FWIW, my lithium-ion batteries give me back only 90% of the power sent to them. Last year, my inverters sent a total of 12.0667 MWh to the batteries, and got back 10.8805 MWh. A 10% loss through the process of storing power to the batteries, the batteries holding the charge usually for less than half a day, and discharging the power from the batteries. It'd be a much larger loss if the batteries were expected to hold a charge for months to make it through the winter.
That 10% loss was expected and is within the parameters of me meeting my goals of being 80% energy independent (with me pulling from the grid 20% of my power needs for my all-electric house, including charging the EV which we do most of our driving in).
I'd have to probably double my solar capacity, inverter capacity, and battery capacity to be 100% energy independent. Why that much needed for the last 20%? Because of the law of diminishing returns. It's simply not feasible.
And that's for just a 2-person home (and 2-person driving). Imagine trying to be 100% "green energy" for not just a home, but a city, with large buildings, and large power needs like a hospital building or a manufacturing plant.
And that's with my warm sunny climate in Alabama. Imagine a northern city trying to be 100% energy independent. It'd be ridiculously expensive and even then require a lot of restrictions on their energy consumptions during rainy winters. Going all "green" is just a fantasy.
“I’d have to probably double my solar capacity, inverter capacity, and battery capacity to be 100% energy independent.”
Lived completely off grid for over 12 years. About to go back off grid again. The first important step is just changing lifestyle so that you require less power. Believe it or not, folks once lived just fine without any electricity at all. Reducing demand is the first step to becoming 100% energy independent.
“...about storage in GW instead of GWh.”
In responding to a thread I did some research regarding the amount of energy from windmills vs. nuclear vs. dams. The windmill output was either in peak MW or “supply X amount of homes”. The nuke and dams was usually in MWh or number of homes.”
I think that is to show wind power in a better light and/or to make direct comparisons difficult. One article I read said that it takes 5 times as much wind power MW to equal the same MW output of a dam. Probably estimating an annual average, factoring in that the wind isn’t blowing all the time?