Shared Solar Heat or a Roof of Your Own

What do the two terms mean?

Rooftop solar normally means photovoltaic panels that generate electricity for one house, with the surplus sent to the grid. Community solar heating uses solar thermal collectors, which make heat rather than electricity, and shares them across a group of buildings through a loop of pipes and usually a store. The comparison is therefore between two kinds of energy and two ownership models. The technology contrast is explored in solar thermal versus solar PV.

Where does the shared model help?

A group can build one large store and one control room instead of fifty small ones. Larger stores lose a smaller share of their heat, as described in seasonal thermal energy storage. Collectors can be placed where roof angle and shading are best, not where each house happens to sit. Professionals run the system, and no single owner has to learn about glycol, valves or sensors.

Drake Landing used this approach: 800 flat-plate collectors on garage roofs, 144 boreholes under a park, and a district loop to 52 homes. See solar collection for the collector layout.

Where does rooftop solar win?

It is simpler. One owner decides, one contractor installs it, and the panels connect to the home's wiring and the grid. There are no shared pipes, and the product is electricity, which can power a heat pump, a car or the whole house. Rooftop electricity also has clear rules in many provinces for connection and credits; see Alberta net metering for one case. A shared heating system depends on neighbours agreeing and on someone owning the plant.

How do cost and output compare?

No fair single figure exists, because the products differ. A shared system's cost rests on pipes, storage and a plant that took years of design. A rooftop system's cost rests on panels, inverter and labour; see solar panel cost in Canada. The sensible comparison is cost per useful unit of heat delivered, over the full life of the system, including operation and replacement. Request quotes that spell out those items.

What does Drake Landing say about this?

Drake Landing's monitoring reported a 97% solar share of space heating by 2012 and 100% in the 2015-16 heating season, a share rooftop panels alone would not reach for heat, since there is no seasonal storage. It also shows the risk of a shared model: the system was wound down from around 2020 and decommissioning began in 2024. A rooftop array can keep working when a neighbour does not. For more on the project, see the overview.

Which should a community consider first?

Begin with the building. If homes are efficient, close together and designed for low-temperature heat, a shared thermal system has a chance. If they are older, spread out or on individual lots with different owners, rooftop panels combined with heat pumps are simpler to deliver. Ownership matters as much as engineering: a shared system needs a body that will operate it, bill for it and replace parts for decades. If no such body exists, the technical case does not matter.

A middle path also exists. A community can pursue shared solar power arrays, or use rooftop solar to feed individual heat pumps, which keeps ownership simple while still cutting fuel use. The right pick depends on local electricity prices, roof conditions and winter demand, so compare quotes rather than slogans.

One practical test is the winter month. Ask any installer or system designer what share of December heat their design supplies, and how. A vague answer is a warning sign for either option.

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