The JV, Forsa Energy, aims to develop projects in the UK and across Europe, the new company said.
It has a combined current portfolio of 375MW pre-construction onshore wind farms — 150MW of consented projects and 225MW in advanced development — and a "fully consented 400MW pumped storage scheme being developed in conjunction with partner Buccleuch", Forsa said.
Chief executive of the new company Alan Baker explained: "Old coal-fired stations are closing down, we’ve got increasingly cheap but intermittent renewables, plus an electric vehicle revolution on the horizon — so we’ll see lots of peaks and troughs in energy supply and demand.
"Every country in Europe will need an energy mix that is low carbon and very responsive.
"The great news is that all of these technologies can be delivered at zero or very low subsidy, and — if you put them in them in the right combination — they can deliver very stable low carbon energy far cheaper, and just reliably as other forms of baseload generation."
Velocita sold its French onshore wind portfolio, which included a 500MW project pipeline, to Envision Energy in December 2016.
The sale, and the backing of private equity firm Riverstone, has given Forsa "substantial equity capital", it said.