This document describes a proposed solar powered irrigation system for a smallholder farm in Colombia. The farm is located in Paipa at an altitude of 2526 meters above sea level and grows crops like oats, barley, wheat, corn, potatoes, and fruits. The irrigation system will draw water from a nearby perennial stream and pump it to an overhead water tank located 6 meters above the stream and 4.5 meters above a small greenhouse. Given the pumping head of 2040 meters and a daily water demand of 0.2 cubic meters, about 28.3 kW of photovoltaic panels would be needed to power the system.

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LEADERSHIP TRACK UNIT 01 2014 04 14 2
Low-cost solutions for smallholder
agriculture
Gonzalo Pradilla; Sarah Edelman; Michael Lopez; Innocent
Azih.
Chapter 1: Case study location
The proposed solar powered irrigation system will be located in the following area:
Continent South America
Country Colombia
Region The farm is located in the Colombian Andes, in the Boyacá Department, 180
km north of the capital Bogotá, at an altitude of 2526 meters above sea
level. The municipality´s name is Paipa.
Coordinates 5°44’22.48” N 73°07’05.16” W
Short description
about the socio
economy of the
region (max. 500
words)
Paipa is located in the valley of Sogamoso in central eastern Colombia.
Paipa is at a height of 2525 meters above sea level. It has an average
temperature of 13°C. The average rainfall ranges from 500 mm/year in the
flat area of the Valley of Tundama and 3000 mm/year in the mountainous
area. The multi-year average relative humidity is 81%, with values ranging
from 78% (February) and 83% (May). The average annual solar brightness
is 1300 hours/year. The average potential evapotranspiration annual (ETo)
is in a range of values between 1000 and 1200 mm/year. At stations located
in Paipa occur annual rainfall of 1145.7 mm/year and (ETo) of 1076.4
mm/year generating conditions of excess water average of 69.3 mm/year. In
Paipa rainfall regime is characterized by conditions of water deficiency in
the month of January, as well as in the period from July to August.
The watersheds that make up the municipality of Paipa are: Chicamocha
river basin comprised 17,825 ha, Palermo river basin with 9,560 ha, and
Tolotá river basin comprised 4.445 ha.
The products generated by the rural farming in Paipa are: oats, barley,
wheat, corn, potatoes, vegetables (in family vegetables gardens), milk and
meat, fruit (apples, tree tomatoes, moron, passion fruit, peaches). In
addition, there are coal, sand and stone mineral exploitation, which are kept
on a small-scale.
With regard to the marketing of these products, 80% are sold in some
marketplaces located in Paipa, and the other 20% in other municipalities like
Duitama and Tunja. 100% of milk and meat production is for local
consumption. Only a fraction of these products are intended for home
consumption.
Around 69% of producers do not receive technical assistance. 35% of
farmers have irrigation system for their farm activities; of these, 40% use
sprinkler irrigation, 35% gravity-assisted irrigation, 10% micro-irrigation and
15% drop irrigation. All producers have conventional electricity on their
farms.
The municipality of Paipa is located in a mountainous area with slopes
ranging between 0 and 75%. Establishing crops may have environmental
and economic effects of importance. The larger the angle and length of the

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LEADERSHIP TRACK UNIT 01 2014 04 14 3slope, the greater the risk to erosion associated with the speed and volume
of runoff. This feature also makes it difficult for mechanization and technical
management of crops. Under these conditions, an integrated approach to
managing the production systems and alternative technological measures
are required.
Optional
Chapter 2: Farming system and water requirement
Farming system 1. The selected site is an agroecological -and therefore diversified- farming
system, where there are more than 70 different species and cultivars
simultaneously cultivated, with onion (Allium cepa), lettuce (Lactuca sativa),
cauliflower (Brassica oleracea var. botrytis) broccoli (Brassica oleracea),
maize (Zea mays) and quinoa (Chenopodium quinoa) being the most
important crops.
Recently, a small communitarian greenhouse (72m2) has been built by a
local rural women’s organization, which is meant to produce vegetable
seedlings for other farms, as well as some crops that require special
temperature and humidity conditions such as tomatoes (Solanum
lypersicum). However, the greenhouse has no irrigation system, so this first
assignment will consist on designing a proper one according to local
conditions.
Water
requirement
(maximum 1000
1. Existing irrigation systems and water availability for irrigation per month
(m3/month):

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LEADERSHIP TRACK UNIT 01 2014 04 14 4words) There is a perennial stream on the margin of the farm, which would be the
main water source for the irrigation system. Its mean water flow rate is
approximately 15 l/s (0.015 m3/s). Please provide information on the existing
irrigation systems (water availability for irrigation purpose, e.g. ideally per
day (m3/day), or per month (m3/month) if daily data is not available).
Water demand per month for the tomatoes was calculated using CropWat ,
but we were not able to calculate the total water demand for all crops
together (1/5 of the greenhouse is devoted to seedlings production, the rest
to tomato) with this date. Therefore, it was calculated using an average
water requirement reported in literature for each plant of 1,5 l per day.
Approximate cropping area: 72m2
Approximate water requirements per day: 0.2 m3 / 2,000 l
Figure 3: Schematic representation of the Greenhouse: seedling trays (left)
and crops (right).

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LEADERSHIP TRACK UNIT 01 2014 04 14 5Chapter 3: Pumping head (height) calculation
Pumping head The farm is located over a hill (Figure 2). The stream is at the lowest point,
and the greenhouse was built up the hill (about 6 mts vertical from the
stream), so we must add this height to the height difference between the
tank and the greenhouse level.
The height of the water storage from the highest irrigation point (seedlings
trays 1 m above ground) is about 1,9 m, which is enough for a drip/trickle
irrigation system (1-2 m).
Taking this into account, the best irrigation scheme would be drip, to
minimize the increase in the water head.
Table 1: Pumping head calculation
Chapter 4: Sizing of the SPIS
PV panel size
(capacity)
Figure 3: Schematic representation of the Greenhouse: seedling trays (left)
and crops (right).
Ppeak = 8.0*Ht*Vday / Gtotal,day
Vday = Daily crop water requirement (m3/day)
HT = Total pumping head (m)
Gtotal,day = Mean daily global solar radiation for the design month
(kWh/m2.day)

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LEADERSHIP TRACK UNIT 01 2014 04 14 6Ppeak = Solar panel power (Wp)
Vday=0.2 m3
HT=2040m
Gtotal,day=115.43
Ppeak=28.28
According to the local conditions described above, there is a global
irradiation of 115.43 kWh/m²day. It takes approximately 28.3 kWp PV
generator to deliver from the stream up to the water tank over the hill, to
supply water at the rate of 0,2 m³/d (at a head of 2040 m).
Chapter 5: Summary
PV panel size
(capacity)
In summary
This analysis was carried on a project in Colombian farmland that is good
for tubers and vegetables farming. The irrigated scheme used is the trickle
technology for a greenhouse scheme on a hill in which water was drawn
from a low-lying river and fed into an overhead tank. The use application of
gravitational pull for water to trickle from the higher player water tank to the
greenhouse, 4.5 meters below the tank and lying 6 meters above the
waterbed ensures that water trickle height was 1,9m down to crops in the
greenhouse. The trickle method applied was a quick and cheaper and
efficient scheme for this kind of project
This work also calculated the PV size for pumping water using the solar PV
system, to the water tank using a 23m pipe up the gradient 10.5 meters
above the stream, a scheme that will generate approximately 28.3 kWp PV
power for that purpose at a supply water rate of 0,2 m³/d (at a head of 2040
m above the stream). This way a renewable energy scheme is employed to
power agriculture even at the smallholder level.