Difference between revisions of "Design of Photovoltaic (PV) Pumping"

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'''Introduction'''
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= Overview<br/> =
  
−
In order to implement cost effective photovoltaic (PV) pumping system, it is necessary to follow some basic guidelines to design and size every system component. This page will explain about detailed calculation needed for sizing every system component. The basic step to design photovoltaic (PV) pumping system is:
+
In order to implement cost effective '''photovoltaic (PV''') pumping system, it is necessary to follow some basic guidelines to design and size every system component. This page will explain about detailed calculation needed for sizing every system component.
  
−
1. Determination of water supply need
+
<u>The basic step to design photovoltaic (PV) pumping system is:</u>
  
−
2. Calculation of pumping head
+
#[[Design_of_Photovoltaic_(PV)_Pumping#Determination_of_Water_Supply_Need|Determination of water supply need]]
 +
#[[Design_of_Photovoltaic_(PV)_Pumping#Calculation_of_Pumping_Head|Calculation of pumping head]]
 +
#[[Design_of_Photovoltaic_(PV)_Pumping#Estimation_of_Solar_Resource|Estimation of solar resource]]
 +
#[https://energypedia.info/index.php/Design_of_Photovoltaic_(PV)_Pumping#Finding_Appropriate_Solar_Pump_and_Inverter Finding appropriate solar pump and inverter]
 +
#[https://energypedia.info/index.php/Design_of_Photovoltaic_(PV)_Pumping#Calculation_of_PV_Panel_Required Calculation of PV panel required]
  
−
3. Estimation of solar resource
+
<br/>
  
−
4. Finding appropriate solar pump and inverter
+
= Determination of Water Supply Need<br/> =
  
−
5. Calculation of PV panel required
+
<u>There are two distinct application for photovoltaic (PV) pumping system<ref name="Photovoltaic Pumping Overview">https://energypedia.info/index.php/Photovoltaic_(PV)_Pumping</ref>:</u>
  
 +
#Drinking water supply (domestic water supply)
 +
#Irrigation water supply
  
 +
<br/>
  
−
'''Determination of Water Supply Need'''
+
== Domestic Water Supply<br/> ==
  
−
According to&nbsp;<ref name="Photovoltaic Pumping Overview">https://energypedia.info/index.php/Photovoltaic_(PV)_Pumping</ref>, there are two distinct application for photovoltaic (PV) pumping system;&nbsp;
+
For domestic water supply, the first data needed is to estimate the water requirement for one person/day.
  
−
1. Drinking water supply (domestic water supply)
+
A good estimate can be found in "[http://pacinst.org/wp-content/uploads/2012/10/basic_water_requirements-1996.pdf Basic Water Requirements for Human Activities: Meeting Basic Needs]" , that relate how much water required to sustain particular activities. <u>Here is the estimate</u><u><ref name="Basic Water Needs for Human Activities">http://www.pacinst.org/reports/basic_water_needs/basic_water_needs.pdf</ref></u><u>:</u>
  
−
2. Irrigation water supply
+
{| cellspacing="1" cellpadding="1" border="1" style="width: 100%"
 +
|-
 +
|
 +
{| cellspacing="1" cellpadding="1" border="1" style="width: 297px"
 +
|-
 +
| style="background-color: rgb(204, 204, 204)" |
 +
'''Purpose'''
  
 +
| style="background-color: rgb(204, 204, 204)" | <p style="text-align: center">'''Recommended minimum'''</p><p style="text-align: center">'''(liter/person/day)'''</p>
 +
<br/>
  
 +
|-
 +
|
 +
Drinking water
  
−
'''Determination of Water Supply Need (domestic water supply)'''
+
| <p style="text-align: center">5</p>
 +
|-
 +
|
 +
Sanitary services
  
