Source: NCSU COOPERATIVE EXTENSION

Once farmland has been converted to solar energy production, many factors should be considered prior to converting the land back to agricultural use. This includes the cost of decommissioning, disposal, or recycling of equipment, restoration of soil fertility, checking for heavy metal levels that might limit plant growth, and checking soil for hardpans. The assumption that land in solar production can easily be converted back to farmland use is not always valid.

DECOMMISSIONING COSTS
First, consider the cost associated decommissioning. A study by NC Department of Environmental Quality shows that within North Carolina, there are currently more  than 600 wind or solar energy production sites. Approximately 40% of these are solar production sites between 25-50 acres containing up to 250,000 solar panels per site. Collectively, these panels weigh a bit over 500,000 tons that will need to be transported, recycled or disposed. Regrettably, at the moment, disposal is the only feasible options. Perhaps in years to come this market will emerge as a viable option. Until then, cost of disposal into landfills, transportation, and associated effort will result in decommissioning cost of about $30,000 per Megawatt (MW). Within North Carolina, this equates to about $750,000-$1.5 million per site. Furthermore, ruling as to whether the battery components will be considered hazardous waste  is yet to be determined. Currently, disposal guidance for batteries is found within Spent Lead Acid Battery Management. While the battery components are still in question, lead, selenium, copper, arsenic, silver and cadmium compounds are known to exists within solar panels. These are considered hazardous waste and will need special care for disposal.

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