Optimising efficiency of solar-powered pumping systems

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Dec 2, 2020

Optimising efficiency of solar-powered pumping systems

BMG’s electromechanical specialists, with extensive experience in gearing, have extended their solutions service to include solar inverters and drives, which are designed to enhance efficiency of photovoltaic (PV) systems.

“PV modules – which use daylight to generate electricity – are gaining popularity globally as a form of renewable energy that is clean, emission-free, sustainable, safe and cost efficient. Through the use of environmentally-friendly PV technology to generate electrical power, companies in South Africa are finding effective solutions to combat the country’s grave electricity crisis,” explains Mick Baugh, electronics manager, BMG’s electromechanical division.

“The benefits of using eco-friendly solar powered pumps for irrigation, animal farming and community water supply, include an uninterrupted water supply during the day and independence from the unreliable grid. In addition, advanced PV systems require minimal maintenance, which is an important advantage in remote areas where servicing is difficult.

“ Solar-powered pumping systems, which are particularly popular in remote areas where electricity is unavailable, require a solar inverter to convert direct current (DC) generated by solar panels into alternating current (AC) for use in industrial, commercial and residential applications. A key differentiator in the selection of the correct inverter, is its ability to run the motor pump at the optimal working voltage and power ratings, to ensure solar panels deliver the highest possible power in various irradiation and ambient temperature conditions.

READ: Egyptian farmers to access solar irrigation pumps funding

“For optimum performance of the PV pump system, we believe it is critical for users to fully understand the control strategy of the system and to consider factors like where to install the drive, condensation issues, the temperature range and the back-up supply.”

Control strategy
Simpler solar-powered drives for pumping applications operate as under-voltage regulators, lowering the pump speed (thus reducing the absorbed power) when the DC voltage reaches a minimum voltage set-point. This simple control mode negatively impacts performance of the PV modules, since they operate at a non-optimal voltage.

In advanced controllers, the drive works to obtain the maximum power from solar panels by keeping the DC voltage at the optimum point (MPP = Max Power Point). Drives that operate at a constant DC voltage must be selected depending on the electrical characteristics of the installed PV system and should optimise the hydraulic efficiency of the pump.

BMG specialists recommend the use of Vacon solar-powered drives that feature MPPT (Maximum Power Point tracking) control to ensure an optimal operation voltage for PV modules in pump applications. These highly-efficient MPPT controllers provide extended running hours, with an earlier start and later stop. Consequently, more water is pumped per watt peak (Wp) of installed PV modules, leading to reduced investment costs and a quicker payback period. MPPT controllers detect instantaneous irradiance or temperature variations and omit local maximums, which are generated in partial shading conditions or from degraded modules in the PV array.

Cabinet or outdoor installations
Conventional solar pump inverters are usually IP20 or 21 devices that are installed inside a cabinet along with components, including fuses, a power switch, lightening protection and door-mounted LEDs/bulbs. BMG specialists do not recommend this system because cabinets need to be ventilated to avoid overheating of the enclosed elements. Overheating produces derating and reduces lifetime of the drive. Airflow though the cabinet needs to be filtered to avoid dust collection and filters must be periodically cleaned and replaced, which increases risks and adds to maintenance costs.

READ: BMG Motoline solar inverters for PV water pumps

BMG’s Vacon IP66 drive solutions for outdoor installations consist of a small enclosure (replacing conventional big cabinets) which are separated from the drive – to house the mains switch and surge protection device. The Vacon IP66 drive can be installed outdoors without any reliability risk and does not require maintenance, as there are no filters to clean or replace. Drives can be mounted in the same structure of the PV modules, taking advantage of their shading to avoid overheating and thus a derating, due to direct sun on the drive.

This ground-level system is fitted with Light Emitting Diodes (LEDs) which allow external visibility of operating conditions of the drive, including power-on, run, ready and fault. An IP66 display panel provides detailed information of the drive, like running speed and MWh readings.

This enclosure, which is separated from the drive, gives the installer flexibility when designing a cabinet that is suitable to run a pump in different layouts.

Condensation
In conventional solar-powered pumping installations, intermittent operation during the day and internal temperatures changes between night and day, promote cyclical condensation-evaporation processes inside of the drive.

IP 20/21 drives installed inside a cabinet are sensitive to internal condensation and require temperature-controlled heaters. This can be a problem in solar-powered pumping systems because an AC grid is not normally available on remote sites. For this reason, anti-condensation solutions that do not require an energy supply, should be considered.

An advantage of BMG’s Vacon IP66 IP 66/NEMA 4X drives for outdoor installations is they are well protected against the ingress of water and dust and a specially designed GORE® vent effectively prevents condensation, without the need for a heater.