−
<br/>For domestic water supply, the first data needed is to estimate the water requirement for one person/day. A good estimate can be found from&nbsp;<ref name="Basic Water Needs for Human Activities">http://www.pacinst.org/reports/basic_water_needs/basic_water_needs.pdf</ref>, that relate how much water required to sustain particular activities. Here is the estimate:
+
| <p style="text-align: center">20</p>
 +
|-
 +
|
 +
Bathing
  
−
Purpose &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Recommended minimum (liter/person/day)
+
| <p style="text-align: center">15</p>
 +
|-
 +
|
 +
Cooking and Kitchen
  
−
Drinking water &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;5&nbsp;
+
| <p style="text-align: center">10</p>
 +
|-
 +
| style="background-color: rgb(204, 204, 204)" |
 +
'''Total'''
  
−
Sanitary services &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;20
+
| style="background-color: rgb(204, 204, 204)" | <p style="text-align: center">'''50'''</p>
 +
|}
  
−
Bathing &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;15
+
|
 +
<u>For example:</u>
  
−
Cooking and Kitchen &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 10
+
*if there are a village with basic need of drinking water, bathing and sanitary services but no need for cooking; then it will require 5+20+15=40 liter/person/day.
 +
*If the population is 300 persons, then the entire village will require 300 x 40 = 12 000 liter/day.
 +
*Normally to compensate for water leakage on piping or distribution, 20% additional water will be required then the village will require 14 400 liter/day or 14.4 m3/day.
  
−
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; _______+
+
|}
  
−
Total &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 50
+
<br/>
  
 +
== Irrigation Water Supply ==
  
 +
= Calculation of Pumping Head<br/> =
  
−
For example, if there are a village with basic need of drinking water, bathing and sanitary services but no need for cooking; then it will require 5+20+15=40 liter/person/day. If the population is 300 persons, then the entire village will require 300 x 40 = 12 000 liter/day. Normally to compensate for water leakage on piping or distribution, 20% additional water will be required then the village will require 14 400 liter/day or 14.4 m3/day.&nbsp;
+
Pumping head is normally measured in meter (m), so sometimes there are misconception that pumping head is equal to pumping elevation. In actual, pumping head is divided into three components: elevation head, major losses head, and minor losses head.
 +
 
 +
Pumping Head (m) = Elevation Head (m) + Major Losses Head (m) + Minor Losses Head (m)
 +
 
 +
#Elevation head is measured from the water source surface level to the point of outlet pipe level.
 +
#Major losses head is influenced by water flow rate, diameter of pipe, length of pipe, and type of pipe (PVC, HDPE etc)
 +
#Minor losses head is influenced by piping accessories including valve, elbow, inlet pipe etc
 +
 
 +
The detailed explanation can be found on "[http://www.raeng.org.uk/education/diploma/maths/pdf/exemplars_advanced/17_pumping_water.pdf The Mathematics of Pumping Water, AECOM Design Build Civil, Mechanical Engineering"].
 +
 
 +
<br/>
 +
 
 +
= Estimation of Solar Resource<br/> =
 +
 
 +
Ideally, a ground based solar radiation measurement in location to be installed with solar water pumping system, is required in order to measure accurately the solar resource available for every part of the year. However, due to expensive equipment required, alternative data can be obtained from [http://eosweb.larc.nasa.gov/sse/ "Surface meteorology and Solar Energy" (NASA)] for every part of the world freely or other solar resource data website available in the internet.
 +
 
 +
Solar resources available per day is cited on unit of kWh/m2/day or PSH (peak sun hour) with 1 kWh/m2/day = 1 PSH. Common confusion of solar resource data understanding is usually with solar data cited on unit of W/m2 that describe power.
 +
 
 +
<u>What is needed on solar pumping design is data cited on energy:</u>
 +
 
 +
#Solar Energy / Day ► cited on unit of kWh/m2/day or PSH (commonly used for solar pumping design)
 +
#Instantaneous Solar Power ► cited on unit of W/m2 (only used for complex modelling)
 +
 
