Using battery banks helps quite a bit, as you can use a larger, more efficient generator to charge the banks quickly and can size it perfectly to do so, then shut it off. So you might only be running the generator for 4-5 hrs a day or less. This helps with wear and tear, lets you be more efficient, etc. How efficient you can get depends a lot on the specific battery chemistry (columb efficiency), bank voltage, max charge rate (C rate, which is very high for lithium, less high for lead/acid), etc. so hard to calculate here.

I personally use a small inverter generator to power ~ 2kw (1.8 specifically) loads for long periods of time off grid. I don't bother with a battery pack in this case, though eventually I will. I also use propane (since I can store/refill a 1000 gallon tank with no worries about it going bad - it will be fine for a decade or more, it's easy to transfer to portable bbq size containers, etc), and propane is $2.4/gal where I'm at in bulk.

It supports that 1.8~kw/h load continuously, and burns ~ a 5 gallon propane tanks worth in 10 hours at that load. Lower loads, it will go as long as 18. This is at altitude (4500 ft), no supercharging or anything, so you'd get ~ 30% more efficiency at sea level. That is roughly half a gallon of propane for 1.8kw/h, or about $1.50/kwh - pretty much the most expensive and inefficient way to generate power using a generator I imagine. Diesel generators are far more efficient for the power they produce, but generally also output much more power and idle burns more fuel, but fuel is less stable - important for me in this case, not if you're running it a lot. If I was using diesel, I'd be charging a battery bank. In general, larger generators are more efficient (often MUCH more efficient) per unit power produced, as long as you can sustain load within their sweet spot. An over provisioned generator will waste a lot of fuel idling, and an overloaded generator will burn fuel inefficiently. This 'small' commercial generator [https://www.ckpower.com/what-you-need-to-know-about-fuel-eff...] (CK300VM-T4 Final) outputs 225kW, and puts out 14.25 kwH per gallon of fuel (rated capacity). If diesel was $3 a gallon like it is here, thats $.21 per kWh - damn cheap!

So, assuming our friend here is running 24/7 at 2kw continuous using my terribly inefficient setup, he'd be going through 72 dollars a day in fuel. Quite a bit! But let's compare to solar!

A 48kwh system is non-trivial in size and expense. A system rated to produce ~ 40kWh/day in winter (wholesale, DIY installation, no racking or batteries) is ~ 36k, and has 54 large panels. [https://unboundsolar.com/1891324/unbound-solar/solar-kits/17...]

Battery option price varies. Lead acid is cheap, but needs to be over provisioned to avoid stupid short cell life (> 50% discharge will severely shorten cell life), and even overprovisioned if you're actually drawing down the cells much every day, you'll be lucky to get 3-5 years out of them. To have a day buffer (essential, even if you get perfect sunny weather 99% of the time) and not kill your cells quickly, you're looking at ~ $30k worth of batteries on top of that, at nnearly wholesale prices [https://unboundsolar.com/1891324/unbound-solar/solar-kits/17...]

Lithium allows faster charging, deeper discharging, and longer cell life, but is expensive. A ~ 45-50kwh usable battery bank is going to run you an additional $60k at current market prices [https://unboundsolar.com/shop/solar-batteries-backup/battery...], and might not give you an actual full day buffer, depending on how much charge you got in the prior day.

So let's assume we can do free racking somehow (racking and installation costs are often almost as much as a normal system), etc. We're looking at about 66k for a bare bones 'works when everything is perfect' system without much redundancy or backup.

If you split that out over two years, you are paying $91/day, or $19/day more than if you were using that woefully inefficient generator, with a woefully expensive/inefficient fuel, at altitude with all it's associated losses. If you amortize it further over 5 years AND ignore maintenance, racking costs, battery wear, it starts to look like it would win. The reality is, you can't ignore those though.

Unlike the generator, you're also stuck in place (those panels are huge and need to be very solidly anchored), and also unlike the generator the capex is all spent up front. You can't change plans a week in and do something else, you're out that money. Did I mention that the generator I'm talking about cost $850?

Solar has it's place - mainly when you can predict the usage far in advance and can amortize the cost over many, many years (a decade or more).

I get the impression you've never actually had to provision or budget a system like this? I've had to several times.