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9 January 2020

Vietnam to accelerate floating solar in conjunction with Hydro

The largest floating solar project in the world so far is either the 70 MW installation by Ciel & Terre in Huainan City, China, or the 100 MW Weishan Jining 1, built by Sungrow, also in China. So when a headline suggests that Vietnam may build out 400 MW, it is worth taking note.

As usual it is not a single installation and it is not yet actually built. We already know that the Saemangeum Seawall Phase 1 in South Korea, will be the largest single installation once complete, but that is scheduled for 2022, along with the second phase in 2025 for a further 900 MW, and Indira Dam in India is scheduled also for 2022, and 1000 MW. So we know which will be the largest in 3 years, but today ambition in size remains very interesting, especially for a country as electricity hungry as Vietnam.

It turns out that the headline masks the fact that this is two separate installations, to be auctioned this year and next, for up to 100 MW and then a further 300 MW. They will still be landmark deals in the creation of a solid floating solar industry, which currently remains in its infancy with global installations at about 300 MW a year up to last year. Rethink recently published a report suggesting that floating solar would reach 61.6 GW by 2030 from just over 1 GW today, but mostly in partnership with existing hydro facilities.

This report made the point while there are many benefits to floating solar, there are a number of extra benefits when it floats on a hydro plant reservoir – for instance transmission is already in place and if the two resources – hydro and solar – are controlled together, then a higher baseload can be demonstrated from the two combined, than the solar on its own, makings its output more valuable in capacity markets. Effectively the hydro becomes the battery storage overnight when the solar power stops.

The fact that Vietnam is going down the hydro partnership route is also interesting, as it shares many rivers and sources of rivers with China, and the building in the last ten years of 22,000 dams in China, has lowered water levels in many Vietnamese rivers. If solar picks up the slack during the day, this set up allows more water to remain higher, above the dams, for longer.

Sunpower once told us that it had seen a hydro reservoir run dry, and the solar continued to produce strong electricity while sat on the bottom of the reservoir, until it filled up again – so no daytime blackouts, when you use solar as well.

The auctions were first signaled in October when the Asian Development Bank made a $37 million load to finance the first solar plant. In December more news of how the auction would function came out and when it would go ahead, and sought help in the process from international agencies.

Recently Vietnam has already commissioned a 47.5 MW floating solar project at Da Mi hydropower plant in Binh Thuan.

The idea now is to select an EPC partner which has done this before, and we’re sure the same names will crop up Ciel & Terre, from France and China’s Sungrow, and then accelerate floating solar in the country.

The first project will be around 50 MW to 100 MW and then in 2021 the country will go for a larger one at around 300 MW. Both plants will be located at hydro facilities belonging to the national electric utility Viet Nam Electricity.

It was China that perversely showed how floating solar on reservoir dams could work in conjunction with hydro, but did it with a solar installation on top of a nearby mountain, rather than a floating system at its Longyangxia dam. This dam offers some 1.4 GW of hydro capacity, on the Yellow River in Gonghe County, Qinghai Province and was partnered with 850 MW of ground standing solar, and the two work tightly in parallel, to deliver an enhanced baseload over the same transmission lines.

The more examples of this tandem system working will mean the idea spreading faster, and Vietnam has 17 GW of dams it can then transfer the idea to. Given Vietnam’s annual electricity requirement is growing at 9% to 10% a year, and the government has targeted Vietnam’s power generation to rise from 48,600 MW to 129,500 MW by 2030, every source of energy is going to count. Vietnam has a budget of some $6.7 billion a year to expand power generation, and large projects are best.

A report out last year said that 47 of Vietnam’s 62 electric generation projects above 200 MW are up to two years behind schedule. So quick wins are essential.

But to ensure this electricity growth is achieved using zero carbon will be tough, given that Vietnam has no internal solar skills whatsoever, but went from 100 MW of solar in 2018 to ordering a further 4.4 GW of solar through 2019. Essentially it is relying mostly on its neighbor China and the Asian Bank, for helping hands.

The 300 MW floating solar facility is planned for the Hàm Thuận Hydroelectric Power Complex, a cascade of two hydro power stations, which has just 300 MW of existing hydro capacity, and this phase will double that.