 +
<br/>
 +
 
 +
 
 +
= Finding Appropriate Solar Pump and Inverter =
 +
 
 +
The most important criteria on determining the optimum solar pump is by finding the pump that can satisfy both of daily water flow and pumping head requirement. Normally a solar pump can operate on wide range of water flow rate in response to variation of solar radiation.
 +
 
 +
<u>Generally there are three kinds of pump normally used as solar pump:</u>
 +
 
 +
#Centrifugal pump
 +
#Helical rotor pump
 +
#Piston (diapraghm) pump
 +
 
 +
<br/>
 +
 
 +
<u>Here is the table that explain the different characteristic of solar pump</u> <ref name="Solar Water Pumps in Namibia">http://www.drfn.info/docs/cbend/energy_factsheets/solar_water_pumps.pdf</ref>:
 +
 
 +
{| cellspacing="1" cellpadding="1" border="1" style="width: 100%"
 +
|-
 +
| style="background-color: rgb(204, 204, 204)" |
 +
Type
 +
 
 +
| style="background-color: rgb(204, 204, 204)" |
 +
Pumping Head (m)
 +
 
 +
| style="background-color: rgb(204, 204, 204)" |
 +
Flow Rate (m3/day)
 +
 
 +
| style="background-color: rgb(204, 204, 204)" |
 +
Mechanism
 +
 
 +
|-
 +
|
 +
Centrifugal pump
  
 +
<br/>
  
 +
| <p style="text-align: center">0 to 80</p>
 +
| <p style="text-align: center">6 to 20</p>
 +
|
 +
Similar to conventional pump
  
−
'''Calculation of Pumping Head'''
+
|-
 +
|
 +
Helical rotor pump
  
−
Pumping head is normally measured in meter (m), so sometimes there are misconception that pumping head is equal to pumping elevation. In actual, pumping head is divided into three components: elevation head, major losses head, and minor losses head.
+
<br/>
 +
 
 +
| <p style="text-align: center">50 to 150</p>
 +
| <p style="text-align: center">> 20</p>
 +
|
 +
Robust, only one turning part
 +
 
 +
|-
 +
|
 +
Piston (diaphragm) pump
  
−
Pumping Head (m) = Elevation Head (m) + Major Losses Head (m) + Minor Losses Head (m)
+
<br/>
  
−
1. Elevation head is measured from the water source surface level to the point of outlet pipe level.
+
| <p style="text-align: center">0 to 150</p>
 +
| <p style="text-align: center">2 to 5</p>
 +
|
 +
Complex, lot of moving parts, require oil lubrication
  
−
2. Major losses head is influenced by water flow rate, diameter of pipe, length of pipe, and type of pipe (PVC, HDPE etc)
+
|}
  
−
3. Minor losses head is influenced by piping accessories including valve, elbow, inlet pipe etc
+
<br/>
  
−
The detailed explanation can be found on&nbsp;<ref name="Mathematic of Pumping Water">http://www.raeng.org.uk/education/diploma/maths/pdf/exemplars_advanced/17_pumping_water.pdf</ref>.
+
For simplicity of design and maintenance, it is suggested that the inverter should come from one package (one supplier) with the solar pump. This will prevent operating mismatch and guarantee easier troubleshooting.
  
 +
For pumping head, it is always imperative to keep the pump head specification higher than the required pumping head. A safety factor of 30% might be needed if the water level condition is not stable. If the pump cannot fulfill the pumping head requirement, no matter how bright the sunlight is, it will not provide any water at all.
  
 +
For water flow required, some solar pump supplier usually provide a sizing chart that will help user to predict how much solar power required to provide for daily flow requirement. In order to use this sizing chart, user need data from previous step to determine how much solar resource available per day in terms of kWh/m2/day or PSH. This will in turn decide how much solar power you require for the solar pump. Unlike the pumping head requirement, if the pump water flow capacity is lower (due to specification or cloudy day), it still capable to provide water eventhough the sun is not as bright (it will only provide less quantity of water).
  
