September 16, 2025 · by Larry Dahl
The short version: before the snow flies, top up and check your batteries, tighten every connection, confirm your charge controller's temperature sensor is working, steepen your panel tilt for the low winter sun, and — most important — test your generator under load while it's still nice out. Twenty minutes now saves a cold, dark surprise in January.
Every September I get the same nervous calls. Someone had a great summer running their off-grid place, the sun did all the work, and now they're wondering what they need to do before winter shows up. Good news: it's not much. But the little bit you do in the fall is the difference between a quiet winter and a 2 a.m. scramble with a flashlight. Here's my checklist after 25 years of doing it on our own place.
1. Look after the batteries first
Winter is hard on batteries, and they're the heart of an off-grid system. Get them fully charged now — a battery that goes into winter already down never really catches up once the sun gets weak. If you're on flooded lead-acid, check and top up the water. If you're on lead-carbon or sealed batteries, just confirm they're charging up to full.
And check that temperature sensor on your charge controller. Cold batteries need a higher charge voltage than warm ones, and that little sensor is what tells the controller to bump it up. I've seen whole banks limp through winter half-charged because a sensor wire came loose in the spring and nobody noticed.
2. Tighten every connection
Heat and cold make metal expand and contract, and over a season that works connections loose. A loose connection is a hot connection, and a hot connection is where trouble starts. Go through your battery terminals, your DC disconnects, and your combiner box with a wrench and snug everything up. Five minutes, and it heads off the most common failure I see.
3. Set the panels up for winter sun
The winter sun sits low, so steepen your panel tilt if you can — it points the panels right at it and helps snow slide off instead of piling up. If you're not sure what angle to use, our guide on panel angle and direction in Canada lays it out by region. Give the glass a look too, but don't go climbing an icy roof for a couple percent.
4. Test the generator like you mean it
This is the one people skip, and it's the one that bites. Your backup generator is your insurance for the dark stretch in December when the sun barely shows. Start it now, put it under real load, and make sure it actually carries your system and charges the bank. Change the oil, check the fuel, confirm it starts easy. A generator that's sat since spring is exactly the one that won't fire when you need it at forty below.
5. Know your worst-month math
Fall is a good time to be honest about whether your system is actually sized for winter, or whether you got by all summer on easy sunshine. If you found yourself running the generator more than you'd like, it might be a battery or panel shortfall, not just weather. Our battery bank sizing guide walks through the numbers, and if you'd rather have us look at it, that's what we're here for.
Frequently asked questions
When should I do fall maintenance on my solar system?
Late September into October, before the first hard freeze and before the snow flies. You want your batteries topped up, your connections tight, and your generator tested while it's still comfortable to be outside working on it.
Do I need to clean my solar panels before winter?
Give them a look, not necessarily a scrub. A summer's worth of dust and pollen knocks a few percent off. A quick rinse on a mild day helps, but don't climb an icy roof to do it — the risk isn't worth the couple percent.
Should I change my charge controller settings for winter?
If you run flooded or lead-carbon batteries, cold temperatures change the ideal charge voltage. Many charge controllers have a temperature sensor for exactly this. Make sure it's connected and reading, or your batteries will be chronically under-charged all winter.
How often should I run my backup generator?
Start it now, under load, and confirm it actually carries your system and charges the bank. Then run it monthly through winter even if you don't need it — a generator that sits all fall is the one that won't start at minus thirty when you finally do.
Not sure what your site can handle?
Every property is different — trees, roof pitch, how much of the year you're actually out there. Send us the details and we'll help you get it right. No pressure, no hard sell.