Heating and cooling form an important part of the energy ecosystem but are responsible for a significant amount of carbon emissions.

PEI’s Pamela Largue spoke to Kingston University renewable energy expert Dr Hasan Baig about how heating and cooling impact the energy transition, as well as the importance of efficient solar usage in reaching electrification goals while reducing emissions.

Tell us more about your research on solar efficiency? 

I have been working in the area of renewable technologies since 2008, where I started my career at a research center based in Saudi Arabia.

After pursuing a PhD in building integrated solar technologies in the UK, I created a company called Build Solar Limited, which develops solar technologies within building materials.

I have been simultaneously working on several research projects, looking into where we can utilize solar heat, which is where this particular work comes into the picture.

After visiting a renowned institute in India I began brainstorming a concept to extract as much energy as possible.

As you might be aware, typical solar technologies are roughly 20% efficient. Whereas almost 80% of the energy that is coming from the Sun is lost or dissipated in the form of heat.

I was looking for ways in which to capture that heat and perhaps make better use of this heat, in some applications.

We singled out an application related to refrigeration and cooling, crucial in countries like India. We investigated how to generate electricity from our solar panels, while extracting and capturing excess heat, which was otherwise being lost, and using it for heating and cooling purposes.

How about your solar research, methodology and results?

As you may know, the blue colour silicon solar panels that are commonly available have a limited percentage of efficiency, only able to harness 20% of the available solar energy. The rest is dissipated in the form of heat.

A simple way to capture that heat is to add a heat exchanger behind the panels.

Think of it as a few tubes that carry a coolant or a liquid behind the panel and as the water or the coolant passes through it, it helps cool down the solar cells and extract out the excess heat.

During this process, the temperature of the water or the coolant, which is behind the solar cell, is limited to the solar intensity that is available to you, roughly a maximum of about 30-40 degrees centigrade.

A simple way to use that is to couple it with our existing water heating systems causing our heaters to be more energy efficient.

Read more Removing solar panel hotspots boosts electrical and thermal output- study

So, we have a certain amount of hot water available behind the PV panel, however, we wanted to further research how to increase this temperature.

A simple way is to concentrate the sunlight. We used mirrors and concentrated the amount of sunlight falling on the solar cells or PV panels. By increasing the amount of sunlight falling on the PV, it essentially doubled the amount of electricity production with the same efficiency. The more solar concentration led to greater radiation and double the output.

The increased radiation allowed for a higher temperature of water to be extracted from this hybrid PV thermal system. That high-temperature water or cooling fluid could be utilized for refrigeration and air conditioning cycles more effectively. In our case, we used an air conditioning cycle for which having a temperature of roughly 50 – 60 degrees is perfect. It seamlessly integrates with that refrigeration cycle.

In countries like India, this is particularly applicable for cooling and refrigeration, which can be very expensive and energy-intensive.

However, during this stage, we found that because of the use of the mirrors, the solar radiation is concentrated, but not in a uniform manner. There are places on the PV panel that become very hot, and other places that might not be that hot. We call these variations hotspots on the PV panel.

To mitigate those hotspots, we employ something called a homogeniser, which essentially cuts down the non-uniformity on the PV panel.

This was an important phase of the research. We found that because of these hotspots, there was a difference in the amount of current generated across the PV panel.

The net output is determined by the lowest number rather than the highest number of current because they are all connected in series.

Have you read? Managing the impact of resource variability on solar asset performance

Once we evened out the solar radiation, we evened out the amount of current that was being generated in these individual solar cells, which improved the electrical performance and reliability of the PV panel.

The whole objective of the study is to work towards the global mission of generating more power at less cost.

The fact is we could have simply added a couple more solar panels to the same refrigerant and air cooling cycle. However, the cost of doing that, compared to what we had proposed, was roughly three to four times more. This makes a big difference in poorer countries that are trying to increase penetration of green energy technologies.

This gave us the opportunity to generate energy more efficiently at a much better cost.

How are you planning to use the results of your research?

One of the consequences of this work was that we partnered with a commercial company in India to trial this technology. In this way, the research has taken a step forward allowing us to really test the technology in a real environment.

Hopefully, this can lead to the creation of a new company and the development of products that will be valuable to countries with highly cost-competitive landscapes.

What are your future research plans?

This study allowed us to make an effective numerical model, which can evaluate the performance of this kind of technology or similar technologies in a wide range of environmental conditions.

Because of the work done to develop this model, we now have the option to look into further improvising heat extraction.

We can now study different kinds of heat exchangers based on this original design, consider how we could manufacture these heat exchangers in a cost-effective manner, and investigate new techniques of additive manufacturing in order to prototype and study these. There is still a great deal of work to be done.

Dr Baig is an energy engineer with over 12 years of experience in developing several low carbon technologies, setting up a state-of-the-art solar laboratory, teaching engineering courses and supervising students.

He spearheaded several UKRI & Innovate UK projects under interdisciplinary settings, provided technical leadership, written grant proposals, and carried out wider engagement with several national and international universities/industries. Currently, he works as an assistant professor/ lecturer in renewable energy at Kingston University where he teaches and leads the activity of research and development of renewable energy technologies.

Learn more about Dr Baig and his work at Kingston University.

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