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Comment by zertrin | Hacker News Reader

GW and TWh are not the same unit. You need to multiply by the hours of effective sun in a year (and applying some reduction factor for the fact that there isn't 24h of sun every day, nor that the full production capacity is reached)

Even if that doesn't cover the energy demand, the number is not negligible for 438 GW of capacity. Assuming that the effective full sun equivalent in terms of energy production is only 10% of a day in average, we get: 24 h/d × 365 d × 0.1 × 0.438 TW = 384 TWh

I have no idea about the 10% factor, someone more knowledgeable can coreect me, but, we are not speaking thousands of years if the growth continues before the full energy production value is getting close to the energy demand.

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In 2022 the US had ~143 TWh of utility scale solar PV [1]. Utility scale solar PV had a nameplate capacity of ~71 GW [2]. So, the average US capacity factor for utility installations is ~0.25.

Or, for simpler calculations, just multiply nameplate capacity by ~2,000 to get the expected annual generation in Wh.

[1] https://www.eia.gov/electricity/annual/html/epa_04_03.html

[2] https://www.eia.gov/electricity/annual/html/epa_04_03.html

> I have no idea about the 10% factor

As a single data point in California, the factor for my solar installation was 15.4% for the last twelve months, so your guess seems pretty reasonable

0.1 is reasonable, allowing for cloud cover and dust films reducing output. Maybe a bit high because often panel nameplate output exceeds capacity in other parts of the chain (inverters, grid export points).

But the 438 number should be 180. Cleantechnica is perpetually over-optimistic. Today, we have 180.

Left implied in the original post, but let's make it explicit: we also want folks to switch from ICE to EVs, and the grid is going to have to increase capacity by an order of magnitude to service all of those. We can't yell "EVs are the future" without understanding that that also means we need vastly more electric power than there is today if we also want people to be able to rely on having power at all times. Because EVs don't charge "throughout the day", they get plugged in at night, all at the same time, and good luck with that on the current grid.

Even if 40GW per year gets us to the current coverage in a hundred years, that's not the target. The target needs to be 400GW a year _at the very least_ and realistically it needs to be a terawatt+ if we want to see it happen in our lifetime.

The target isn't today's grid capacity, nor today's usage. It's the one we can expect 50 years from now. Because public infrastructure gets updated at a glacial pace, and charged at "take what we quoted you, double it, then double it again because lol bribes that you can never prove" practices everywhere.

Americans drove 3.19 trillion miles last year. EVs can go ~3.1 miles/kWh, so if we swapped out all the vehicles for EVs, they'd have consumed ~1 PWh in electricity. That's 25% more electricity than we generated last year.

The total US nameplate generation capacity is just 1.3 TW - including mothballed generators, so I'm not sure why we'd need to add 400 GW of capacity per year let alone get to tens of TW of generation capacity.

Admittedly, solar can't generate electricity all the time, but even with a modest 20% capacity factor, it'd take about 600 GW of solar to generate 1 PWh of electricity per year.

Moreover, we rarely come close to using 100% of our existing generation capacity, outside of a few hours during hot summer days. EVs, being well, energy storage devices that are stationary the vast majority of the time, seem well suited to charging whenever we have excess supply - which is again, most of the time.

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