While solar energy has been tackling the world's most pressing challenge at this point in human history, by providing a clean and renewable source of energy, it is also creating another problem that is harming the climate in other ways: Land spaces that could be used as farmlands or grazing reserves are disappearing under utility-scale solar panel installations. The fate of the world's arable land is becoming a major concern even as global population booms and the demand for food booms with it. Currently at 7.5 billion, the global population is estimated to reach 9.8 billion people by 2050. Food production is expected to double by that time. Ironically, as population grows, energy demands also grows. This means that both electricity and agricultural needs will put more stress on the world's land reserves.
What Are Solar Farms?
Solar panels have become 'cash crops' in their own right with their own 'farms' except that they generate electricity instead of food. A solar farm, or solar power station or solar park or solar power plant is a large-scale, and sometimes, grid-connected photovoltaic power system designed for the generation of retail electricity. Solar farms typically are large arrays of electricity-generating solar panels connected together for production of electricity and distribution. They are mostly mounted on the ground instead of on rooftops. Solar farms are often classed into 'utility-scale solar farms' and 'community solar farms'. The difference between the two is defined mostly in terms of size; utility-scale solar farms are much larger than community solar farms.
Community solar farms or mini-grid generate electricity for sharing among members of a local community. They are mostly grid-tied. In comparison, utility-scale installations are grid-tied as well but they are to be distributed and used at far distances from where they are produced and so have to be transported over long high-voltage power lines. They therefore, take up tremendous amount of land spaces and could disrupt local biodiversity.
Agrivoltaic Solar Farms: Misfits of the Solar World
Agrivoltaic systems or agri-photovoltaics (Agri PV), integrate agriculture with photovoltaic systems. The objective is to balance the loss of land space by seeking and balancing agricultural benefits and electricity production. Since both solar panels and plants depend on sunlight to perform their functions, by coexisting on the same land space, the two share the same energy source and land space for useful production without cancelling each other out. In this way, sunlight is harvested twice, first in crop production and second, in electricity production.
The Catch
Agrivoltaics is simply farming on the land space under and/or between an array of solar panels. Since plants require access to direct sunlight, crops that can be farmed under low light are mainly specialty crops, like vegetables, tree nuts, dried fruits, horticulture, nursery crops and flowers. Examples include spinach, tomatoes, onions, potatoes, honey, coffee, garlic, ginger, groundnuts, ginger roots, carrots, etc. These crops are often intensely cultivated or managed and used by people for food, medicinal purposes, and/or aesthetic gratification.
Agrivoltaics have also been used to include agricultural activities like the grazing of sheep in solar parks as well as conventional electricity production practices on farms, for instance, the installation of solar panels on the roofs of barns. There are three types of agrivoltaics that are being used all over the world and are being actively researched
1. Planting rows of crops under stilted solar arrays
2. Planting crops in spaces reserved in between solar arrays
3. Greenhouses made from solar panels.
The Benefits
Technological innovations in genetics, breeding, pest management, farm vehicles have led to tremendous agricultural success all over the world. In all instances, agrivoltaics have had positive impact not only on the conservation of land space but also on crop yield, water consumption and produce quality.
Solar panels remove direct light from soil spaces and crops planted in them. This has been shown to have positive impact. They help the soil underneath them retain more water and lowers soil temperatures. In places where this effect has been studied, the amount of irrigation water was reduced by 50%. Naturally, this increases yield and reduces operation costs. There have been claims of up to 30% increase in yields. Conversely, the crops and the cooler soil underneath the solar panels at lower temperatures. This improves their performance.
The Drawbacks
At the present, the drawbacks of dualizing land use outmuscle the benefits.
For one, agrivoltaics will only work well for shade-resistant plants that require shade that grow in lowlight. They represent only a tiny percentage of agricultural productivity. Majority of cash crops do not farewell in a lowlight environment and are not compatible with agrivoltaics. The successes have been with non-cash crops so there's still not enough to justify the cost of investment.
Agrivoltaic greenhouses have been dismissed as inefficient and unprofitable. It requires a massive upfront investment, not only in the solar arrays, but in different farming machinery and electrical infrastructure. Farm machinery can also damage the infrastructure and add to the cost of investment. This does not compare favourably to conventional solar panels or to conventional farming methods.
Also, photovoltaic systems are technologically complex. This means that operating them requires a pool of professionals and experts. This adds significantly to the costs of the systems.
Conventional agricultural methods is generally more profitable. This lowers the attraction to agricultural entrepreneurs.
More Realistic Alternatives
From a different perspective, the problem of the loss of land can be solved with more efficient solar panels. Higher-efficiency solar cells can harvest more sunlight per installation space. In this way, more energy can be captured in lesser land space. At the present, the highest efficiency of any solar panel in the market is still at 22%. Those solar panels, though considered of premium quality, can only capture just 23% of incident sunlight. A solar cell that can be 80% efficient would take up just about a quarter of the space existing solar panels take up. The industry's greatest efforts are in this direction.
Also, using vertically mounted bifacial solar panels in solar farm installation can help conserve space. Bifacial panels have seen a surge in popularity in recent years. According to a 2019 report, by 2024, the size of the bifacial market is poised to increase tenfold. Read full report here. Regardless, bifacial panels are still limited by low efficiencies and will benefit greatly from optimization of existing solar cell technologies for greater efficiency. In any case, bifacial panels still lead to the loss of space since much of the space around and above them cannot be used afterwards.
Solar farms, whether they are adaptable for agrivoltaics or not, have been proven to be highly controversial especially at community level. The issue of loss of arable land that can be used for agriculture still commands strong political attention.
The solar industry is not only driven by market movers and capitalist interests, but also by green energy advocacy, energy politics and activism. In those quarters, agrivoltaics is touted as a sort of cure-all solution with the more practical issues taking the backseat. Regardless, while not yet an object of major public interest, agrivoltaics has proven benefits though these benefits have been seen mainly with shade-tolerant crops like lettuce, spinach, potatoes and tomatoes. The amount of experience with agrivoltaics is fairly limited. However, it is without doubt that the experience is valuable as it continues to expand the body of useful knowledge gained from experimentation with agrivoltaics. It will be nice to see what the future holds.
Meanwhile, Solarkobo helps homeowners and businesses in Lagos and throughout Nigeria, including agricultural business owners make the best choice of solar panels, inverter and charge controllers that fits their budget and meets their power needs.