Temperature range
Solar-powered pumping systems are normally installed in areas where high temperatures can be a problem for the PV system. For this reason, it is critical to consider the maximum ambient temperature on site when selecting the appropriate drive model. This maximum temperature should be contained in the operating temperature range for the drive – preferably in the range without derating, to avoid power losses and to extend the service life of the drive.

Users should take into account that the temperature inside a cabinet where an IP 20/21 drive is installed is always higher than the ambient temperature. It is important to consider the overheating effect due to direct sunlight if the cabinet is not mounted in the shade.

BMG supports its extensive range of electromechanical products with a technical advisory and support service, tailored to meet the precise specifications of contractors, designers and the end-user.

How to identify best quality water tanks in Kenya

Staff Writer

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Oct 16, 2020

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How to identify best quality water tanks in Kenya

Identifying best quality water tanks in kenya can be a daunting task especially with the saturation in the market, yet water plays a very essential role in human lives and the lack of it can turn disastrous.

According to UN Water, Water scarcity can mean scarcity in availability due to physical shortage, or scarcity in access due to the failure of institutions to ensure a regular supply or due to a lack of adequate infrastructure.

To ensure steady supply and availability of clean water, a convenient storage is important. Pumps Africa Magazine looks at best quality water tanks in Kenya that can be used for the above purpose.

The best types of water tanks are; Plastic water tanks and Steel water tanks.

Here are some of the features of best quality water tanks in Kenya.

Plastic Water tanks
For best performance, a water tank should be rust resistant to keep the water from being contaminated with rust particles. A rust resistant tank will also serve for a long time hence durability. When buying steel tank for water storage or any other purpose, always go for stainless steel.

The tank should be able to total block UV light (sunlight) so that water growing plants like algae, and other living organisms that require sunlight to survive in water will not have a chance of living in the tank. This leaves the tank’s water safe for drinking.

Black plastic water tank is recommended for purpose of UV light protection.

A good water tank should be easy to clean as overtime, solid dirt from atmosphere and the collected water settle at the bottom of the tank.

READ: Best Water Tanks in Kenya – with contacts

Durability is key for long service life; look out for water tanks that have to warranties as they will not serve you for a long time. Some manufacturers will provide warranties and guarantee specific number of years a tank will serve.

Plastic water tanks are preferred for various reasons including: ease of installation, durability, UV light blockage design, availability in various sizes and capacities, costs, ease of cleaning and low maintenance.

Always ask the supplier or manufacturer for installation guidelines when buying your plastic water tank.

Preet Chheda, CEO Vectus Kenya Ltd advises that plastic tanks should only be bought from manufacturers who use UV material. He clarifies that UV material can be any other colour but the preferred option should be black.

“The best way to drill the outlet or inlet, would be by using a drilling machine, this will keep the warranty of the tanks safe and will also not damage the tank due to a change in the temperature,” he adds.

Steel water tanks
Steel water tanks, however not as popular as the plastic water tanks, are also a good choice. They are highly durable, stainless steel tanks are rust resistant, unlike other metallic tanks. They come with big water storage capacities, most steel tanks are used for community water supply or by municipality water utilities.

They are free from UV light penetration as they are sealed in all sides and the shiny surface helps reflect sunlight.

Steel tanks can be installed on the ground, underground and can also be raised. Each installation mode has specific guidelines that should be followed to ensure proper and sage installation. Always seek for professional services when installing your tank.

How to check for durability
Chhed instructs that the best way to determine the quality of the tank, is to check and compare the weights of different tanks from different manufacturers. “The simple rule is, the more the weight of the tank the thicker the walls of the tank are, so more strength to withstand the pressure of water.”

He advises against pressing the tank on its sides to determine how light a tank is in weight. The best way, he recommends is to look out for the total weight of a tank. The lighter the tank, the less likely it is to hold the pressure of the water that is stored within.

Top 5 water meter companies in Kenya

Staff Writer

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Sep 10, 2020

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A water meter constitutes a significant input in the normal operations of water utilities. The meter bridges the gap between the demand for water (consumers) and the supply of the service (water utility). It is the sole determinant of the volume supplied to the consumer. To the utilities, it is the sole determinant of the bill that should be levied against the consumed volume.

The challenge of Non-Revenue Water (commonly referred to as Unaccounted for Water) emanates in part from in accurate meters that do not register the actual volumes supplied to an area (to establish a water balance), to the consumer (for proper billing)and –subsequently-the efficient/effective management of available (often scarce)water resources.

In Kenya, there are laid down technical guidelines for water meter management – informed by international standards and leading practices of Kenyan water utilities. These guidelines are important to all stakeholders, particularly the Water Service Providers. They serve as a quality assurance to the consumers and the general public as to the specific intent to improve the reliability of water meters in use.

