Adoption of Agrisolar Technologies in Hawai’i

Ridge to Reefs staff, including Emma Verlinden, Phal Mantha, and Paul Sturm

Hawai’i has a deep-rooted agricultural history, and today there are more than 7,000 individual farms in operation. Due to a confluence of factors, agricultural producers in Hawai’i face a variety of significant challenges when compared with their mainland counterparts. High costs associated with land, labor, and inputs, as well as relative geographic isolation from large markets in the continental United States are notable contributing factors. Other challenges in the form of habitat modifying invasive species, degraded agricultural infrastructure, and legacy agricultural problems continue to impact the agricultural viability and competitiveness of Hawaiian producers today. Furthermore, electricity costs in the Hawai’i are among the highest in the United States with residential consumers paying an average of about 37 cents a kilowatt-hour (UH-HERO ). In 2015, the State of Hawai’i mandated that by the year 2045, 100% of the state’s electricity must be generated by renewable energy sources. Electric companies on the islands have made efforts to increase their renewable energy portfolio, such as energy provider Hawaiian Electric, which increased its renewable sources to 38.4% in the past few years. Though a variety of challenges exist, widespread adoption of regionally adapted agrisolar models could provide Hawaiian agricultural producers, landholders, and communities with significant benefits. A closer look at recent solar developments and related progress (or lack of progress in some cases) in Hawaii may help to paint a clearer picture of the opportunities and challenges that are associated with adoption of these technologies.

The Wailua Egg Solar + Sheep Farm is a 6 MW Solar + battery project that will host 1 million cage free chickens spread across 11 buildings and raise 200 sheep a year for Oahu markets and restaurants. The facility is completely grid independent with solar arrays incorporated into cage free shelters and the resulting poultry litter being converted into biochar by gasifiers. Wastewater and process water are recycled for irrigation purposes and are also land applied to designated leach fields located on site.

Figure 1: Aerial image of Wailua Egg Solar Sheep Farm’s existing solar poultry houses. The proposed expansion of this solar farm and sheep grazing operations have faced some local opposition due to a variety of concerns.

Figure 2: Aerial view of the farm’s poultry litter gasifier, which converts poultry litter into biochar, a valuable soil amendment.

Figure 2: Aerial view of the farm’s poultry litter gasifier, which converts poultry litter into biochar, a valuable soil amendment.

Though there are clear cost, food security, and environmental benefits associated with this operation, concerns have been raised about upcoming expansions (specifically, the proposed solar farm and sheep grazing areas). In Hawai’i, IAL (Important Agricultural Lands) designation prohibits all uses except what is defined as “agricultural use.” This has the potential to limit the locations where photovoltaic and agrisolar projects can be developed. This criticism also serves to highlight a key issue surrounding these projects in the state: the “food vs. Fuel” debate and the use of prime agricultural lands for energy generation. This is one reason this project has run into local opposition, with some citizens and residents reporting that they are concerned over the use of fallow “prime agricultural lands” for power generation. Though these are valid concerns, integrating grazing practices and other forms of agriculture with photovoltaic based power generation may help to balance these concerns and simultaneously produce power and food on the lands. According to a recent white paper published by the Ulupono Initiative citing University of Hawai’i researcher Dr. Matthias Fripp’s work, a viable solution may be to utilize sloped lands for these developments so that they do not use up prime agricultural lands. Specifically, this publication notes that “While solar developers may be apprehensive to developing on higher-sloped lands…a willingness to develop solar facilities on sites with <20% slope, at a slightly higher per project cost, will allow for most, if not all, of Oahu’s agricultural lands to be protected.”

Other challenges to solar developments in the state include the Jones Act, which can limit procurement options, resulting in high material and shipping costs. Furthermore, Land Study Bureau Classifications classifying farmland from most productive to least productive can limit areas that can be used for such projects. Though challenges to widespread adoption of agrisolar technologies in Hawai’i still exist, there is strong potential for numerous co-benefits both at the utility and individual farm scale.

Figure 3: Integrating grazing sheep with solar developments in the Hawai’i has proven to be an effective and low cost solution to managing agressive invasive grasses such as Guinea Grass and Cane Grass which can be the dominant land cover on many agricultural lands in the state.

Even at the individual farm scale, integration of photovoltaics with agricultural operations can facilitate a diverse array of use cases and has the potential to yield numerous benefits for local stakeholders. For example, photovoltaics integrated with refrigeration systems can provide robust, grid-independent cold storage and energy for critical operations and post-harvest processing facilities.

Figure 4: Th is breadfruit farm, nursery, and value-added product manufacturing facility for breadfruit flour in Puerto Rico is powered entirely by solar power. This model can also be applied in Hawa’ii and has the potential to provide farmers with robust grid independent post-harvest processing capabilites.

