Doesn’t consider storage or transmission. Still, to me a surprising result.
Yes, ignoring the two biggest problems can make any plan look feasible. If we ignore mortgage and energy bills, everyone can live in a Mcmansion!
The article states 40% variation between winter and summer for northern latitudes. This is wrong. More like 4000% variation between best vs worst day. Here in Holland a winter day is 0 to 2% capacity factor.
You cannot install 100 GWp of solar into a 20 GW grid. Such simple facts and logic is lost to entire nations, corporations and billionaires.
My own country of Holland. We have a need for about 120 billion kWh/year, over 13 GWe average draw.
We can probably accomodate some 10 GWp of solar PV with some serious investments in grid upgrades. We have a lot of gas turbines which can accomodate big swings though some plants are must-run, cogen and steel related so that's a problem but let's ignore that to be kind to PV.
We get about 10% capacity factor fo PV. The best systems, ideally angled towards the south, and regularly cleaned get about 11%, but many systems are east or west facing and not so often cleaned so would get 7-9% capacity factor. Let's use 10% as a typical fleet average.
Our 10 GWp of solar PV only generates 1 GWe average on the year. So it provides under 1/13th the electrical energy or some 7% of total electrical demand.
The problem, as you might have noticed, is that we haven't addressed 93% of the problem, which is going to have to be mostly single cycle gas turbines throttled very inefficiently. Almost all coal stations will have to be shut down, which is a good thing on the environmental side, though not much help on the CO2 emissions side, since throttled peaker gas turbines emit almost as much CO2 per kWh as a coal plant.
You will have noticed that the vast majority of this "solar" grid is powered by natural gas, used very inefficiently in single cycle gas turbines.
Now, as a matter of fact, the CO2 emissions would be less if we powered most of the demand using efficient dual cycle gas-steam turbines for mostly baseload and load following service. Ironically, this would have a LOWER CO2 emission than the solar-gas grid.
The main point being that low capacity factor, intermittent, non-dispatchable solar energy sources only serve to lock us into using fossil fuels (very inefficiently) for as long as the solar energy sources persist. Which, I'm told, is forever since it is renewable.
The article states 40% variation between winter and summer for northern latitudes... [Further,] you cannot install 100 GWp of solar into a 20 GW grid.
Conceivably an overbuild of solar could dump peak and lesser generation into on-site storage, with the storage providing power on demand into the grid. For a solar farm to supply "100% solar" power across winter demand, it would need to include storage of about six months of excess summer production. Since grids dominated by solar farms currently use fossil gas backup, getting to 100% requires replacing the backup with massive storage, or they could more economically convert to nuclear backup and still claim to be "100% fossil-free".
Let's compare the two scenarios... At a 40%-varying latitude, a 100 MW capacity solar farm could generate an average of say, 15 MW in summer and 6 MW in winter. Its batteries could at the same time supply the grid with 10 MW on demand year-round, while being topped up across the summer by (15-10) 5 MW, and depleting by (6-10) 4 MW across the winter, leaving only an emergency reserve at the end of season. Ignoring conversion losses, that requires a storage capacity of 5 MW X 6 months. That amounts to 22 GWh, bigger than any battery built so far. Since the peak power between panels and battery would require expensive cables capable of 100 MVA at low voltage, the battery would have to be close by, even on site.
If the owners of the solar farm had enough money to buy such a battery (~22 G$ at ~1 M$/MWh), they would certainly have enough money to buy a 100 MW nuclear power station instead (~0.5 G$ at ~5 $/W), building the solar farm alongside. With the plant now capable of supplying 100 MW on demand, a 100 MVA power line would be justified and the occasional spikes of 100 MW from the solar farm can be injected directly into the grid without a need for storage. Virtue would be satisfied. Regardless of how much the 100 MWp solar farm was actually contributing, the tenfold increase of average power would still be fossil-free. In modern style, the owners would probably market the net 100 MW of on-demand fossil-free power as being "100% solar", with only the fine print admitting to being 90% nuclear.
Sure it's a stunt, but it got me interested. The panels are only 1-2% efficient, and the Model 3 gets something like 6 km per kWh. So the car would take a while to charge. But I love the idea of riding a horse for a good distance and then letting it graze.
Such have the majority of generation both before and after noon, helping to level the generation over the day. This study finds that these panel arrangements are economic provided agriculture can continue on the same lands.