Community & shared solar
Allocate a shared roof system's cost and output by each unit's percentage of common interest, the same figure your declaration already uses for voting and expenses.
Percentages don't need to add up to exactly 100. The tool normalizes them automatically based on the units you enter.
How it works
Step 1
This figure is already defined in your condo declaration, typically in an exhibit or schedule listing every unit. It's the same percentage used for voting rights and common expense assessments.
Step 2
An installer quote and production estimate for the full building's roof gives more accurate numbers than a rough guess. The solar panel calculator can help size the system to the building's needs.
Step 3
Most declarations require a supermajority for capital improvements to common elements. Check the HOA feasibility tool for governance considerations that apply similarly to condo associations.
Condo declarations already assign each unit a fixed percentage of common interest that governs voting power and common expense obligations. Applying this same percentage to solar system cost and output avoids creating a separate allocation formula and keeps the arrangement consistent with how the building already handles shared responsibilities. The DSIRE database keeps the current program details, and it is worth a look before you decide.
A condo building's roof area often can't generate enough output to offset every unit's full usage, especially in taller buildings with more units than roof space. In this case, the allocated output simply represents each unit's proportional share of whatever the roof can produce, which may only offset a partial percentage of any individual unit's actual usage. Compare against the multi family cost split calculator if a usage-based split fits your situation better. The roof space versus output estimator can confirm exactly how much your specific roof can support before you commit to an allocation method.
The mechanism for crediting each unit depends on metering setup. If units are separately metered and the utility supports it, individual credits may flow directly to each owner's bill. If not, the association may need to collect and redistribute value through common expense adjustments instead. Confirm which applies with your utility and installer before finalizing plans, and check the multi tenant building allocation tool for how similar buildings have handled this. The Department of Energy's community solar basics guide covers the same crediting mechanism from the offsite-subscription angle, useful context even for an on-building installation.
If installing on the building's own roof proves complicated or the roof can't support meaningful output, individual owners could instead subscribe separately to an offsite community solar array. This sidesteps roof capacity limits and the shared installation process entirely. See the ownership vs subscription comparison tool for how the two paths compare financially. A similar building-versus-offsite tradeoff comes up for larger properties too, covered by the multi-building portfolio solar sizing tool. Check the DSIRE database for your state's rules on shared building installations, since a handful of states have specific provisions for condo and multi-unit solar arrays.
Questions
Most condo declarations already assign each unit a percentage of common interest, used for voting rights and common expense allocation, and this same percentage is typically applied to shared solar system costs and output. A unit with a 10% ownership share pays 10% of the system cost and receives 10% of the output.
Ownership percentage is already a legally defined figure in the condo declaration, making it simple to apply consistently without needing individual usage data or ongoing metering adjustments. Some associations do choose usage-based splits instead, but this requires separately metered units and more administrative tracking.
Most condo declarations require a supermajority vote for capital improvements to common elements, and roof-mounted solar typically falls into this category. Check your specific declaration for the exact voting threshold, since it varies by association and sometimes by improvement type.
The solar allocation stays tied to the unit itself, not the individual owner, so it automatically transfers to the new owner along with the unit's ownership percentage. This works the same way common expense obligations transfer with a condo sale.