−
'''Estimation of Solar Resource'''
+
<br/>
  
−
Ideally, a ground based solar radiation measurement in location to be installed with solar water pumping system, is required in order to measure accurately the solar resource available for every part of the year. However, due to expensive equipment required, alternative data can be obtained from&nbsp;[http://eosweb.larc.nasa.gov/sse/ http://eosweb.larc.nasa.gov/sse/]&nbsp;for every part of the world freely or other solar resource data website available in the internet.&nbsp;
 
  
−
Solar resources available per day is cited on unit of kWh/m2/day or PSH (peak sun hour) with 1 kWh/m2/day = 1 PSH. Common confusion of solar resource data understanding is usually with solar data cited on unit of W/m2 that describe power. What is needed on solar pumping design is data cited on energy.
+
= Calculation of PV Panel Required =
  
−
1. Solar Energy / Day --> cited on unit of kWh/m2/day or PSH &nbsp; &nbsp; (commonly used for solar pumping design)
+
The calculation of PV panel number required should be based on the specification of the solar pump inverter input. Normally they will suggest a range of DC Input Voltage and inverter power required. The number of PV panel required is related to the specification of individual panel. The common misconception is that you can estimate based on the number of panel (they had different capacity) or size (it might had different efficiency).
  
−
2. Instantaneous Solar Power --> cited on unit of W/m2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (only used for complex modelling)
+
<br/>
  
 +
= Further Information<br/> =
  
 +
*[[Photovoltaic_(PV)_Pumping|Photovoltaic (PV) Pumping]]
 +
*[http://www.raeng.org.uk/education/diploma/maths/pdf/exemplars_advanced/17_pumping_water.pdf The Mathematics of Pumping Water, AECOM Design Build Civil, Mechanical Engineering]
 +
*[http://www.pacinst.org/reports/basic_water_needs/basic_water_needs.pdf Basic Water Requirements for Human Activities: Meeting Basic Needs]
 +
*[[Toolbox on SPIS|Toolbox on Solar Powered Irrigation Systems]]
 +
<br/>
  
−
'''References'''
+
= References<br/> =
  
 
<references />
 
<references />
Line 83: Line 201:
 
[[Category:Pumping]]
 
[[Category:Pumping]]
 
[[Category:Solar]]
 
[[Category:Solar]]
 +
[[Category:Photovoltaic_(PV)]]
 +
[[Category:Solar_Pumping]]
 
[[Category:Water_Supply]]
 
[[Category:Water_Supply]]

Latest revision as of 13:00, 29 May 2018

Overview

In order to implement cost effective photovoltaic (PV) pumping system, it is necessary to follow some basic guidelines to design and size every system component. This page will explain about detailed calculation needed for sizing every system component.

The basic step to design photovoltaic (PV) pumping system is:

  1. Determination of water supply need
  2. Calculation of pumping head
  3. Estimation of solar resource
  4. Finding appropriate solar pump and inverter
  5. Calculation of PV panel required


Determination of Water Supply Need

There are two distinct application for photovoltaic (PV) pumping system[1]:

  1. Drinking water supply (domestic water supply)
  2. Irrigation water supply


Domestic Water Supply

For domestic water supply, the first data needed is to estimate the water requirement for one person/day.

A good estimate can be found in "Basic Water Requirements for Human Activities: Meeting Basic Needs" , that relate how much water required to sustain particular activities. Here is the estimate[2]:

Purpose

Recommended minimum

(liter/person/day)


Drinking water

5

Sanitary services

20

Bathing

15

Cooking and Kitchen

10

Total

50

For example:

  • if there are a village with basic need of drinking water, bathing and sanitary services but no need for cooking; then it will require 5+20+15=40 liter/person/day.
  • If the population is 300 persons, then the entire village will require 300 x 40 = 12 000 liter/day.
  • Normally to compensate for water leakage on piping or distribution, 20% additional water will be required then the village will require 14 400 liter/day or 14.4 m3/day.


