This solar submersible pump system is being planned to be integrated with a drip irrigation system. So keep in touch for future updates about future project.
For a productive farm to sustain, one must have a constant and reliable source of water safe for drinking, consumption and other. That is where water is everything to every human, animal and plant in the rural community.
I used to fetch 2 gallons of water across our rice field when I was young. Before, nearby water sources cannot supply enough water and they deplenish very fast. So I need to cross a 500m rice field carrying 2 gallons of water per trip which means 6 gallons of water a day. Can you imagine how exhausted it was? Rural area practices aren’t practical in anymore. That’s the only available means of transporting water at that time.
Our farm depends on a hand pump very exhaustive of human power. Our farm is situated on a hill elevated from the nearest well at about 7m and a distance of about 50m away. With this problem, I need to find a solution.
I have made a lot of options then. One of which is a mechanical windmill that will suck water upward, free energy from the wind, since our area has a great potential for high wind density. But upon checking the internet, the price of windmills are horribly expensive, even those simple ones. Another option is a gravity fed water source from a nearby mountain, which is actually near the well where I used to fetch water from. Apparently, the distance is about 1,000m; possible for a hose but unsafe for hunters and passing mangunguling (charcoal makers). Some of them, when they got thirsty, they chop the hose along the way and drink from it. Very unsafe and unsecure.
But I discovered this better idea of pumping water, free energy from the sun, affordable and sustainable. A solar powered submersible pump. It’s kind of new in our local, even the solar part is not popular there. I’m introducing these systems in our area for them to witness how technologies could help them in their farming activities.
Here’s a list of the things at our farm that greatly demands water supply for everyday use:
- Calamansi trees. These small trees need about 4 gallons a day with scheduled irrigation every 7-14 days every sunny season and 10-20 days every rainy season.
- Vegetable Garden. A small vegetable garden comprising of a few radish and squash.
- Flower Garden. My mother loves to plant some local flowers and orchids. She water them every morning.
- Small Livestock. Needs to be cleaned everyday so lots of water is needed.
- Small Poultry. Would not consume that much water, but essential for chickens as well.
- 2 Households (10 people). Two houses comprising of our house and my sister’s.
Let’s proceed to our main goal, to build a solar pump system. These are the considerations why I’ve chosen a solar pump compared to other alternatives:
- Cheap – farmers would be capable of availing the system at lower costs, payable through lending and recurring payment options
- Lifespan – longer lifespan to compensate the initial capital required to build a solar pump system
- Interfaceable with farmers – farmers can operate easily with less hassle
- Operation & Maintenance – low annual operation and maintenance that would compensate initial starting cost
- Sustainable – production lifecycle of the products, processes and operations is sustainable
- Portability – there are some cases where water supply can be found on a much remote place. The submersible pump along with the panel and components could still be made portable. Helpful for nomadic type of farmers.
Calculating Water Supply Demand
First thing I did was to consider the water needed to supply the farm’s needs. This includes the calamansi trees, a small livestock and poultry and 2 households with 10 persons in total. There are two households which includes our home and my sister’s. Using the information in designing water tanks from lifewater.org, an estimation is given of how much water each of them would consume in a day.
Estimated water consumption per day:
Household: 2 houses, 10 persons * 25 L/person = 250 L
Livestock: 10 pigs * 15L/pig = 150 L
Poultry: 30 chickens * 0.25 L/chicken = 7.5 L
Est. no. of calamansi trees: 200 trees * 12 L/tree / 7 days = ~350 L (Equivalent of once a week irrigation)
Vegetable and Flower Garden (varying plants): 50L
TOTAL Demand = 807 L
Sun hours is the estimated useful number of hours that the sun could provide a sufficient amount of sun energy in a day. It varies per region and per parts of the world. In the Philippines, the estimated sun hours is 5 hours.
I propose to build a small pump system powered by solar energy. Taking advantage of the calamity’s intense solar effects, we could build a standalone solar pumping system to mobilize water. To get started, let’s discuss one of the important aspects in determining the specifications for each component, knowing the water demand and its load implications.
For the calamansi trees, it would be easier if the water should be transported directly through an irrigation system. A drip type irrigation system would be essential in delivering the water to the calamansi trees. The discussion about the drip irrigation system for calamansi trees will be available in the future posts to come.
