Is there some upper limit on how many wind turbines and solar panels that one can build?
Well, obviously there is; These things use raw materials that are not in infinite supply.
But there is a (probably much lower) limit to the number of these we can
practically build and use - The avalability of suitable sites is also not infinite.
And there's a much lower still limit to the number we can
economically build, though that's a moving target, and depends on a large number of factors, only some of which we can control and/or predict.
With any electricity generation technology, the economic questions are:
1) Is the electricity it produces sufficiently valuable to more than pay for the cost of building, running*, and finally decommisioning the facility? and;
2) Is there another way to generate the same value of electricity that is cheaper, after including
all costs**?
It is far from obvious that all new wind turbines and solar panels will (at least in the immediate term) meet the hurdle of condition 1; And the more of these intermittent generators you build, the less easy it is for them to meet the hurdle of condition 2.
Electricity cannot be cheaply stockpiled, and this is reflected in the wholesale prices paid for it by energy grids. It is very common for wind and solar energy (and less common, but not particularly unusual, for other energy projects) to be subject to sale price guarantees, so that the grids they feed must buy their electricity at a pre-agreed price, even if the prevailing wholesale price is far lower.
This (along with inertia from less dispatchable sources) can lead to negative wholesale prices. In a very real sense, adding more generation to a grid with negative wholesale prices, is worse than useless. The average value of electricity from a generator must be greater than the amortised average costs of that generator, or it is economically unviable, and building it was a literal waste of money.
A grid with large amounts of solar power can easily reach this economic saturation point - where each new solar panel added is of negative worth, as the average value of its electricity is less than the cost of making and installing the panel.
Lots of obfuscation and accounting trickery is used to avoid this from being easy to detect; But it is almost certainly already the case for many regions, such as California and South Australia. In both of those states, they have neighbours with lower proportions of solar power, who can help to conceal the local saturation by trading low value solar electricity for high value fossil fuel generation; And they also trade off in this way internally, using their own gas fired generation - though that internal trade off has an undesirable impact on their claimed carbon emissions.
Californian politicians get great support from citizens when they reduce their state's carbon emmissions; But nobody wants to talk about how much Californian consumers are pushing up the carbon emmissions of Arizona or Nevada. The same is true for South Australia, whose "green" status is, to a great extent, dependent on making Victoria's status more "black".
There's a very real economic limit to the number of wind and solar generators we can build. It's hard to pin down, and varies depending on the costs of storage, and on the net cost of selling low value electricity to neighbours, and buying back high value electricity from those neighbours (buying expensive and selling cheap isn't a great business model for any product or service). Both of these costs themselves depend on the pattern of consumption, which can be varied either by encouraging industry to follow the supply curve, or by load shedding; Those techniques have political and economic costs of their own, so determining where the line, whether it has been crossed, and whether it can be profitably and practically moved, is is very difficult indeed.
The wholesale electricity generation and marketing picture was a horrible mess before large scale intermittent generation was a thing; It's even messier now, and there are few simple solutions, and even fewer politically palatable ones.
* Including the cost of fuel, and the cost of disposing of any waste products.
**Ideally, without externalising any of these costs; Although in our real world, many costs are externalised - the most glaring example being the cost of climate change caused by burning fossil fuels.Electrolysis of water
️ -> 2H2 + O2
-> CxHyOz + (2x-z)(H2O)
