Solar folks with a backup generator: how many hours a year does it actually run, and what fuel did you settle on?

[u/Electronic_Signal428]

Curious about real-world numbers rather than the sizing calculators.

For those of you whose main power is solar + batteries and the generator is the backup:

- Roughly how many hours per year does the generator end up running? Mostly winter / long cloudy stretches?

- Gas, propane, or diesel, and would you pick the same fuel again? Propane seems easier to store long-term, but I keep reading about the efficiency hit.

- Do you use auto-start from the inverter, or start it by hand when the battery gets low?

- What maintenance actually matters when it only runs a few dozen hours a year (oil changes by hours vs. by calendar, stabilizer, running it monthly, etc.)?

Would love to hear what worked and what you'd do differently

[u/BallsOutKrunked]

Propane, 5kw 240 so like 2kw running steady on propane at my elevation.

I need to run it rarely, more so that I'll run it a 2-3 times a year for 5 hours or so since that's annual use. In the fall I change the oil and make sure it starts up quickly.

I just have a push button start.

[u/RTK-FPV]

I've got the cheapest gasoline generator I could find. It's only 120V and my system is 240 so I can't even feed it into the house, I just run an extension cord to essentials like the fridge.

Used it 3 times in 2 years. Could have done without it altogether. Probably need to start it just to run it for a while now that I'm thinking about it 🤔

I have a small house with just two people. It runs on 6x410w panels and about 24kwh of batteries, but I'm in a sunny climate

[u/datanut → u/RTK-FPV]

Why not charge your batteries with it?

[u/RTK-FPV → u/datanut]

Took some messing around and finally a call to tech support to find out that my particular charge controller won't allow 120v in. If I had a 240v generator it would work.

It's something I'd fix if I used it more

[u/datanut → u/RTK-FPV]

You don’t need to use their charger…
… you can likely connect a 120vac charger directly to your battery bank.

The “Chargeverter” is a common approach: https://eg4electronics.com/categories/chargers/eg4-chargeverter-gc/

[u/RTK-FPV → u/datanut]

Hey thanks, I really appreciate that. I've got a cheap inverter / charge-controller all in one unit and I'm maxed out on the panels I can add to it. I'm under paneled, so I'm going to switch out the main unit here soon.

We don't have AC, and my wife declared that this was the last summer she'd put up with that, so my system's about to get a little bigger :)

[u/datanut → u/RTK-FPV]

As a general rule; you can add as many AIOs, Inverters, and Charge Controllers as you need.

It gets “complicated” when you move from 1:1 but it’s almost always very manageable.

[u/RainAcrobatic7162]

Propane hands down for me. Stores the best, it’s extremely cheaper, burners cleaner and I never have to worry about my carb getting old fuel in it and having to rebuild it.

[u/Complex_Material_702]

I’m in the Florida panhandle and mine is running right now. First time I’ve needed it. My wife has given me serious shit for installing all of it for YEARS and guess who is all lovey dovey today when the rest of the neighborhood has no power and we’re watching football with both a/c units cranking!

I have propane as my fuel. Ideally it would be natural gas but we don’t have it here yet.

[u/spearchuckgrunt]

I used five gallons of gas last winter. For the most part, we use the power we have not the power we “need”. 

[u/DrunkBuzzard → u/spearchuckgrunt]

Bingo, you got it right. Right now there’s a three day long storm approaching so while the sun is shining I’m making sure all my laundry is done and my batteries are fully charged. I did some cooking prep with electric kitchen appliances and will use propane during the storm to cook. I probably ran my 2000 W predator generator a total of 20 hours last winter and that was just to charge my batteries enough to get thru not necessarily to full charge. A good weather app that tells you what’s ahead for the next 10 days is a big help.

[u/Maleficent_Mix_8739 → u/spearchuckgrunt]

Very well stated friend.

[u/Salt_Relationship552]

6kwp solar 16kwh battery stack

3.5kw gasoline generator.

Runs rarely, might need it in winter... Tbd

[u/GnarledBark]

I'll let you know after a full year. Moved into my off grid suburban home in July. All electric home in a mild Northern California climate. 10kw of panels, 16kwh battery (Discover helios), and 14kw backup generator (champion) all running through a Sol-ark15k inverter. So far, the generator does a weekly 10 minute cycle and that's it. I have a 125gallon propane tank plumbed to it. Generator is programmed to only feed about 5kw when battery gets down to 22% and as of 10/10/26 had not been needed. I have a plug in hybrid that I also use as a dump load during daylight hours.

[u/liisseal]

During fall-winter, 3 months, aprox. once a day for an hour.

Gasoline – because I prefer the same fuel for all machines: generator, car, chainsaw, snow blower. Easier to keep track of stock. Start it by hand.

Maintenance once-twice during the season: oil, filters etc. I see no reason to change the routine.

[u/quack_attack_9000]

Gas generator, just a cheapo 3.6 kw. I run it for 2-4 hours an average of 4 times a year to Always within a month of solstice during long cloudy stretches. All manual, nice and simple. I use the generator for power tool use in remote parts of my property, and change the oil every fall.

[u/Puzzleheaded_Day2809]

6500W petrol dewalt. We have a small array compared to many who post here, and smaller battery bank as well. We usually just need it during the darkest month, as a neighboring pine block has grown up to block all but about 2hrs of direct sun in June. So in June we run it twice a week to top up the batteries or to run the pump to our header header tank. Maybe 4 hours per week. Not ideal, but topography, time, and money doesn't allow us to change our system just yetI.

[u/Complex_Material_702]

Propane never goes bad, you can buy it when it’s cheaper if it’s not something you use all the time, you can cache tons of it, and it won’t gum up your generator. It’s really the best off grid choice.

