The producer being able to sell those credits going forward is what made the plant economical to build in the first place.
How are other credits for "new renewable capacity" any different? That new plant is going to be producing renewable energy and selling renewable energy credits for long after it gets built. The projected returns from selling those credits is part of the financing they used to build it.
If more people are trying to buy RECs, the market value of those RECs goes up, and it enables more producers to invest in new renewable capacity because they'll be able to sell RECs for more money.
Of course the additional credits on the market could push prices back down if a lot gets built (woo fucking hoo, that's what we're trying to encourage!), and the market demand for more credits to purchase is also increasing as governments pass requirements for XX% renewable capacity by YYYY year.
A short summary:
1) A producer gets a REC for putting 1 MWh into the grid from renewable generation. This energy mixes in with all the other energy on the grid, it doesn't go anywhere in particular.
2) The producer sells this REC on the market.
3) The consumer who buys the REC is considered to have purchased renewable energy, either to meet renewable energy requirements or just for their own personal reasons because it's a good thing to do.
In 29 states, DC, and PR, they have "Renewable Portfolio Standards" which require electric suppliers to have a certain amount of renewable energy in their production portfolio. They can own this production capacity and make the RECs themselves, or they could burn natural gas and buy a bunch of RECs from a third party, or even a bunch of people with solar panels on their roofs.
Beyond those 29 states, people also buy them just to say "We run on clean energy." A friend of mine has an electric car and buys renewable energy to go with it. Did the actual electrons in his car come from a wind turbine? No, but he's helping make wind power more economically viable through the renewable energy credits.
Same thing with switching to renewable energy. Higher demand pushes prices up and therefore fuels innovation and development of new projects.
I don't see this making any difference for the company itself (except the PR benefits and on the negative side the costs). The real benefits come from actually reducing carbon emissions. It is possible we will in the future have something like a carbon tax. If this happens, companies that have already cut their emissions have an advantage. Also, this can start affecting the share prices already earlier as investors will start counting in the possibility of carbon tax happening.
Disclaimer: I have no idea how carbon intensive their production is. In some industries, the actual emissions are meaningless and true carbon opportunities/risks lay elsewhere. In the case of Bosch, it might be for example the switch from developing technology for combustion engines to electric cars that has the real effect.