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LAKE MICHELLE ESTATE IN CAPE TOWN IS LOCATED WITHIN A NATURAL ESTUARINE ENVIRONMENT IN NOORDHOEK. THE ESTATE IS BUILT AROUND A LARGE LAKE THAT FORMS PART OF THE NOORDHOEK WETLANDS, WHICH CONNECT TO THE NOORDHOEK ESTUARINE SYSTEM.
This ecosystem supports diverse birdlife and various aquatic species, making it an environmentally sensitive area, therefore the management of the water and sewage is critical to the HOA team.
AWPower is proud to showcase its innovative solar-powered solution that manages critical water and sewage pump station infrastructure at the Lake Michelle eco estate in Noordhoek, Cape Town.
AWPower engineers and members of Lake Michelle’s Alternative Energy Committee have successfully designed, tested, and implemented a decentralised solar system to address the estate’s critical infrastructure needs, supporting the administrative building with security systems as well as six sewage pump stations. By designing a decentralised solution, substantial savings were realised compared to a large central system, and the decentralised approach provides a lot of room for future upgrades and expansion.
The primary purpose of the system is to support the estate’s sewage pump stations with solar-generated power, and each sewage pump is fitted with a dynamic solar pumping inverter to manage and automate the operation of the pump and to provide full digitised remote management and control capabilities. In addition, solar-generated power is used to support several high-capacity water pumps that are moving water between the main lake and ponds to maintain water quality.
At its peak during summer, and when excess generated power can be exported to the grid, each decentralised solar system will be saving about R5,500 per month at the current cost of electricity, achieving a payback of less than four years.
Set against the backdrop of Lake Michelle’s pristine 22-hectare freshwater lake, this ‘Out of Africa’ solution not only meets the estate’s sustainability goals but also ensures a reliable and efficient water management system.
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THE ESTATE’S CHALLENGE
A typical problem facing an estate such as Lake Michelle would be the risk of failure of the electric sewage pumps, in this case consisting of six pumping stations in series, to remove sewage from the estate.
Should there be no electricity to drive the pumps, or should the pumps fail to operate, the risk of polluting the freshwater lake will increase, having a disastrous effect on the pristine environment, including a diverse birdlife community, fish and wildlife.
Before being upgraded to solar, each pumping station was equipped with two three-phase 5kW submersible pumps controlled by an array of switchgear housed in a metal kiosk, and the level of fluid in the sewage chambers was measured by float switches submerged into the sewage chambers or sump.
Should there be a malfunction or failure, or the float switches become clogged with fatty deposits, the ‘old’ system may activate an alarm under certain conditions, and this audible alarm with flashing light may signal a need for maintenance personnel to intervene, which could be in the middle of the night, especially following a heavy downpour when sewage chambers are typically prone to being overloaded.
A major problem facing maintenance staff is that they have no insight into the actual level of the sewage chambers, nor the condition of the switchgear or either of the two submersible pumps installed in the chamber, unless they open the hatches and physically look at the levels. If a component in the traditional pump station fails, the first sign could be a spill of the sewage sump into the surrounding area.
Many of us living in South Africa are very much aware of this common phenomenon that our government and city councils seem unable to fully control.
THE MODERN SOLUTION TO SEWAGE PUMP MANAGEMENT
AWPower engineers conducted international research into the modernisation and effective management of pumping stations. Solartech was recommended as a class-leading manufacturer of solar pumping inverters, and through designing a prototype system to replace the traditional pump station switchgear, and testing it for several months, a final inverter-based pump system was designed to replace the old traditional mechanical systems consisting of float switches and elaborate switchgear.
Without getting into technical details, the solar pumping inverter replaces all the functions provided by the traditional pump station switchgear housed in the black kiosk, plus more, including cloud-based remote monitoring and control, providing a cost-effective and reliable solution for Lake Michelle.
The solar pump inverter connected to the sewage pump becomes the ‘brain’ of the submersible pump, becoming a fully digitised and programmable solution that measures the level in the sewage sump, switches the three-phase submersible pumps on or off, runs the pumps alternately, or together if the level in the sump is abnormally high.
The pump inverter will sense when the submersible pump reaches an abnormal temperature or if there is water ingress, or if there is an imbalance in the three-phase electricity supply. And all of this data is transmitted to a cloud-based information storage and reporting system, via a built-in wireless communication module connecting to the cellular network, allowing full remote monitoring and control of the pump stations.
WHAT WE DESIGNED AND INSTALLED – THE MAIN COMPONENTS OF LAKE MICHELLE’S SOLAR-POWERED SYSTEM
The systems installed (some scheduled for 2025) at Lake Michelle include the following main components for most of the six pump stations around the lake:
SOLAR PV ARRAY
Solar PV array of about 11kWp per pump station — ground- mounted poles with gum latte fencing to blend in with eco environment. Some pump stations will be sharing solar PV array and inverters once phase 2 of the installation programme commences.
