Managing its own solar plants has given the University of the Free State lots of research data 

The University of the Free State (UFS) has adopted diverse measures to ensure energy efficiency. Not only do all campuses have solar plants, but one even boasts its own microgrid – the energy-saving LED lighting on its sport fields.  The UFS is now testing its initiative of cluster pumps at its residences to heat water.

During 2022, solar generated about 11% of their power across all campuses.  However, “despite all our efforts of becoming more energy efficient, installing solar and so forth, our energy costs have been on a steady incline during the last 10 years, and this is mainly attributed to rising interest in tariffs,” said Mr Nicolaas Esterhuysen, Director of Engineering Services at UFS.

This approach has provided excellent research opportunities, said Esterhuysen. “We have loads of data.” And, working with scientists at their university, they have already published their first academic paper about the microgrid on their Qwaqwa campus.

One distinguishing characteristic of UFS’s hybrid systems is that they exclude batteries.  “The biggest consideration was the initial cost. If we managed to raise funding, in 10 years’ time, we would have to replace those batteries,” said Esterhuysen.

The university has three campuses:

• Bloemfontein – the biggest and oldest;
• Qwaqwa – a large area but small footprint in terms of buildings; and
• South campus – offers gateway programmes for school leavers to access higher education, distance education, and short courses.

“All these campuses have at least one solar plant to assist with our energy savings. The plants are all grid-tied,” said Esterhuysen. Two of the three plants, of one megawatt each, were built next to each other. They connect directly to the university’s 11 KV internal grid. The first was completed in 2019.

Esterhuysen said the benefit of grid-tied plants is that the maximum generation of the solar plant coincides with the maximum demand on campus. That means “we are using all the solar power that we are generating at this stage,” the Engineering Director said. They plan to increase the capacity by another megawatt in 2024.

“I’m a big advocate of demand-side management energy-efficient technology,” said Esterhuysen. “It’s no use spending millions of rands on solar plants if we are still using energy inefficiently and still wasting power.”

The university’s three main demand-side management initiatives are:

• load management: non-essential loads switch off remotely on all campuses when the load reaches a set target;
• replacing sport lighting with LED: 28 lights on four masts now demand just under 80 kilowatts compared to the previous 224 kilowatts; and
• installing centralised heat pump clusters to supply hot water to residences: this is still in testing phase, to be switched on during off-peak periods to avoid the high peak tariffs.

UFS’s Qwaqwa campus has a microgrid, which is a diesel-solar hybrid system without battery storage. It has four sets of generators, a bulk diesel tank, and a spill slope for the diesel truck to park.

“By centralising the diesel generation with the solar plant, we are saving in terms of how we manage our diesel costs. And consolidating the generators into one plant lessens our maintenance, is much easier to monitor, and ensures that the generators are being used more effectively,” said Esterhuysen.

They are looking at ways to optimise the solar generation, especially during grid failures.  “That is our highest priority – to enhance the reliability of the entire system.”

Their next priority is to expand the load control.  “We cannot keep running non-essential air conditioning and heaters on generator power.”

