Review of Discussion Paper On “Agrivoltaics In India”: Challenges And Opportunities

 

Preamble : 

International Institute for Sustainable Development or IISD issued a discussion paper titled “Agrivoltaics in India: Challenges and Opportunities”.

This background paper assessed the current state of development and identifying the challenges and opportunities for commercialization of agrivoltaics. It reviewed existing literature on agrivoltaics and interviewed 11 experts from power distribution companies (DISCOMs), research institutions and commercial firms who have implemented agrivoltaics pilot projects.

 In the context of “Agri-voltaics”, the discussion paper was shared with me to review and give my comments.

Disclaimer:

The comments and views expressed here are in my personal capacity as an independent practitioner. The views and comments expressed here need not be the same as the institutions i am involved with. The views expressed here are based on studies and experiments conducted by me and may not be universally applicable (or even right). 

Understanding Agri-Voltaics :

The discussion paper discussed various definitions and topologies of Agri-Voltaics. These are mostly based on type of mounting structure.

Comments :

1. All the definitions discussed more or less means the same. That is using the same space for Agricultural activity as well as solar power generation.

2. Rooftop Agri-Voltaics is conspicuously missing in the topologies that are being discussed.

3. Overhead PV : One of the Topologies discussed is “Overhead PV”. Though this sounds like the best fit method for Agri-PV, it may pose many challenges. Here are a few of them. 

1. Over head PV requires very elaborate structural design: Since the height of the structure is long and span (Distance between two columns) is large (for movement of machinery and people) , the structural engineering becomes very specialized .

2.  Difficulty in Maintenance and cleaning : Field data and field experience shows poor and sometimes nil maintenance in standard low height solar structures. Even rooftop solar panels are not cleaned in most cases. When Solar panel cleaning is a challenge even in normal low height structure, How can Cleaning be ensured for tall structure ? In case of Overhead PV, since solar panels are not visible and if the cleaning in not uniform, it may lead  to hot spot formation and quick degradation of the panels .

3.  Availability of water: Solar panel cleaning requires plenty of water . In the context of India, water availability for panel cleaning poses a challenge. More so, in case of Overhead PV, Water will be required to be delivered under high pressure to reach the height. This requires heavy duty pumps and water availability in the aquifers. [In states like Karnataka where power is free for agricultural use, accounting for this power poses a challenge].

4. Quality of water : In many parts of Karnataka, the underground water, particularly in deep confined aquifers , the water quality is a serious challenge . Water from deep aquifers will be generally hard and may not be suitable for panel cleaning. Using hard water for panel cleaning will lead to scaling on the glass leading to degradation. It may be the same case in other parts of India. 

Solutions and opportunities 

While experiments on overhead PV must continue, Cultivation below low height structures and in the peripheral regions of the solar panels presents a good opportunity .

1. Choice of Crop :  Like how there are geographical variations in crops cultivated, there will be and should be variations in crops cultivated under solar panels in different geographies.

Elevating structures for growing crops like millets, paddy and wheat may not justify the cost. It would be better to look at cash crops and vegetables that have higher economic return per acre. 

One can consider Cauliflower or cardamom to be grown under the solar panels. These are high demand, high value crops & at the same time require less sunlight and water.

Another example can be coffee, which likes humidity. This can be grown in the peripheral areas.

Pepper is another crop which can be considered. As a creeper, this can be grown along the structure columns.

Foliage crops like cabbage or lettuce will grow better under solar panels than under full sun. (The plants in the process of seeking sunlight will tend to have broader and greener leaves).

Crops like tomatoes, strawberries which love mild climates will perform better under solar panels .

2. Higher Yield from Solar Panels :  Having vegetation near and below solar panels has a very positive impact on solar panels . Higher moisture and sweating of the leaves cool down the panels increasing the yield.

Below is a case study comparing PV and Agro PV

 3. Rooftop Agro-PV: 

The discussion paper is conspicuously silent in respect to Rooftop PV.  