Furthermore, solar irrigation, water filtration, native species, and pollinator habitat can all be integrated with these solutions in a regionally adapted and relevant manner. Specifically, adoption of agrisolar technologies can provide agricultural practitioners with the opportunity to generate additional income, reduce operational and maintenance costs, decrease water consumption, utilize marginal agricultural lands, and protect the quality of their soil. Financially, these solutions may allow them to generate additional income by selling electricity from their lands, leasing land to solar developers, and powering their own farm equipment. The cost of imported energy sources, such as petroleum and coal, to Hawai’i is approximately – three to four times higher than on the mainland and decreasing the need for these sources by constructing solar modules on agricultural land could save farmers a great deal.

In fact, a study in 2012 showed that the standard solar construction in Hawai’i paid for itself in only four years and generated a profit of over four times the initial cost over the course of its life (8 ). Farmers can also decrease the cost of irrigation on their lands. There are currently solar modules that are being used to fully power irrigation systems on farmland in Africa, South America, and India (1). The significance of this is great, as roughly 85% of all water use globally is for irrigation systems, and Hawai’i is actively experiencing difficulty with water shortages and seeking innovative solutions for increasing water availability and reuse. Plants and crops that are grown underneath the shade of solar panels require less water than when exposed to full sunlight. This is due to the fact that plants in full sunlight reach their light saturation point earlier in the day, after which they do not grow more or photosynthesize more, they simply require even greater amounts of water to process the levels of sunlight.

Hawai’i also has an extensive history of monocultural plantation agriculture that has left a lasting mark on the quality of the soil where farmers are growing crops today, exemplifying what are known as legacy agricultural issues. In some areas, nutrients and organic matter from the soil have been heavily overdrawn, forcing farmers to rely on expensive imported fertilizers to maintain their production. Over the course of these decades, excessive tilling of the earth and subsequent depletion of organic matter has led to erosion, soil loss, and pollution to sensitive coastal ecosystems. There are also previously used agricultural roads that often are no longer actively managed, which combined with erosion are leading to ongoing pollution and sediment export from these areas. One study found that solar installations can provide a recovery period for overused soil and actually increase the value of agricultural land over time by revitalizing soil over the course of the panels’ 20- to 25-year life.

Another issue facing agricultural producers in Hawai’i is the undulating topography of the islands that makes much of their land unusable for general agricultural practices. By relegating areas of steep topography for solar panel installation, farmers can increase the amount of usable space on their farms. When combined with grazing animals such as sheep, the productivity of these panels is increased, and the costs of maintenance for the panels is greatly reduced. An analysis of maintenance costs by Nexamp showed that solar grazing saved the company 19% on flat ground, but where panels were built on steep ledges and grazed under, they saved 38% (2). Another benefit to agricultural land use in the state of Hawai’i that could benefit from agrisolar practices would allow farmers to make use of dry, arid lands, such as those seen on windward slopes of the islands or the Kaupo region of Maui. Dr. Barron-Gifford at the University of Arizona found that dry land crops yielded substantially greater production when grown under solar panels: Chiltepin pepper plants yielded three times as much fruit, tomatoes two times as much, and all were seen to require less water than without panel coverage (3). Therefore, combining dryland agriculture with novel agrisolar solutions may prove to have numerous advantages over using either one of these strategies on their own.

Benefits such as these could significantly increase agricultural productivity throughout the Hawai’ian Islands, creating a more sustainable agricultural economy and giving local families a greater opportunity to save money and to access locally grown foods. There are many government programs now that can assist farmers in making the transition from general agriculture to agrisolar, and with the pressing need for sustainability, this may present as one of the most important solutions for Hawai’i’s ongoing economic and environmental difficulties.

1. 2020 Guide to Hawaii Solar Panels I Incentives, Rebates, and Tax Credits
2. Lynn Freehill-Maye, 2020, A New Vision for Farming: Chickens, Sheep, and … Solar Panels, Christian Science Monitor,
3. ASGA, 2020, Utility Dive Does a Deep Dive on Solar Grazing,
4. Solar Energy Technologies Office, Farmer’s Guide to Going Solar, Depoartment of Energy,
5. Sustainable Farm Agrivoltaic, Oregon State University,
6. Dr. Matthias Fripp, 2022, White Paper: Switching the paradigm, Ulupono Initiative,
7. Taylor Freitas, 2022, Hawaii Solar Panels: Pricing and Incentives, Save On Energy,
8. Solar Power in Hawaii, Wikipedia,
9. Thomas Heaton, 2022, Hawaii Needs Good Soil To Grow More Food. Here’s How That Can Happen, Honolulu Civil Beat,
10. Maui News, 2022, Hawaii Electric hits 38% renewable energy in 2021; Maui County at 50%,
11. USDA, 2017, Census of Agriculture State Profile,