Most storage will be built after there is renewable capacity to charge it from, therefore available to build it with.

I can see it if it’s purely domestic end-to-end.

But at least in the US, we have a bad habit of outsourcing our problems away: Out sight out of mind.

If there’s any significant portion of the build out that’s non-domestic, then I have reservations.

Nobody gets a price break on their power bills when they make panels or batteries, and nobody pays for it and fails to pass on the cost.

Every single kWh that goes into making any piece of kit, whether battery, wind turbine, solar panel, e-car, or what-have-you goes onto its price tag.

I don’t mean price breaks.

How does one account for manufacturing and mining that is offshored, to ensure that they don’t use fossil fuels (like coal) in their process?

It’s the manufacturing analogue of organic food certification.

If you have any pull, feel free to liberally use this as your own :)

By the time much storage is being built, renewable power will be the cheapest choice, by far. So, you are worried that somebody up the line will choose to use expensive fossil-generated power instead of cheap renewable power.

Just by preferring the cheaper product, you bias your choice toward being made with renewables. It is not a guarantee, but in aggregate it is good enough.