Monocrystalline vs polycrystalline solar panels in Canada

What is a monocrystalline solar panel?

Monocrystalline panels use cells sliced from a silicon ingot grown as one continuous crystal. The orderly structure lets electrons move with less resistance, so the cells are more efficient. Monocrystalline panels look uniformly dark, often black, with rounded or trimmed corners on older designs and full rectangles on newer ones.

Polycrystalline panels use cells cast from many smaller silicon crystals melted together. They show a speckled blue surface and traditionally cost less to make, but give slightly lower efficiency. Thin-film panels are a third group, used mainly on large flat roofs and special applications. The basic rating idea is explained in solar panel efficiency in Canada.

What are the advantages of monocrystalline panels?

The main gain is power per square metre. For a given roof, higher-efficiency panels let you install a larger system, which helps where space is tight or the roof is broken up by vents and dormers. Typical residential panels in this class sit in the high teens to the low twenties for percent efficiency, with figures changing as the technology improves.

Other benefits follow. Their temperature coefficient is often better than older panel types, meaning they lose less output as cells warm, which helps on hot summer roofs. They tend to carry long warranties and degrade slowly, a topic covered in solar panel lifespan and degradation. Cold, bright Canadian winter days suit them well, though low sun and snow still limit output, as discussed in solar panels in winter.

What are the drawbacks?

Historically they cost more per watt, and some still do, though the market now sells mostly monocrystalline cells, so the price gap has narrowed in many places. Manufacturing wastes some silicon, which affects cost and embodied energy. A higher price tag also means the panel's premium has to be justified by the extra output you can actually use.

Do not pay for efficiency you cannot use. If your roof has plenty of space, a lower-rated panel at a lower price per watt can deliver the same yearly energy for less. The price per watt explanation shows how to compare. Remember that one very efficient panel on a shaded roof is still shaded.

What technology terms will you see on a data sheet?

Spec sheets include terms such as PERC, n-type, half-cut cells, bifacial and TOPCon. They describe cell architecture and construction. Half-cut cells reduce losses and cope better with partial shade. Bifacial panels collect light on both faces and can add a little output over bright ground or snow. N-type designs generally promise slower degradation and better behaviour in heat. None of these terms guarantees a better outcome for your house, so compare the numbers that follow them.

• Efficiency and power rating. Watts per panel and per square metre.
• Temperature coefficient. How much output drops as cells heat up.
• Degradation guarantee. How much output the maker promises after a set number of years.
• Product warranty. Coverage for defects, explained in solar panel warranties.

How do you choose between panel types?

Start with the roof and your energy use, not the cell type. Work out how much space you have, how much power you want and what the quotes say per watt. Then compare the data sheets for the models offered, since the same panel type varies a lot between products. Use how to compare solar panel quotes to line them up, and solar panel cost in Canada for the cost drivers.

Panels that make electricity are a different product from heat-collecting panels. For the comparison, see solar thermal versus solar PV.

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