unit's subscription is independent. Compare this option with the multi tenant building allocation tool. The Department of Energy's community solar basics guide covers exactly this offsite subscription structure in more depth if it's worth exploring further.
Questions
Most owners split costs proportionally by each unit's electricity usage, so a unit using 40% of the building's total electricity pays 40% of the system cost and receives 40% of the credits. This ties each unit's contribution to their actual benefit.
Usage-based splits are more common and generally fairer, since square footage doesn't account for how efficiently a unit is occupied or how much electricity it actually draws. A smaller unit with a lot of electronics could use more power than a larger, sparsely used unit.
Most cost-sharing agreements set the split once at installation based on historical usage, rather than adjusting it dynamically. If usage patterns shift a lot over time, co-owners can agree to revisit the split, though this requires everyone's consent to change.
This depends on the setup. A system installed directly on a multi-family building is typically owned jointly and its output split by agreement, while a community solar subscription instead lets each unit hold a separate subscription share to an offsite array.