Last edited: August 2018
Buying a Solar Water Pumping System in Tanzania
Step 1 - Selecting the solar (water pumping) company
As you can see on this page, there are many companies in Tanzania which are selling solar power systems. Quite a few of them, mainly the companies involved in customizable solar solutions, are also installing solar water pumps. Please note, though, that installing solar water pumps requires the company to also master a completely different skillset (water and electricity do normally not go well together!). As such, it is particularly important to review their experience installing similar systems in the past. Aside from solar companies installing solar water pumps, there are also drilling companies which supply solar water pumps.
In case you want SmartSolarTZ to bring you into contact with a suitable supplier, please use this contact form.
Step 2 - Stating your requirements
In order for the solar (water pumping) company to be able to ask you the right questions later, it is important for them to know about your expectations. It would be good to talk about:
- Performance of the system - When do you need water, and if you want power 24/7, how critical is it that you can always rely on the system (even in times of lots of cloud cover).
- Timeline - When do you expect the system to be installed? Especially for larger systems it is often required to import components from outside the country.
- Budget - If you have a set budget, it could be good to share this to ensure the company is proposing a system which is aligned with what you can pay. In case you share your budget, do ensure that you ask for multiple quotes from different companies.
- Financing - Some companies provide options to finance your system and pay for the system or for the electricity it produces or the water it pumps up over a set time period. If you are interested in a financed system it would be good to mention this.
- Time horizon - Do you want a system that lasts for the coming 2, 5 or 15 years?
Step 3 - Data collection for a solar water pumping system
After your preferences have been stated the solar (water pumping) company should ensure they gather sufficient data and information to start the design of a system that meets your requirements. Important data to provide the company with is:
- Water usage - How much water are you using or do you expect to be using, and what will you be using it for (drinking water, irrigation, etc)? This is easiest when you are currently already pumping water with, for example, a diesel generator. In case you are not currently using any water the solar water company should be able to make some predictions based on your input (for example, the number of people or cattle drinking the water or the surface area of crops which need to be irrigated). Water usage is normally stated in liters or cubic meters (m3 = 1000L) per day.
- Vertical distance - The vertical distance is the amount of meters the water needs to be pumped up. Depending on definition, this is also called lift or head. The total dynamic head (TDH) combines the vertical pumped distance (both “sucking” water as well as “pushing”) with the friction losses which gives the TDH in meters.
- Horizontal distance - Aside from pumping the water up, how far does the water need to be transported over the ground?
- Future plans - Often it is much more expensive to upgrade a system in the future compared to building a slightly larger system from the get-go. Make sure that the solar water pumping company knows about any expansion plans you might have.
- Location of components - Where will the solar array be located? Is it possible to use an existing roof for this, or should it be located in the field? In case of pumping from a lake or river, what is the best place to put the pump? What is a good (high) place for the water storage tank and distribution piping?
- Water quality - Especially when pumping from a pond, river or lake it will be necessary to know whether special precautions need to be taken to prevent dirt from clogging up the solar water pumping system.
- Pipe diameters - Especially with long distribution pipes, it will be important to know the diameter of the pipes to include this in the calculations for the power needs of the pump.
- Size of storage tanks - When storage tanks are already in place, the solar water pumping company would need to know about the size of these storage tanks (in liter or m3).
- Borehole yield - In case of pumping from a borehole, the yield of the borehole (in liters/hour) is the most important factor. Normally a pump test is performed after a borehole has been drilled. The pump test report should provide all the information necessary for the solar water pumping company.
- Communication - In order to include remote monitoring, you will either need to provide an internet connection (wifi/LAN) or have a GPRS signal from a telecom operator.
- Maintenance - Are there normally technicians or people around already performing maintenance on other equipment?
- Location - The solar company will need the exact location of the project in order to match it with local/regional weather and <irradiation data>.
Step 4 - System design
Especially in case of larger systems or when it is hard to provide all the necessary information, the solar water pumping company might visit the site. Subsequently, they will use the gathered input to come up with a system design. Due to the complexity of the calculations, the company would normally use specialized design system to make the design.
Based on the design a quotation will be created.
Step 5 - Comparing quotations
Comparing different quotations can be tricky. You will need to pay close attention to the system design in order to understand whether all the input variables are used properly. One company might somehow tweak the design and promise 30% more water pumped, however, before you find out whether the system actually performs as expected you have probably already paid the system.
Depending on you own level of expertise and the total order value you could consider getting assistance in reviewing the quotations. SmartSolarTZ (contact us) has been reviewing quotations for many years and can provide you with the necessary insight to be able to make an informed decision.
Step 6 - Installation
Normally the solar company will start preparations for the installation after receiving a down payment. Please note that not all materials are stocked by solar companies in Tanzania. Some companies stock the solar water pumps and controllers in East Africa, however, since there are so many pump combinations it might be tricky. Since the solar water pumping system is not particularly heavy, it can easily be flown in. This means that an installation can normally start within a few weeks after the down payment.
After installation, ensure that you are given a proper explanation of the whole system and that the relevant people are training in the daily operation and maintenance of the system.
Step 6 - Remote monitoring
For larger systems and for systems which have a critical function it is strongly recommended to ensure that the performance of the system is monitored. This ensures that both you and the solar water pumping company which installed the system can regularly check whether the system is behaving according to expectation. If there is no internet, you can often still monitor the system locally by using a monitoring device. With monitoring it is possible to:
- Remotely identify (and sometimes fix) current or potential issues with the system
- Plan the use of your water in a smart way
- Get automatic messages in case the status of the system changes
- A history of high-quality data to see whether it is necessary to expand the system
Step 7 - Service and maintenance
Lifetime of a solar water pumping system
The lifetime of your solar water pumping system depends on a variety of factors, including: the use of the system, the (quality of the) brands used, the water quality, the settings of the different components, and the maintenance performed. Generally speaking, you should be able to expect the following lifetime if you are using high-quality brands, have good water quality and are performing regular maintenance:
- Solar Panels: 25 years, all Tier-1 solar panels are made to last a long time
- Solar Pump Controller: 5-10 years
- Solar Water Pump: 5-10 years
Service and maintenance of solar water pumping systems
The solar array does normally not require much maintenance, only when they easily get dirty it could be good to clean the solar modules once in a while (with a soft cloth and ideally demineralized water) during the dry season.
With regards to the solar water pump, you ideally fit & forget. This should be possible in case the water quality is good and the pump is monitored remotely. If this is not the case, however, it might be necessary to occasionally clean, check or repair the pump.
In case a generator is integrated into the solar water pumping system, this part of the system would require more maintenance. Aside from the daily checks, it would be required to change the oil and filters at regular intervals (generally every 250-500 running hours).