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How to select best UPS and Solar to be off-grid 24 hour for 2kw

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Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#21

Post by js2 »

This is a job for a generator such as:

https://www.harborfreight.com/3500-watt-super-quiet-inverter...

$850 US, supplies 3000 watts, runs 11 hours at 25% capacity on 2.6 gallons of gasoline. You'd be at 66% capacity, so fuel consumption will be higher. Bring 20 gallons of fuel?

If you go solar, figure you have 6 hours of usable daylight, you'd need seven rooftop sized panels (330 watts each) to supply 2kw for those 6 hours, so you need battery capacity for the remaining 18 hours, or 36 kWh. That's a sizable battery. You'd need 36 of these:

https://www.jackery.com/products/explorer-1000-portable-powe...

(That's obviously impractical so you'd have to custom build a solution.)

I don't know... I'd go with a generator and gasoline. Much cheaper, more compact, and available off the shelf.

Maybe you can get Rivian to lend you a truck for PR purposes. It has four on-board 120v outlets and a 105-180 kWh battery.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#22

Post by m463 »

lazide wrote: post #7

As some other comments noted, there is a lot of information missing to give you a good answer. Do you need to be off grid 24 hrs out of every 24 hrs? (No grid connection, permanent off grid) Do you need to be off grid UP TO 24 hours, with a grid connection most of the time? Is your grid power cheap? If so, how cheap? It might be worth it only as a weather related backup if it is cheap, or might be worth going full of…

and maybe they will be off-grid just say, this thursday.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#23

Post by ineedasername »

Everyone with outdoor access where they live should consider a dual fuel generator that can run some basic things for at least few hours. Dual fuel give you flexibility because gasoline doesn't actually have a great shelf life but a tank of propane will last longer in storage.

I know not everyone can swing the cost for a somewhat discretionary purchase in the $500 to $1000 range, but checking craigslist on a regular basis can turn them up: contractors often use them on job sites.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#24

Post by ineedasername »

js2 wrote: post #21

This is a job for a generator such as: https://www.harborfreight.com/3500-watt-super-quiet-inverter... $850 US, supplies 3000 watts, runs 11 hours at 25% capacity on 2.6 gallons of gasoline. You'd be at 66% capacity, so fuel consumption will be higher. Bring 20 gallons of fuel? If you go solar, figure you have 6 hours of usable daylight, you'd need seven rooftop sized panels (330 watts each) to supply 2kw for those 6…

I love harbor freight for some types of things, but their quality varies widely: I got a cheap drill press and it was crap, I returned it and the replacement is fine.

So my rule of thumb with them is 1) never buy their products for anything safety related and 2) never rely on their products for something that will be truly critical if it breaks.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#25

Post by lazide »

ClumsyPilot wrote: post #13
sigmaprimus wrote: post #5

2kw draw for 24h is actually quite substantial. Don't forget regardless of how sunny it is in Africa, You will still need to have enough stored power to make it through the night. I'm not saying it is impossible but suspect it will cost more in fuel to transport the batteries and panels than it would to just run a small inverter genset instead. If your device doesn't need to be constantly powered then I would suggest…

A generator will consume roughly a liter of diesel per hour at this load. For a stationary installation, a diesel generator would be a terrible idea.

As with many things - ‘it depends’. You’ll certainly crank up some terrible hour counts running purely off a generator, but for only 2kw continuous you can size a generator that will sip fuel. Depending on local fuel prices, it could take many many years before solar would be even close cost wise.

If only 2kw peak, a common strategy is generator to charge a battery bank, also charge when possible the bank with solar, and run inverters off the batteries (or switchover to the generator when charging the bank). Some people just skip the solar panels. Solar has many problems with unpredictability, and if you need to be sure you’ll have power year round, it isn’t a good idea to rely on it 100% without some other way to charge or supplement it. Dedicated off grid folks always have a generator in my experience, even if it rarely has to get fired up.

Sizing a battery bank to give you enough excess to not worry about a freak 2 weeks of bad weather in winter is extremely expensive and has other issues (like not being able to properly cycle or maintain all the batteries due to lack of peak power)

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#26

Post by orthecreedence »

This thread is an interesting micro allegory for how the move off of fossil fuels will be extremely difficult if all we use are solar and wind power.

Kind of drives the point home about nuclear being the best option. And I know, "ohhh it's so expensive." Ok, so stop letting the markets dictate prices and tax all fossil fuels until gas is $25/gallon. Suddenly nuclear is cheap.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#27

Post by giantg2 »

ineedasername wrote: post #24
js2 wrote: post #21

This is a job for a generator such as: https://www.harborfreight.com/3500-watt-super-quiet-inverter... $850 US, supplies 3000 watts, runs 11 hours at 25% capacity on 2.6 gallons of gasoline. You'd be at 66% capacity, so fuel consumption will be higher. Bring 20 gallons of fuel? If you go solar, figure you have 6 hours of usable daylight, you'd need seven rooftop sized panels (330 watts each) to supply 2kw for those 6…

I love harbor freight for some types of things, but their quality varies widely: I got a cheap drill press and it was crap, I returned it and the replacement is fine. So my rule of thumb with them is 1) never buy their products for anything safety related and 2) never rely on their products for something that will be truly critical if it breaks.

Similar experience here. I would only buy hand tools from them, or buying other stuff with the expectation that it's only going to last for one job. Anything electronic or with a motor doesn't seem to last.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#29

Post by snypher »

js2 wrote: post #21

This is a job for a generator such as: https://www.harborfreight.com/3500-watt-super-quiet-inverter... $850 US, supplies 3000 watts, runs 11 hours at 25% capacity on 2.6 gallons of gasoline. You'd be at 66% capacity, so fuel consumption will be higher. Bring 20 gallons of fuel? If you go solar, figure you have 6 hours of usable daylight, you'd need seven rooftop sized panels (330 watts each) to supply 2kw for those 6…

Please buy a Honda generator and don't waste time with a Harbor Freight (Hazard Fraught) one. You need this to work in a time of peril - not a use case for HF tools.
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