Solar Economics

We look at a potential solar panel installation on my house, to see mathematically at least what a solar setup would look like on my roof. We find that we can satisfy about a third of my overall energy needs just from the roof. As I live in Toronto Ontario, where the energy mix is fairly low-carbon, the climate benefits would be minimal. Further, electricity is quite cheap, hence the economics are also iffy. A Portable battery/solar generator might provide me with the reliability benefit a solar system provides at a much reduced cost, allowing me to keep going in the case of a blackout.

My roof measures a little over 12 meters long, and the south-facing side is about 2.7 m tall. This might conceivably allow for the installation of 12 solar panels (these are usually about 2 x 1 m source), each generating ideally 400W, for a peak generating capacity of 4.8 kW which might produce about 4.8 MWh per year (source). Looking at my carbon audit, seems we consume about 7.2 MWh on an annual basis (see this post), this might double if I switched my heating from natural gas to electric. Thus total “house-usage” might be about 15 MWh of electricity, of which my solar project might generate a third. This accounts for about 6% of my household emissions.

So, I could not generate enough energy here to offset our entire usage for the year, does the project make financial sense? Approximate installation costs can be had from our estimate of 4.8 kW generating capacity. Energyhub estimates installation costs at about $3.01 per W, which adds up to about $16 000. Each kWh generated might save perhaps 16 cents off my energy bill, thus my annual production of 4.8 MWh saves about $768 in energy costs. Even assuming zero interest, it would take a whopping 20 years for that to add up to the $16 000 installation costs. Apparently there is a federal $5000 incentive available, which makes the payback period 14 years (source). Financially anyways, its at best a break even proposition. A repair bill say from a fallen tree or hungry squirrels (apparently squirrels like wiring) could easily set the payback period back much further.

Granted, I am fortunate enough to live in Toronto, Ontario, where the grid is apparently fairly green (source). That may not be the case where you live. For example, some communities in Canada’s North fly in Diesel to power generators, a polluting and expensive proposition (source). There a solar project makes a ton of sense. Please leave a comment if you know of a way I can contribute, as putting a solar system on a roof in a community relying on fly-in Diesel for power gives us all a way greener planet than putting a solar system on my roof.

So, for me, the solar panel project is an expensive way offset only 6% of my emissions. However, there is some benefit in the resiliency. A solar-battery system, could keep things going in a blackout. For that application, there is no need to spend $16 000. In fact both ecoflow, or bluetti both have solar-battery systems that are powerful enough to charge your car. Plus these can be brought along on a road trip for a little extra range.