True, but...

From the server's data: Power used 2.62W

With these figures they could easily rely on used solar panels and batteries, therefore adding nothing to the environmental cost of building new ones and reducing the impact of recycling them by increasing their active life. Gradual repurposing of used cells and batteries to less demanding uses should be always considered before sending them to recycling. I do this all time with normal batteries, including non rechargeable ones such as alkalines: a battery that can't supply a toy with motors anymore will likely work in a small radio, and the one which is becoming too weak to supply a radio can work for some months in a TV remote.

Embodied carbon is amortised over time, and is not considered for the Spanish grid comparison, as noted in the article, unless I missed it later on?