Choosing the Components
From the previous calculated water supply, we must have about 800L of water in a day to fulfill the farm’s water needs. We have to find a pump that would suit the following requirements that we have mentioned previously:
- Capable of 12V input compatible with solar panels and controllers
- Can lift water at 10m elevation
- Capable of delivering water from a well
- Capable of delivering 800L a day at 5 hours (sun hours)
- Reasonable prices for farmers to afford
Searching on the internet, we have found a good pump that satisfies our criteria. I found a pump through a manufacturer from Alibaba. It has a rating of 12V, 4A max. submersible solar pump with maximum water displacement of 70m. At 10m, it can lift 204L/hour (1,122L/day, nonstop 5 hour).
To properly take good care of the pump, the pump must be operated at a maximum of 2 hours and shall rest for 30 minutes to prolong its lifespan. Subtracting another hour (2 * 30min. rest) to the pump would lead us to only 4 hours of total day operation (816L/day, 4 hour with 1 hour rest). I ordered one from Alibaba and it shipped from China.
Let’s look at the pumps specifications. The pump has a minimum power rating of 28W at 10m. At a maximum elevation of 70m, it requires 72W of minimum power rating for the solar panel. At this instance, I will be basing with the maximum elevation of 70m in cases we might need to deepen the well or move the pump system to another deeper well. I’ve chosen to use the 100W panel since its the next wattage value of a commercial solar panel available above 72W.
Even without a charge controller, the pump is still capable of using the energy directly from the panel according to its specs. I’ve added a charge controller just to make sure that it would optimize the pump’s current requirement.
I’ve found a good controller from Sun Magnet in Dasmariñas, Cavite and bought it personally from their stock house. It’s a 10A, 12V/24V adjustable regulator I bought at around ₱1,000. The pump and the panel is 12V, perfect for our system. This charge controller has a timer and can be configured according to how long you would use the load in terms of hours.
Adding a battery would make a great setup. Requiring a deep cycle battery would still depend on your application of the pump. In our case, we’ll only be using the pump on a daylight and be storing the water in a huge container thus, the battery will serve as a buffer from the panel to the pump.
The diameter of the wire you choose depends on the current that would flow in it and the length of the wire needed. Use a wire chart to properly use the appropriate wire size (diameter) considering the current rating and length of the required wire. There are many great wire charts around you can search on the internet to serve as your reference.
Most of the parts like enclosures, mounts, etc. were done with their DIY alternatives in order to even lessen the cost of this small system. Why purchase at a store if the materials are available locally? Additionally, our main objective is to lessen total cost as well.
Building the DIY Panel mount
My father and a local carpenter, Manong Boy helped us in the construction of the mounting. The base was made from a local wood called madre de cacao (Gliricidia sepium). It’s oftenly used as columns for houses in our local area.
We identified the angle of the panel with respect to the horizon through experimentation. We varied the angle and measuring it at the same time.
Building the housing
We found a perfect housing for the charge controller and the batteries, an empty container used to carry oil and liquids. It is also often used in Philippine rural areas as pail for transporting and storing water. We washed it very well at first to remove the remaining oil on its internal surface. We transformed it into an enclosure. It was attached underneath the solar panel to add additional protection from rain and extreme sunlight for the components.
Rope, hose and wire assembly to pump
There are three components attached to the pump. The hose transports the water to the desired location. We based the length of the hose according to the depth of the well and the distance of the well going to your storage tank or any container. The wire powers up the pump and attached therein the two wires according to polarity. The rope carries the weight of the pump. A polypropylene rope was used to carry the overall weight of the pump to avoid being stretched out. Avoid using a nylon rope which stretches and may transfer its weight on the hose and wire.
We made sure to measure the depth of the well before attaching the components. First, we tied the rope through the two holes at the top surface of the pump. Next is we attached the noseclip on the hose opening to make sure the hose would have a tight grip on the pump water opening. Finally, we soldered the two wires. The pump I bought already had built in wires which were made to be waterproof or submersible under water.
There are 4 holes on the back of the panel aluminum frame where you can attach a nut and bolt. We drilled the wooden frame corresponding to the location of the 4 holes. The panel was then attached to the wooden frame, pretty sturdy and strong.
Submerging the Pump
Before submerging the pump, the tension was put on the rope, not onthe wire and the hose. Take note that the pump can only be submerged at a maximum of 30m according to spec. You can also add a sand sock wrapped around the pump to make sure no foreign object such as sand or small rocks could get inside the pump.
Connecting the Wires
Let’s go into our container housing and connect the wires. First, we connected the charge controller to the battery (very important). We have 2 pcs 7Ah at 12V battery which is the only battery available when we bought them. I connected them in parallel to acquire the same 12V level.
Next is the solar panel and lastly, the pump.
I have received an email from the supplier that you can directly connect the panel to the battery pins, which means it will get directly the power supply from the panel. A batteryless system yet I still haven’t tried it.