However, a reference is made under the heading “Intended benefits and potential risks” where it states that , “the availability of land is one of the main constraints faced by developers participating in the PM-KUSUM scheme”.

Rooftop Agri-PV is a good concept which can ease the pressure on the
land. It is expected that by 2050, half the population of the world would be living in urban areas. This would mean a huge pressure on the energy infrastructure as well as agriculture. Rooftop PV can be the answer for both.

Also , many of the challenges in ground mounted Agri-PV can be overcome in rooftop Agri-PV. For
example, the challenges of cleaning or the challenges in safety related to cabling. 

As pointed out in the discussion paper, The primary benefit of agrivoltaics is the “increase in land-use efficiency leading to a higher total output from a given piece of land compared to farming or energy production done in isolation”.

Rooftop Agri-PV is the best bet to achieve this. Both energy efficiency and Agri efficiency is maximum in rooftop Agri PV .

Rooftop Agri-PV also allows maximum flexibility in Agro designs. That is maximum vertical and horizontal space can be used for growing crops which is not quite possible in ground mounted Agro PV set up. 

There are host of other benefits in Rooftop Agro-PV. Circular economy , Rainwater harvesting, Lower carbon footprint, Higher Agro and energy yield to name a few. 

Potential Risks :

The discussion paper has covered a few major risk factors in deployment of Agri-Voltaics . Below are few more risk factors which I feel must be carefully evaluated.

1. Risk of Flooding : 

Deployment of Agro-Voltaics can substantially increase local rea run off and may even lead to flooding.

Below is an example of how setting up Agro PV system will lead to higher Run off

Parameter	Agricultural Land	Agri-PV land
Area	1Acre or 4046 m2	1Acre or 4046 m2
Area Under PV	0 Acres	0.5 Acres or 2023 m2
Run-off Coefficient	0.4	O.4 for Agri land and 0.85 for PV panels
Annual rainfall	500 mm	500 mm
Annual run off	(4046 x 0.4 x 500)= 809 KL	(2023 x 0.4 x 500) + (2023 x 0.85 x500 ) = 1264 KL
Percentage increase in Run off	56 %

 The example above is a conservative estimate with average annual rainfall of 500 mm. Most parts of India receive around 500mm or higher than 500 mm of rainfall. Higher run off also means lesser ground water infiltration. That means more pressure on local aquifer for irrigation and domestic use. 

Opportunity :

Higher run off from Agri-PV lands also means it is an opportunity to harvest the water. Well defined run-off gives an opportunity to contour the land and install recharge wells which can lead to augmentation of ground water. if harvested properly, the same water can be used for irrigation. 

2. Electrical Safety : 

This is perhaps the greatest risk in Agro PV setup. The Energized DC and AC cables pose a serious threat to livestock as well as farm workers. Body grounding from DC cables coupled with moisture around the structure can be very serious.

3. Skill Deficit : 

Agriculture itself is a tough science. PV is also a specialized branch on engineering. Therefore, In India, for scaling up of Agri-voltaics, we need very skilled manpower with experience and expertise in both Agriculture and PV. This is a challenge as well as a huge opportunity. 

Outlook and Concluding Remarks : 

1. Agrivoltaics definitely has a huge potential and is good bet for developing economies like India.
2. Coffee and pepper growers are good starting point for scaling and testing Agri-PV.
3. Development of standards are required.
4. Rooftop Agro-PV systems need more focus and encouragement.
5. Demonstration sites for Land based Agro PV & rooftop Agri-PV is required.
6. Land along the railway lines are good cases for demonstration and popularization of Agri-PV.
7. Practice of Rainwater harvesting should be encouraged along with Agri-PV.
8. Land laws need to be reformed for quick scaling of Agri-PV.
9. Agri-PV must be viewed holistically in the over all context of circular economy and sustainability.
10. Demonstration sites must be small (around 1 Acre) and must be accessible to public. It must be like an experience centre rather than a research project site.
11. Working groups must be encouraged to study successful pilots around the world. 

 

 

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