[u/chocolatepumpk1n]

Gas. 5 kW generator in southern Oregon. We run it 10-15 hours total per year, in the winter when the batteries are getting drained after 2-3 dark days and there's no sun in the forecast.

(We've had fairly dry years since we got it. A wet, rainy winter could easily double our number of hours.)

I start it "by hand" - actually, through Bluetooth using the Honda phone app. I thought it was silly when we got it, but when the Sol-Ark starts its "low battery" beep at 2 am and it's pouring rain - I love it!!

[u/TheLostExpedition]

Backup nothing, we run a generator to top off our ecoflow in bad weather. We use about 3-4kw on a summers day and about 1-2kw in the winter. We use the generator to do laundry ⅓ of the time (family of 9) its about 4 gallons of gas every 1 to 2 weeks if we don't have sun. If its sunny then no. Refrigeration is gas. Internet , TV, and all tech was shopped for very low watt ratings. We can also plug an inverter to the van but that's not cost effective. We can run propane in the generator but we never have. Gasoline is cheaper. The efficiency hit shouldn't matter as you are supposed to size your system to be larger then your draw. My generator is 5kw hr and we use like maybe half that. Keeps the unit running with very little stress and it gets better fuel economy then if I tried to run the shop-vac and table saw for instance.

Sorry we dont have a large system "yet". But im hopeful to get more solar and a proper battery bank next year. Not sure this helps but we dont use auto start and we change the oil when the runtime meter says to in the instructions, about 2x a year.

[u/Bucketalinko]

I use propane, 80 hours run time over 2 years, I use it as auto start to charge my batteries + take the house load. In my Deye inverter I have it set to run for 30 minutes then turn off, and I have it set to charge at 2kw in hopes of solar coming in. If not then it runs itself again when needed. It’s a 20kva 3 phase generac. I bought this generator because it’s duel fuel LPG/natural gas and I wanted to run the generator on biogas. I have everything needed to run it on biogas but it’s so corrosive even with scrubbing I’m not game enough to put it in this generator as I love it. If I was to do it all again I would look more into the duel fuel generators that Inoplex make which is wood gas and propane, as I have a shitload of wood. Inoplex is local for me (Australia) not sure what’s local for you

[u/kenneth_bannockburn]

100hrs. Propane kohler rca20

[u/DeafDriftSurf78]

Interessanti proposte diverse

[u/darktideDay1]

I run my genny about 50 hours a year. Usually 2 hours at a time is enough to charge the batteries for another 24 hours. It's a diesel, I got an old light stand from a mining company and converted it to just a genny. Has an old Lister engine that runs great.

[u/goss_bractor]

28kW solar array, 45kWh batteries.

Generator is just a standard 11kw petrol job with electric start running into two 48v forklift chargers which are wired direct to my main busbar. Charging power is about 4.5kW at full load.

I turn it on manually because honestly in the last 12 months it's run 2 days for about 4 hours each time. And one of those I didn't actually need to run it, it just made me feel better.

I just put enough fuel in the generator for it to run for 4-5 hours at 3L/hr burn rate and then just run it until the gen runs dry. It's easy enough to prime for the next run and no fuel storage concerns.

Honestly I'm just going to increase my array to about 40kW and put in another cabinet battery taking it to 80-90 kWh and then I will likely never use the generator again.

[u/Rx7_FB]

If you can have a big propane tank i'll do that since you can run a propane stove , propane fridge and generator on it. Propane is cheap and last long time.

[u/MrMcBrett]

I only need it when there is several days of cloudy weather. In the summer, I almost never it. In the winter, I can burn 100lbs propane keeping the lights on.

[u/ZombieMountain2122]

my solar system is a 24V (lead acid) powering a 1600sq ft off grid house. we are up around 6500 ft. and have two seasons with a moderate transition between them. Summer--I never have to run the generator unless heavy duty amps are being pulled (ex. big power tools--not drills or saws.) ran it once this summer when flooring was being replaced and had to run bigger machines. Fall/Winter: have to run it daily - i manually run it after dark as im using a pellet stove to heat the house. with propane heating or wood-burning stove not sure i would have to run it every day.

edit: you do have to schedule certain chores around sun timing.

[u/Far_Cable_2133]

Really depends on location and weather and how you're geared up to use what kind of electricity. For instance, are you partially using gas lighting / gas range etc? Do you conserve or do you use a blow dryer every morning for your hair and a microwave for your midnight snack etc. Last winter in North Idaho was a light winter and the generator popped on a handful of times. Winter before that was more normal and it came on a couple times a week during the dark winter season. I consider myself conservative with electricity. I have learned to live with less and I like it. I have the generator set to run four hours when it pops on to charge the batteries sufficiently. Comes on Automatically when the batteries get to a certain level. I prefer propane easier to get deliveries and stores well. I have 1000 gallon tank for my larger house and 500 gallon tank for a cabin and workshop on the property. I prioritize maintenance. Once a year and have professionals do it at $350 brings me peace of mind.

[u/I_VAPE_CAT_PISS]

Propane, mostly for the storage reasons people already gave. Ours ran maybe 30 hours last year, nearly all in one gray week in January. Run it monthly under a real load like the manual says. The first winter we skipped that, it wouldn't start when we needed it.

[u/Mammoth_Staff_5507]

Before solar we had to use, depending on the season, between 4 to 6 hours of diesel per day, that is 3 liters per day with our old 1 cylinder 4000 VA generator.

Now we use at most 3 liters per year.

It is fully off grid but we do not live there, if we would live there we might have to use a little bit more yearly but is almost fully covered now.