The purpose of this report is to describe the results of a study
on the economic feasibility of using photovoltaic arrays to power irri-
gation systems in Florida. For this analysis a photovoltaic system is
assumed to be economically feasible if the discounted cost of such a
system over a given period of time is less than the corresponding dis-
counted cost of currently used conventional systems. Following Matlin
and Katzman [1978], the initial year in which photovoltaic ,co" will
be economically feasible is determined under a variety of economic and
institutional assumptions.
 The use of photovoltaic arrays for powering irrigation systems
represents a substantial change in the structure of irrigation energy
costs. The cost structure of powering irrigation systems with currently
used conventional fuels (e.g., electricity, diesel fuel, etc.) is one
that entails a moderate fixed cost in the pump-power unit, but rather
substantial variable fuel costs [Harrison, 1976]. Conversely, the cost
structure of irrigation systems powered by photovoltaic arrays is
characterized by a substantial fixed cost in the pump power-unit, but
very low (possibly negative) variable energy costs. This difference in
energy cost structure is significant in that farmers using photovoltaic
arrays reduce the direct impact of rising conventional fuel prices on
irrigation energy costs.
 While such a shift in the composition of irrigation energy costs
may be desirable, the high fixed cost of photovoltaic systems is currently
prohibitive. At present, photovoltaic system costs are approximately
$10.75 per peak watt [Litka et al., 1981]. Thus, the fixed investment
cost of an array of sufficient size to power an irrigation system would
not be justified economically. System costs, however, are expected to
decline substantially as commercial production of these systems proceeds
[Smith, 1981].
 The key factors in determining the economic feasibility of powering
 irrigation systems with photovoltaic arrays are the cost of these systems,
 the rate at which conventional energy prices increase and the rates
 2
 utilities pay for electricity purchased from dispersed energy systems.

 2Dispersed energy systems denote systems which produce energy, in
 this case electricity, at the site of use. Under Federal Energy