Floating solar PV

I’m a bit late to the party on this one I know. Everyone is out there talking about hydrogen, but I’m thinking about floating solar PV installations.

There are some beautifully impressive images of floating PV systems floating around. They range from looking like really expensive helipads to an undeveloped commercial zone in an old version of Simcity.

Floating PV systems both make sense to me and seem completely bonkers. There are a number of benefits:

• They can make use of previously un- or under-utilised land
• In water-stressed areas they can help to reduce evaporation on important bodies of water. They can also help to limit algae growth, by providing shade.
• At the same time, the cooling effect of water evaporation can help the modules to perform better (as there’s an inverse relationship between temperature and PV performance)
• If installed on water bodies forming part of hydropower installations, there is likely to be electrical transmission/distribution infrastructure already established.

There are a number of challenges though:

• If the body of water is tidal or the system will be subjected to waves, it will need to be factored into the design. The system has to be anchored down, so the anchoring system will need to accomodate this too. And inverter stations/platforms need to be able to designed accordingly.
• The cooling effect above can be lost if the system is compact, not allowing for adequate ventilation.
• Cables. Modules are joined up in series and if you’ve ever been to a solar farm on land you will know that the connection between modules is often not done very neatly. Slack cables looping down low, just begging for an errant sheep to feel peckish. You obviously can’t have this on a floating PV installation. Poor cabling can result in leakage, loss of insulation, corrosion, and snapped and damaged cables. Not to mention safety concerns from live, corroded cables. There needs to be some give though, because cables can’t be too taught in a system that will need to be flexible to move as the water does.
• The system may be visited by different animals too. Anyone who has lived near any large body of water will know that aquatic birds can drop gigantic poos, covering and coating anything or anyone in their way. This can lead to reduced performance of course, but also the development of hotspots on the modules, resulting in accelerated module degradation.
• In general, in wetter conditions there tends to be more corrosion, which could require increased operations & maintenance over time. The system design and material selection would need to take this into account.

This is an interesting document which talks through some of the learnings from a floating PV test bed in Singapore, done by the Solar energy Research Institute of Singapore.

Large-scale reference installations around the world:

• 17MW installation in Piolenc, France. Completed October 2019.
• Singapore is in the process of developing a 60MW project on the Tengeh reservoir.
• 70MW system completed in the Anhui province, China, built on an old coal mining area. Completed end 2018.
• 4.4. MW floating solar array in Sayreville, New Jersey, USA (video below). Completed mid 2019