How big a solar system does an off-grid cottage need?

It depends on your daily use and season. Start with a load list in watt-hours per day, then size the battery for two or three days and the panels to recharge it.

Can I use solar at my cottage in winter?

Yes, but production is much lower in December and January. Most year-round off-grid cottages rely on a generator or a much larger system in winter.

Do I need a permit for off-grid solar at a cottage?

Usually yes. In Ontario, electrical work should be done by a Licensed Electrical Contractor who files an ESA notification, and your township may have its own building or zoning rules.

Can lithium batteries freeze at the cottage?

Most lithium batteries can't be charged below freezing unless they have built-in heating. Follow the manufacturer's storage instructions if the cottage is closed for winter.

Is solar worth it for a grid-connected cottage?

Only if you use enough power. A cottage used a few months a year may not save enough to pay back the system, since fixed charges remain.

Off-grid solar for cottages

Off-grid vs grid-tied cottages, battery sizing basics, seasonal use, generators, snow and freezing temperatures, plus the safety and permit rules.

6 min read · Updated 2026-10-30

Solar is a natural fit for many Canadian cottages, especially ones far from power lines. But an off-grid system works very differently from a grid-tied home system, and it is easy to undersize or overspend. This guide covers the basics so you can have an informed conversation with an installer.

Off-grid vs grid-tied cottages

Grid-tied cottage. If your cottage already has utility power, a grid-tied system works like one on a house. Panels offset what you use, and in places with net metering, summer surplus can earn credits. Watch out for low use, though. A cottage used a few months a year may not use enough power for solar to pay back, since fixed monthly charges stay. See how solar payback works.

Off-grid cottage. If there is no utility connection, or bringing one in would cost a lot, solar with batteries can be your power source. You have to produce and store everything you use. There is no grid to fall back on, so most off-grid cottages also keep a generator.

Start with what you actually use

Off-grid design starts with a load list, not a panel count. Write down what you want to run, its power in watts, and how many hours a day you use it.

Item	Watts	Hours per day	Wh per day
LED lights (8 bulbs)	80	5	400
Efficient fridge	100 average	24	About 1,000 to 1,500
Water pump	500	1	500
Phones, laptop, router	100	4	400

These are illustrative figures. Use your own appliances' labels. The example adds up to roughly 2,300 to 2,800 Wh, or about 2.3 to 2.8 kWh per day.

Big loads change everything. Electric heat, electric water heaters, electric stoves, dryers and air conditioning use far more than a modest solar and battery system can supply. Most off-grid cottages use propane or wood for heat, hot water and cooking.

Battery sizing basics

The battery stores energy for nights and cloudy days.

Daily use. Start with your daily kWh, such as 2.5 kWh.
Days of autonomy. Decide how many cloudy days you want to cover without a generator. Two to three days is common for summer use.
Usable capacity. Batteries should not be drained to zero. Lithium iron phosphate (LFP) batteries can use most of their rated capacity. Lead-acid batteries should usually be discharged only partway to protect their life.

For example, 2.5 kWh per day for 2 days needs about 5 kWh of usable storage. That might be about 5.5 to 6 kWh of rated LFP capacity, or roughly double that in lead-acid.

Your installer will also size the panels to recharge the battery in a reasonable time and the inverter to handle your largest loads starting at once, such as a pump and fridge together.

Seasonal use

How you use the cottage drives the design.

Summer only (May to October). The easiest case. Long days make it simple to produce enough with a modest array. In our Toronto sample system, May to August produce more than half of the year's output.
Three-season use. Spring and fall days are shorter. Plan for more panels, more storage, or more generator time.
Year-round use. The hardest case. In December and January, production can be a fraction of summer. In our Toronto sample, December produces about one-ninth of July. Most year-round off-grid homes rely on a generator in winter, or a much larger system.

Natural Resources Canada's solar maps show monthly solar potential for your area, which helps you plan for the months you will be there.

Generators

A generator covers long cloudy stretches, winter and heavy loads. Many off-grid systems can start a generator automatically when the battery is low.

Safety rules for generators:

Never run a generator indoors, including in a garage, shed or crawl space. Generators produce carbon monoxide, which can reach fatal levels. Open doors and fans don't make it safe.
Place it outdoors, in a dry area, away from doors, windows and vents.
Install carbon monoxide alarms in the cottage.
A generator connected to your cottage wiring needs a proper transfer device so power can't flow back into utility lines. In Ontario, that connection needs an electrical permit, and ESA strongly recommends a Licensed Electrical Contractor.

Snow and freezing temperatures

Battery temperature. Most lithium batteries can't be charged safely below freezing unless they have built-in heating. Check the spec sheet. A cottage closed for winter usually needs the battery stored or kept in a protected space, following the manufacturer's instructions.
Lead-acid batteries can freeze if left discharged in the cold.
Snow. Steeper panel tilts, often on a ground mount, help snow slide off. See solar panels and snow.
Water lines. Off-grid power does not change winterizing. Drain water systems if the cottage is unheated.
Ventilation. Lead-acid batteries can give off hydrogen when charging and need a ventilated space.

Safety and permits

Off-grid doesn't mean outside the electrical code. Solar panels, batteries, inverters and wiring all carry fire and shock risks.

In Ontario, electrical work should be done by a Licensed Electrical Contractor, who files a notification with ESA and has the work inspected. Other provinces have their own electrical permit rules.
Equipment must carry a recognized Canadian certification mark. Cheap imported off-grid kits often lack one.
Your township may have building or zoning rules for ground mounts or battery sheds.
Tell your cottage insurer about the system. See solar and home insurance.

Next step

If your cottage is grid-connected, check your roof to see whether solar pays back. For off-grid, bring your load list to an installer and compare quotes with our quote checker.

Common questions

How big a solar system does an off-grid cottage need?: It depends on your daily use and season. Start with a load list in watt-hours per day, then size the battery for two or three days and the panels to recharge it.
Can I use solar at my cottage in winter?: Yes, but production is much lower in December and January. Most year-round off-grid cottages rely on a generator or a much larger system in winter.
Do I need a permit for off-grid solar at a cottage?: Usually yes. In Ontario, electrical work should be done by a Licensed Electrical Contractor who files an ESA notification, and your township may have its own building or zoning rules.
Can lithium batteries freeze at the cottage?: Most lithium batteries can't be charged below freezing unless they have built-in heating. Follow the manufacturer's storage instructions if the cottage is closed for winter.
Is solar worth it for a grid-connected cottage?: Only if you use enough power. A cottage used a few months a year may not save enough to pay back the system, since fixed charges remain.

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