You are probably technically correct, but most people don't need 24hr internet access, so that one 400 watt panel would provide high speed internet for let's say 12 hours a day and that's plenty for this odd scenario of living in a place with no power but still needing high speed internet.

The claim was 24/7 powering with "a 400W panel and some batteries" - which is simply false.

I deal with the realities of off-grid power in my office on a daily basis, and a vast majority of what's written about solar and batteries by people who don't have experience with them is simply wrong. I try to correct it where I can.

With a 400W panel and a few kWh of batteries, you could reasonably accomplish 14-16 hours of access during peak sun in the summer, 8-12 hours in spring and fall, and 0-3 hours in winter, except for 5-6 hours on sunny winter days.

Although I've heard that the newer Dishys use somewhat less power (50-70W), which does improve things.

Ah the joys of hiking 1000ft up a mountain in subzero temps through 4' drifts to clear ice off the panels. Although, for the most part I've found that provided you pitch the panels at 50 degrees or so, snow tends to slide off. The battery system has to be able to carry the load through 48h of zero panel output at least to let snow clear. In 20 years I've only had to physically clear ice off the panels three times.

48h is less than 5 kWh of batteries, one quarter of what the parent post proposed as the absolute minimum.

It will depend somewhat on the area, and you can trade panel area for battery pack capacity to a reasonable extent - but you either need a lot of panel area to power you on dark days, or you need a lot of battery to ride through those periods. Out here, at least, we'll have a week where my 5kW of panel on my office produces less than 1kWh/day, often rather significantly less.

The problem is that after 48h, then... what do you have? You need to have either enough panel area to both run loads and charge the batteries, often in dim conditions, or you need a lot more battery.

Doing reliable off grid power takes a lot more than most people who haven't dealt with it assume, especially if you're dealing with serious winters and don't want to light a generator.

I'm basing my estimates off what it would require for me to run 2.4kWh/day, year round, without generator, on my office system - and it takes a LOT. I have 5kW of panel, 10kWh of battery, a typical winter day load of around 3kWh (base loads + minimal compute loads for a work day), and I still require a couple gallons a year of gas to run this reliably. Depending on the winter, I go through 3-5 gallons of propane for heat as well, though I've been trying to move to kerosene - more efficient, as I can run a lantern as a combined heat/light plant on my desk, and heat my hands, which are the only real constraint on cold temperature work in there.

I know those numbers sound somewhat nonsensical for a 100W load, but I literally make a living in an off-grid office...

How on Earth you would need 20+kWh of batteries for a system that even run 24/7 uses 2.4 kWh? And absolutely doesn’t make sense to run it 24/7, even when no one is using it, if you are running it off grid.