But who are the top water meter suppliers in kenya? Pumps Africa has outlined the following 5 water meter suppliers:

READ: Kenya set to automate water billing system

Dayliff water meter
The various Dayliff water meter types are robust and economical designs for monitoring residential, commercial and agricultural consumption. All meters are remote monitoring enabled and pulse cables are available on request. Sizes are available from DN15 to DN100 in three different ranges as follows: –

MJ – A high precision and reliable multi jet dry type water meter designed for general water supply metering applications. It features magnetic drive for lower transmission resistance, a magnetic shield for external magnetic field protection and a sealed dry dial to ensure clear and easy reading. The body is made from composite plastic for DN15 and DN20 sizes and brass for larger sizes. Meters are supplied with inlet strainers and union connectors.

PD – Rotary piston type meters that provide high accuracy over a wide flow range. The mechanical transmission movement provides reliability and the liquid sealed register provides easy and clear reading. Meters are fitted with internal strainers; non-return valves and union connectors and the bodies are made from composite plastic (15mm size) and corrosion resistant steel for other sizes.

WP – A heavy-duty meter with flange connections for bulk flow applications featuring magnetic drive, a dry dial for clear reading and a removable measuring mechanism that can be maintained without removing the meter body. The body is made from cast iron with epoxy coating.

Maji Milele
Maji Milele is a distributor of a wide variety of high-quality prepaid water meters. The prepaid water meters are used for communal water points, for domestic connections (also with AMR/AMI) and for purified water ATMs. All prepaid water meters are linked to mobile payment and come with an online monitoring system for tracking daily payments and water consumption. Online monitoring also helps to detect leakages and illegal connections and greatly reduces non-revenue water.

READ: Kenya Tech firm unveils “Vipimo Smart” meter that regulates water use

Maji Milele supply prepaid water meters from 3 different suppliers in the world, each with different features and advantages. The company’s premium supplier for prepaid communal meters is Susteq in the Netherlands, but they also sell similar meters from Iniative (India) and prepaid meters for individual connections from Laison (China).

Prepaid communal water meters come with 1 tap, 2 taps or 3 taps. Pepaid communal water meters can be used for hand pumps, water kiosks and stand pipes. The meter has many functionalities, like for example it works with flat tariffs as well as with variable tariffs, a maximum consumption per user can be defined. This is an alternative for water rationing in times of water scarcity. The meter moreover sends SMS messages to the water supplier in case of technical problems.

Prepaid meters for individual connections (0.5-10 inch) work just like prepaid electricity meters. Users top up by mobile money; they get a 20-digits code on their phone, which can then be inputted to the meter. When the user is almost out of water, 2 alerts are sent to the phone, by not topping up in time, the valve automatically closes.

For water service providers this means; no need for water meter reading, no need for sending bills and no need to disconnect defaulters. The system works automatically to disconnect and to reconnect. Payments are made through mobile money – Mpesa.

Rift Valley Machinery Services Ltd
Established in 1987, Rift Valley Machinery Services (RVMS) for the last 30 Years has built a reputation on after sales service and is re-known for retail and distribution of high-quality machinery into East Africa.

The company stocks high quality Baylan water meters from Turkey. The meters come in two variants; post-paid and pre-paid and in regular sizes that are suitable for the African region. Rift Valley Machinery Services is the appointed dealer of Baylan water meters in Kenya.

Danco
Danco have partnered with a high-quality water meter manufacturer – Diehl Metering, Germany. Diehl metering have every solution from mechanical meters, (volumetric, single jet, multi jet, woltman type), ultrasonic and electromagnetic meters.

ALSO READ: Choosing the right metering pumps for water treatment

All Diehl meters are Automated Meter Reading (AMR) Ready – giving the entire solution for automated reading, from receiving the radio signal from the pulse emitter to providing the software to read and analyse the readings. This solution will directly reduce commercial losses and improve water supplier’s non-revenue water.

Top pipe
TOP PIPE is Africa’s leading manufacturer and supplier of HDPE piping systems and solutions. TOP PIPE systems are used in a broad range of applications such as plumbing, water supply, sewerage and wastewater, storm water and drainage, mining, irrigation and gas.

The TOP PIPE brand is founded on an image of quality and credibility. Recognized as the leading plastic pipe manufacturer, TOP PIPE continues to innovate new products for the building and construction industry.

TOP PIPE facilities have direct access to world-leading technologies which are constantly innovating to focus on the sustainable design and life-cycle approach for each and every product they manufacture.

TOP PIPE supplies B METERS, an Italian company that has been designing, producing and distributing instruments and solutions for measuring the consumption of water and energy used for heating and cooling, for over 25 years.

The yearly production currently exceeds 2,000,000 units putting B METERS in a leading position both at national and European level.

B METERS srl operates both nationally and internationally supplying the water companies, the industry and the private market.

The product range includes turbine (velocity) type single and multi-jet water meters with mechanical or magnetic transmission, Woltmann meters, irrigation meters, flow meters, thermal energy meters and heat cost allocators with direct reading or complete with integrated modules for the remote transmission of the consumption data.