Irrigation Water Supply

Calculation of Pumping Head

Pumping head is normally measured in meter (m), so sometimes there are misconception that pumping head is equal to pumping elevation. In actual, pumping head is divided into three components: elevation head, major losses head, and minor losses head.

Pumping Head (m) = Elevation Head (m) + Major Losses Head (m) + Minor Losses Head (m)

  1. Elevation head is measured from the water source surface level to the point of outlet pipe level.
  2. Major losses head is influenced by water flow rate, diameter of pipe, length of pipe, and type of pipe (PVC, HDPE etc)
  3. Minor losses head is influenced by piping accessories including valve, elbow, inlet pipe etc

The detailed explanation can be found on "The Mathematics of Pumping Water, AECOM Design Build Civil, Mechanical Engineering".


Estimation of Solar Resource

Ideally, a ground based solar radiation measurement in location to be installed with solar water pumping system, is required in order to measure accurately the solar resource available for every part of the year. However, due to expensive equipment required, alternative data can be obtained from "Surface meteorology and Solar Energy" (NASA) for every part of the world freely or other solar resource data website available in the internet.

Solar resources available per day is cited on unit of kWh/m2/day or PSH (peak sun hour) with 1 kWh/m2/day = 1 PSH. Common confusion of solar resource data understanding is usually with solar data cited on unit of W/m2 that describe power.

What is needed on solar pumping design is data cited on energy:

  1. Solar Energy / Day ► cited on unit of kWh/m2/day or PSH (commonly used for solar pumping design)
  2. Instantaneous Solar Power ► cited on unit of W/m2 (only used for complex modelling)



Finding Appropriate Solar Pump and Inverter

The most important criteria on determining the optimum solar pump is by finding the pump that can satisfy both of daily water flow and pumping head requirement. Normally a solar pump can operate on wide range of water flow rate in response to variation of solar radiation.

Generally there are three kinds of pump normally used as solar pump:

  1. Centrifugal pump
  2. Helical rotor pump
  3. Piston (diapraghm) pump


Here is the table that explain the different characteristic of solar pump [3]:

Type

Pumping Head (m)

Flow Rate (m3/day)

Mechanism

Centrifugal pump


0 to 80

6 to 20

Similar to conventional pump

Helical rotor pump


50 to 150

> 20

Robust, only one turning part

Piston (diaphragm) pump


0 to 150

2 to 5

Complex, lot of moving parts, require oil lubrication


For simplicity of design and maintenance, it is suggested that the inverter should come from one package (one supplier) with the solar pump. This will prevent operating mismatch and guarantee easier troubleshooting.

For pumping head, it is always imperative to keep the pump head specification higher than the required pumping head. A safety factor of 30% might be needed if the water level condition is not stable. If the pump cannot fulfill the pumping head requirement, no matter how bright the sunlight is, it will not provide any water at all.

For water flow required, some solar pump supplier usually provide a sizing chart that will help user to predict how much solar power required to provide for daily flow requirement. In order to use this sizing chart, user need data from previous step to determine how much solar resource available per day in terms of kWh/m2/day or PSH. This will in turn decide how much solar power you require for the solar pump. Unlike the pumping head requirement, if the pump water flow capacity is lower (due to specification or cloudy day), it still capable to provide water eventhough the sun is not as bright (it will only provide less quantity of water).



Calculation of PV Panel Required

The calculation of PV panel number required should be based on the specification of the solar pump inverter input. Normally they will suggest a range of DC Input Voltage and inverter power required. The number of PV panel required is related to the specification of individual panel. The common misconception is that you can estimate based on the number of panel (they had different capacity) or size (it might had different efficiency).


Further Information


References

  1. ↑ https://energypedia.info/index.php/Photovoltaic_(PV)_Pumping
  2. ↑ http://www.pacinst.org/reports/basic_water_needs/basic_water_needs.pdf
  3. ↑ http://www.drfn.info/docs/cbend/energy_factsheets/solar_water_pumps.pdf
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