V16 emergency lights

Is it compulsory by law to replace the triangle warning signs with this new V16 emergency lights in case of a break down by the road side?
where to get one?

Yes for Spanish registered cars from 01 Jan 2026.
It's not just any cheap becon either. It has to be able to transmit to the DGT 3.0 connected vehicle platform.
If you get one from a reputable supplier, it will be fine.

It is recommended that drivers retain the triangle because if on a bend oncoming  traffic might not see you until too late.

True of false I am keeping mine 

No, you don't have to replace the triangles but you must carry a V16 light as well. Loads of place sell them including Carrefour, AlCampo, many DIY shops, FueVert, NorAuto, Amazon and so on. Just make sure it says V16 and DGT compliant. 

You can't use triangles on the motorways but they can be used on other roads.