Rough estimation of the potential floating solar power projects in Indonesia

On November 9, the 145MW floating solar power project at the upstream reservoir of the Cirata hydropower station officially entered commercial operation. The Cirata hydropower station, with a capacity of 500MW, is presently Indonesia's second-largest hydropower station (the largest being the Saguling hydropower station upstream at 700MW). Additionally, this solar photovoltaic project is the largest of its kind in Southeast Asia.

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Constructing floating solar panels on the upstream reservoir of an existing hydropower station offers several advantages:

1) it utilizes the existing reservoir area, saving valuable land and avoiding substantial land acquisition costs and related social risks;

2) it reduces reservoir water evaporation, benefiting hydropower generation;

3) the water surface helps cool the solar panels, enhancing the efficiency of solar power generation;

4) integrating photovoltaic power generation with hydropower provides more stable electricity output;

5) it leverages the existing transmission and distribution facilities of the hydropower station, saving corresponding investments.

The primary advantage among the mentioned benefits is the cost savings in land acquisition and avoiding the risks/losses associated with land disputes and project delays. In the equatorial conditions of Java Island, each megawatt of ground-mounted photovoltaic installation requires 0.8-1 hectare of land, with a land price of approximately 840,000 USD per hectare. A 100MW solar photovoltaic power station occupies about 80 to 100 hectares, with land acquisition costs ranging from 67,200,000 to 84,000,000 USD, making the cost skyrocket. In reality, Java Island, which accommodates half of Indonesia's population, does not have sufficient land to offer.

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Combining with Indonesia's recently announced Comprehensive Investment and Policy Plan(CIPP), Indonesia aims to build 40400GW of intermittent new energy (solar and wind power, etc.) by 2030. Floating solar PV power is gaining momentum. There is good potential here in Indonesia. For example, a series of floating solar projects are being developed or planned around Banten Island to supply green electricity to Singapore; the Sepaku Semoi Dam, providing green energy for the new capital- Nusantara, is also under construction with 100MW of floating solar power (please see my previous article: Indonesia's Capital Relocation: Utopia in Borneo or a Century’s Grand Plan for the Archipelago Nation?). The vast Lake Toba also has the potential for numerous floating solar projects (please see my previous article: From Asahan River to Kayan River: Reflections on Driving Industrial Upgrading in Indonesia through a River), along with hydropower stations being operated by PT. Vale and big lakes over there in South Sulawesi, among others.

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So, what are the other floating solar PV projects like Cirata specifically in Indonesia, integrating hydropower and solar PV? Let's do a quick calculation.

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Based on data from the Cirata 145 MW floating solar PV power plant, it occupies 250 hectares (Ha) of water surface area. Using this data, we can figure out the area occupied per unit of installed capacity: 250 ha / 145 MW = 1.724 Ha / MW. According to the latest regulation from the Indonesian Ministry of Public Works and Housing (PUPR), the area for a floating solar power project can occupy in a reservoir is up to 20%. Therefore:

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Potential capacity of floating solar power plant = Reservoir area X 20% / 1.724

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According to data from the Indonesian Ministry of Public Works and Housing and the above calculation method, there are 14 hydropower stations in Indonesia with floating solar power capacity of over 50MW (including the expansion of the Cirata floating solar power), with a total installed capacity up to 11907MW.

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