1. Mr Ajesh Aheer, Sustainability and Utilities Manager at UKZN: “I assume you are using the Schneider PME system (The French multinational’s Power Monitoring Expert). What has been your experience of using it to manage this entire system?”Esterhuysen: “We are using the Schneider PME system, mostly for reporting and gathering our data. The actual control of the microgrid is done with custom PLC (a Programmable Logic Controller computer), which governs the generator and the solar contribution. But we are very pleased with the Schneider platform. We’re looking to expand it onto the Bloemfontein campus.”
2. Mr Kishore Gobardan: “What is the cost of the installation for one of these plants?”Esterhuysen: “A one megawatt solar installation would be about R15m, depending on your ease of grid connection, how close you are to every connection, fencing and so forth.  For the microgrid, we had to do extensive refurbishment on our internal 11 KV switchgear inside the substation. That pushed up our costs quite a bit. We had grid-tied solar constructed in 2022 so then we just added in the microgrid. Also, we already had two of the 400KV generators on campus. The cost for two new diesel generators and the tank was about R3m, and the switchgear was about R6m.”
3. Gorbadan: “What are our monthly running costs? Esterhuysen: “I can’t give you a good figure yet. We only commissioned the system fully in January. We’re still very much in a testing phase.”
4. Dr Sandile Koko, lecturer at Central University of Technology:  “Since you opted to install the heat pump to heat the water before peak hours, have you not considered also using solar collectors such as evacuated tubes or flat plate collectors for heating the water during the day?”Esterhuysen: “Not yet. We are first focusing our efforts on a grid-tied solar plant to ensure we use electricity at other residences but that is something we could investigate, in the future.”
5. Mr Mbambeleli Masala, Project Manager at the University of Johannesburg: “Is the communication between the solar plant and the generators a hardwired connection or wireless?”Esterhuysen: “It’s a hardwired connection. The custom PLC is situated in the substation building, and we have hardwired fibre, and from there it’s communicating to each of the individual inverters.”
6. Masala: “In the event of loadshedding, how exactly is the load sharing set up between the systems and the generators? Are the generators carrying the load, say 30%, and the balance fed by the PV?”Esterhuysen: “We do not like to load the generator less than 30% because glazing the pistons over a long, extended period will cause damage to the engine. So, the one parameter is you must not ‘under load’ – if we can call it that — the generators. The other thing we need to keep in mind is that at this stage we are producing 430 kilowatts from the solar. If a cloud passes over, and it’s only for that instant, our generation output drops by 300 kilowatts, and those 300 kilowatts need to be immediately picked up by these generators. So, frequency control is absolutely everything with this microgrid control system. “We find the inverters are much more capable of ramping up than the generators are at curtailing their load. These are technical considerations that you might not think of, at the beginning. And to simulate these things is also incredibly difficult because we are talking about dynamic simulation in a magnitude of seconds. We need to get the balance between having a reliable and stable generator supply with the solar plant to get the best of both worlds.”
7. Gobardan: “Has this benefited you in terms of cost reduction, taking into account your diesel costs and installation costs and all of that?”Esterhuysen: “We’re doing very well in terms of managing our costs especially considering the excessive amount of loadsheddingwe’ve had this year. At Qwaqwa campus, on top of loadshedding, we also get load reduction. The municipality overloads the Eskom infrastructure and they just cut us off. We had a period last year of six days without power. And this year we had a period of two and a half days without power. In these extreme cases, especially, it was worth the money, and the effort.”
8. Mr Mpho Kau, Interim Senior Director: Operations at the Mangosuthu University of Technology: “I see the university has opted not to have a battery backup. Is there any reason for that? I got a sense, in previous presentations, that hybrid systems include some battery backup.”Esterhuysen: “Battery backup is part of our Phase Two planning. But their application needs to be carefully defined. The biggest consideration to provide battery backup for the entire system was the initial cost. It was just too expensive for this campus size.”
9. Gobardan: “With the scale of your grid you are obviously exposed to crime. How have you made sure you safeguard the investment?”Esterhuysen: “At QwaQwa, it is fenced off — a clear fence, with an electric fence on top. And it is inside the campus. We have a high mast light and about seven CCTV cameras covering the entire area. The other solar plants have cable fencing with electric fencing, and alarms. In five years, we’ve only had one attempted theft and that was on our experimental farm which has a smaller installation.”
10. Gobardan: “Some universities may not be as cash flush to go with such extravagant plans. What advice do you have for them? What quick wins can they consider in the short term to mitigate the loadshedding challenge?”Esterhuysen: “First of all, I would look at energy efficient technology. And a PPA for universities that don’t have the technical skills can be a good option. At our Bloemfontein campus, we have a distributed approach to our diesel generators, not a centralised one, and that could be implemented much quicker and target critical areas more effectively. Look at options for solar and battery storage. That is what we are doing in Qwaqwa, where our new student centre will be ‘almost’ off grid – I think you can never say ‘fully off grid’.  So, target specific buildings.”

Gillian Anstey is a contract writer for Universities South Africa. 

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