FOX ESS 30KW HYBRID INVERTER
Fox ESS titanium 30kW hybrid inverters were selected for Lake Michelle because of their competitive price, silent operation, and their IP65 rating, meaning they are fully weatherproof, allowing the system to be installed outdoors. Also, Fox has the reputation of producing the safest lithium batteries on the planet; they have triple level fire protection, making them safe to install in the eco estate where fire safety is a key requirement. The units installed provide 10kWh of battery storage, expandible up to 86.32kWh. The hybrid inverters have 3 MPPTs each, and up to 10 inverters can be connected in parallel to allow for future expansion up to 300kW. Each system is equipped with a mobile Wi-Fi router to facilitate communications, including remote monitoring and control.
The weatherproof features of Fox ESS allow for the systems to be installed outdoors near the pump stations, with limited need for expensive cabling that would be required from a conventional solar PV installation. The result is a cost-effective, decentralised and scalable solution spread over an area of about 45 hectares of land and freshwater lake area, with an ability to be expanded to support most energy consumers on the estate, thereby reducing future requirements for electricity from the grid, with large savings potential.
The inverter, batteries and switchgear are all housed in a weatherproof enclosure, constructed from timber poles and covered with treated gum latte, providing a rustic appearance that blends in with the environment of the eco-friendly estate.
SOLARTECH 7.5KW SOLAR PUMP INVERTERS
Each pump station is equipped with two Solartech pump inverters, each with 6m liquid level sensor submerged into the sewage chamber, connected to a sewage pump. Although the Solartech pump inverters are IP65 rated, they are housed in IP65-rated boxes (the ‘Orange Box’) to provide extra protection for switchgear mounted inside, together with pump inverters. The Orange Boxes are mounted to the back of the previous generation of black switchgear kiosks. The two boxes are mounted back-to-back on top of the sewage chamber. Each pump inverter is equipped with a communications module with SIM card that facilitates remote monitoring and control of each of the two sewage pumps with matching solar pump inverters, providing a fully digitised solution.
Apart from remote monitoring and control capabilities, the Solartech pump inverter also allows for access to managed functions through its keyboard and screen, which allows for maintenance staff to operate, view and diagnose during typical on-site maintenance functions.
Being a fully digitised and simplified solution with fewer moving parts, all information on pump station status is available on a mobile device or laptop PC with large screen for security staff to watch.
PUMP STATION MONITORING DASHBOARD
Monitoring is essential for managing pump station performance, and to this end AWPower developed a monitoring dashboard that will keep security and maintenance staff members fully informed, without having to leave their office or home.
The online dashboard collects data from a cloud-based solution where data from each pump that is connected to a pump inverter is stored and made available 24/7 in the dashboard below:
Direct savings generated — an example
Apart from providing energy security in the event of loadshedding or grid failure, the cost savings from using solar to support all the sewage pumps, pond water pumps, irrigation pumps, administration and security could be significant at Lake Michelle. The interim information from the remote monitoring app for the Fox ESS 30kW system supporting Pump Station 3 (Milkwood) for November 2024 provides the following insight:
Energy consumed during Nov 2024: 1.8MWh Energy purchased from grid: 294.0kWh Self-sufficiency: 1.5mWh
Savings generated Nov @ R3.00/kWh = 1.5MWh x 1,000 x R3.00 = R4,500 (Incl. VAT) savings for November 2024
Once exporting to the grid is approved and the relevant equipment is installed by City of Cape Town, Pump Station 3 could be expected to export at least 30kWh per day, for example in November, which would yield further savings of approximately:
30kWh x 30 days x R1.1713 = R1,054 savings per month Typical November savings: R4,500 + R1,054 = R5,554 Note: Expect lower savings during winter.
WHAT OUR CUSTOMER IS SAYING
‘We are proud to be associated with AWPower. The company went out of their way to assist and design new user-friendly technology through solar and pump inverters, that will help manage our sewer pump stations, resulting in huge savings. They went the extra mile to ‘think outside the box’ and help us become the first estate in the country that will be using the technology they introduced to better manage sewer levels and create savings, making us a leader in the industry. Their workmanship is of the highest standards. We can recommend AWPower to any company and welcome you to call us to discuss our successes.’
Henri Hattingh
Executive Chair of AWPower
A green future of energy and water independence, Lake Michelle’s decentralised solar PV and solar pumping solutions exemplify how innovation and sustainability can go together. By leveraging renewable energy and advanced technology, AWPower has provided the estate with a reliable, cost-effective, and eco-friendly system that safeguards its natural beauty while addressing critical infrastructure needs and energy independence. This decentralised and innovative approach could be applied to most residential and commercial estates, golf courses and estates, and farming communities, allowing a first step towards a smarter, sustainable future that leads to energy and water security.
Henk Booysen
Estate Manager, Lake Michelle Homeowners Association (Noordhoek, Cape Town)
‘It was exciting for the AWPower engineers to expand their skills into water engineering services, and specifically into pump station management. We’re proud of the work our team has done and completed for Lake Michelle. In South Africa, we have an urgent need to optimise the use of water, and in particular pump station management. By leveraging our team’s solar and engineering skills, we can provide innovative designs that can assist with optimising the use of water, thereby also assisting with improving the quality of water. By adding the products and solutions from brands such as FoxESS and Solartech with their unique features, we can design cost-effective solutions for any residential or commercial estate, golf estate or farming community.’
