Sacrificial Anodes that are used for Solar Panel Farms typically would be soil anodes that would be designed to protect the buried galvanized steel piles that support the arrays
Packaged zinc or magnesium anodes are usually used depending on soil chemistry.
It is important to consider the impact of Copper Ground Rod systems, as they can have a greater influence on corrosion than the actual soil conditions.
The anodes would be designed for life extension of the structural supporting galvanized piles
Further information for magnesium soil anodes can be found by clicking on the link below
Galvotec packaged Magnesium soil anodes
Zinc Soil Anodes are used where soil conditions require the use of Zinc Anodes such as saline mud below 120 F (50 C). These anodes would protect objects underground such as storage tanks, containers, buried structures, and the galvanized piles used in the support structures of the solar farm arrays
Further information on zinc soil anodes can be found on page 10 in the link below
http://www.galvotec.com/catalogs/Zinc/