Just to make sure stray animals or someone interested wouldn’t be interested in stealing the components and getting near the system, we surrounded the setup with a fence.
Test & Evaluation
It was a success on our first attempt to make it work. Here’s the video for the demo:
Solar vs Diesel Pump, How Much Could You Save?
In this section, we’ll evaluate how much savings you would get when you use a solar pump compared to a diesel pump counterpart. Note: This is a rough estimate and inflation rates haven’t been considered. Total net cost was based on the 5 year operation between a Solar pump and a Diesel pump. We compared it into a diesel pump since it is the most commonly used in our local area.
Let’s estimate the cost savings based on a 1,000L/day water output and 1,500 hour a year of operation. Diesel costs in the Philippines is ₱26.25/L. Electrical pumps, such as solar pumps, can operate at 80% efficient while Diesel pumps typically has 33% efficiency.
Solar Pump operates at 4hrs a day at 2.5A, 12V. Energy consumption is at 120Whr/day * 365day/year would be 43.8kWhr and would require 43.8kWhr / 80% = 54.7kWhr.
Using a specific diesel consumption of 0.3 L/kWh (33% efficiency). With 43.8kWhr required to elevate water, we need an input of 43.8kWh / 33% = 132.72 kWh. The annual diesel consumption is 132.72 kWh/yr * 0.5 L/kWh = ~67 L/year.
|Pump||Initial Cost||Operating Cost/year||Total Net Cost after 5 years||in USD|
|Solar Pump||₱17,000||₱0 fuel cost
|Diesel Pump||₱8,000|| ₱25 / L *
67 L / yr
= ₱1,675 / yr₱4,500 maintenance
Diesel price increases each year, unlike the solar panel no recurring fuel is needed to be purchased since the sun supplies it for free!
Based on a study comparing solar pump and diesel pump, you can save about 1/10 to 1/4 of the total net worth cost when you use a solar pump system. For a more comprehensive info on cost savings, please refer to this research paper title Solar and Diesel Powered Pumps: A Cost and Reliability Comparison.
Issues and Concerns
As we mention previously, the well becomes shallow every time we continually use the pump for an hour and it replenishes to its previous level after half an hour. So, we have to wait for another half an hour in order to make use of the pump again. The pump shouldn’t be operated without water for a long period of time. To solve this, we deepened the well to increase the capacity of the well’s reservoir.
Another issue is that to turn on and off the pump, one should go to the well where the housing, panel, and charge controller is located. We’ll be adding a wireless remote that could turn on and off the pump by a push of a button in the future.
The components and materials were purchased from different stores locally, except for the pump which was availed through Alibaba. There are also locally available solar compatible pumps but the prices were ridiculously high since it was a newly introduced product here in the Philippines.
One of my objectives is to construct a reliable solar pumping system while minimizing the cost at the same time so that farmers would also be capable of having a small pumping free energy system.
Here’s the breakdown of prices from this phase of the project:
|Component||in PHP||in USD||Source|
|Submersible Solar Pump + Shipping + Customs Tax||₱6,175.00||$135||China|
|100W 12V Solar Panel||₱2,990.00||$65||CD-R King|
|10A Charge controller PWM||₱998.00||$22||Sun Magnet|
|2 7Ah 12V Deep Cycle Battery||₱1,160.00||$25||Tech Home Iloilo|
|15m 2.5mm dia . Electrical Wire||₱840.00||$18||Sun Magnet|
|1/2″, 55m long Hose||₱1,375.00||$30||Iloilo|
|1 MC4 Connector||₱62.00||$1.40||Sun Magnet|
|7m Polypropylene Rope||₱35.00||$0.80||Hardware Iloilo|
|Submersible/waterproof Tape||₱360.00||$7.80||Ace Hardware|
|Electrical Tape||₱30.00||$0.65||Ace Hardware|
|Royal cable #18 0.75mm||₱350.00||$7.60||Ace Hardware|
|Fuse holder||₱33.00||$0.72||Ace Hardware|
|Fuse 8A 5pcs.||₱20.00||$0.43||Ace Hardware|
|Nose clip||₱10.00||$0.22||Hardware Iloilo|
|SUB-TOTAL – completed on April 14, 2016||₱16,363.00||$357.72|
The overall technicalities on a solar pumping system is not that hard as you think. With proper research, analysis and sourcing of materials, you could come up with an affordable way of cutting cost and build a sustainable water supply. Solar pump system also provides greater savings in the long run.
The next project I have in mind is the drip irrigation for the calamansi trees . Stay tuned for the next posts.