Melbourne-based solar plus storage developer RayGen Resources says it has brought in international solar project developer Photon Energy as a minor equity partner, and has plans for a huge 100MW/1,000 MWh solar plus storage project.

RayGen recently secured $3 million in funding for a pilot project of what it calls its “solar hydro” storage technology, which captures sunlight with mirrors and stores energy in water. That plant, near Carwarp in north western Victoria, will provide 4MW of solar power and 3MW/50MWh of storage.

The latest announcement says that Photon will take an unspecified equity stake in RayGen (believed to be less than 10 per cent) and act as project developer and EPC contractor for the projects it plans to roll out in Australia and elsewhere, including the aspirational project for a 200MW solar plant with around 100MW/1000MWh storage.

Photon Energy’s CEO Georg Hotar said: “Our investment in RayGen is our first step into the upstream segment of the solar industry and it comes at a crucial time,” Photon Energy CEO Georg Hotar said in the statement.

“The elimination of solar energy’s intermittency and ensuring its 24-hour availability at grid-competitive cost is the holy grail and RayGen has found it.

“Our partnership with RayGen will enable us to address a vast new universe of opportunities both on-grid as well as in off-grid remote locations including islands.”

Michael Gartner, the head of Photon Energy in Australia, said RayGen’s PV Ultra solar module had proved itself as the most efficient way to convert solar energy into electricity. “Combining high efficiency concentrated PV generation with thermal absorption and storage, it achieves the highest energy density of any solar technology available today.”

He told RenewEconomy the technology is a massive step forward providing cost effective base load, inertia and on-demand power, and on-demand power was becoming significantly more valuable than both “base-load” and variable renewable power. Storing heat was less efficient, but significantly lower cost than storing electricity in a battery.

“We will see very interesting LCOEs (levelised cost of electricity and storage) from this technology,” he said. Gartner said plans for a project the size of 100MW and 1000MWh were advancing, but said it may not be located in Australia.

The RayGen technology combines its proprietary PV Ultra solar technology – which co-generates electricity and heat – with a tailored electro-thermal storage cycle, called “Thermal Hydro”, that uses existing industrial equipment to deliver high-performance, low cost electricity storage.

PV Ultra generates electricity and heat from sunlight focused onto a tower-mounted photovoltaic receiver. The PV Ultra receiver contains around 400 PV Ultra modules, each generating 2.5kW of electricity and 5kW of heat. The total is 1MW of electricity and 2MW of heat for a combined 3MW of power per PV Ultra field.

It says PV Ultra is a modular system and can be scaled up and scaled down in 1MW units to suit a variety of projects and customers.

The storage component, also known as “Thermal Hydro” –  takes advantage of PV Ultra’s capacity to cogenerate electricity and heat, and stores thermal energy in two insulated water reservoirs with a 90°C temperature difference.

“RayGen has adapted a thermal storage technology widely used in northern European district heating systems for this unique electricity storage application,” the company says, “When required, firm power is dispatched through a thermally driven Organic Rankine Cycle (ORC) engine, a proven generation technology utilised in geothermal generation systems.”

RayGen CEO Richard Payne says moving toward 100 per cent renewable energy will require storage solutions that can store power cost-effectively for hours, days or weeks and be deployed at large scale around the world.

“With the calibre of Photon Energy’s team and their breadth of experience with developing and operating solar projects worldwide, RayGen’s technology can soon be operating across a range of countries and sectors, helping to make the shift to renewable baseload power a reality,” he said.

RayGen’s partners in the Carwarp project are utility AGL and engineering firm GHD. The solar power plant will provide Australia’s National Electricity Market with day-night renewable electricity and supply synchronous power where it is critically needed in the West Murray region.