Solar panels in Thunder Bay, ON

Roofs in Thunder Bay get about 1,397 hours of usable sunlight a year — less than 70% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.

Check your specific roof in Thunder Bay → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.

What a typical Thunder Bay solar system costs

A 23-panel system (9.2 kW) is about right for an average Thunder Bay home using 10,800 kWh a year. It would produce roughly 10,925 kWh annually and offset 100% of that usage.

How we worked this out for Thunder Bay

Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from Thunder Bay rooftops.

Step 6 matters more than it looks. Only 35% of what a system this size produces in Thunder Bay is used the moment it is generated; the other 7,145 kWh is exported and credited one-for-one under net metering. Because exports here are credited at or near retail, that split changes the payback very little — 15.8 years against the 15.9 we show. In places where exports pay a fraction of retail the same split moves payback by years, which is why we model it explicitly rather than assuming.

Assumptions: 400W panels, 15% system losses (inverter, wiring, heat, soiling), CA$2.85/W installed, 10,800 kWh typical annual household use, 15.2¢/kWh electricity. Change any of those and every figure above moves — which is exactly why a single national "solar costs X" number is misleading.

Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.

Why Thunder Bay gets 1,397 sun hours

That figure comes from Google's analysis of real rooftops across Thunder Bay — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Thunder Bay reaches about 1,545 hours, roughly 11% better than typical.

The numbers behind this page

When Thunder Bay actually produces

Annual totals hide the thing that catches people out: 40% of Thunder Bay's yearly sunlight arrives in May–July, and just 10% across November–January.

That is a severe seasonal swing — Thunder Bay produces roughly 4.8× as much in Jun as in Dec. A system sized to cover your annual usage will overproduce badly in summer and fall well short in winter, so how your utility credits exported power matters more here than in most places.

The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at Thunder Bay's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.

How Thunder Bay compares to the other 788 cities

What actually stands out about Thunder Bay:

• Shading is a real problem here. Thunder Bay loses 10% of its potential sunlight to trees, chimneys and neighbouring buildings — the 86th-worst of the 788 cities measured. Panel placement matters more here than in most places, and a roof survey is worth more than a phone quote.
• Roof space is the binding constraint. A typical Thunder Bay roof fits about 33 panels and a typical home needs 23 — so there is little room to oversize. If you add an EV or heat pump later, plan the array for it now.
• The case here is financial, not environmental. Thunder Bay's grid is already clean at 151 kg CO₂ per MWh, so the carbon saving from solar is modest. Judge this one on payback.
• Older imagery. Google's aerial capture of Thunder Bay dates from 2016. Tree growth and new construction since then are not reflected.

Cities with almost the same sunlight

These are the closest matches to Thunder Bay's 1,397 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.

Nearby cities

See all of Ontario → statewide sunlight, rates, incentives and every city we've measured.

Thunder Bay solar questions

Worth reading before you buy

Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Ontario electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.