|
|
1. Towards a Solar-Powered Era
Charles Iskander Yousif
Malta’s most prominent indigenous renewable energy resource has been known for decades to be solar energy, which also includes wind energy. Yet so far, little use has been made of this resource except for sun-tanning and a limited number of wind mills. The question keeps repeating itself: “But Why hasn’t Malta yet reaped the benefits of solar technology?” The answer actually lies in another question: “But how much do we actually believe in it?”
In this article, an attempt will be made to put some more confidence in the potential lying in at least one form of solar energy, based on real-life experience in the conversion of solar light to electricity. A solar photovoltaic system mainly comprises of solar cells, which convert light energy to electricity that can be stored in batteries or fed into the grid through an inverter. The generated electricity could be used immediately or exported to the grid. In both cases, this would contribute towards lowering the electricity bill of the consumer.
By placing solar systems on rooftops, one avoids the use of land that is scarce and expensive in Malta. Moreover, the roofs in Malta are flat, which implies that the solar modules can be placed in such a way as to maximize their output.
Photovoltaic applications in Malta that were so far restricted to research and demonstration systems will soon be available for everyone to install, according to the regulations to be set by the Malta Resources Authority. Besides the demonstration projects, there are so far only two privately owned solar grid-connected systems in Malta, one at a residence in Madliena operating since May 2002 and another one in a Marsa factory, installed in September 2002.
Three different solar systems are also in operation at the Institute for Energy Technology. The oldest grid-connected photovoltaic system in Malta is the 1.8 kWp stationary plant installed on the Institute’s rooftop in Marsaxlokk. During the past six years, the system produced over 10,000 units of electricity, which reduced the Institute’s electricity bill by 60%. (This is roughly equivalent to two and a half years of electric consumption of a home housing four persons). This amount of free solar electricity has also avoided burning 1,100 gallons of fuel oil at the power station, to produce an equivalent amount of electricity for end-use. Moreover, it has saved the environment 13 tonnes of carbon dioxide, 260 kg of sulphur oxides, 16.2 kg of nitrogen oxides and 5 kg of particulate matter.
As time passes by, an increasing number of multi-level buildings are replacing the older traditional two-storey terraced houses, due to space limitations, high land cost and greater demand for smaller dwellings. In turn, less roof area per household would be available for installing solar systems. Moreover, the older buildings that may be adjacent to these high-rise constructions would have less effective sunny areas on their roofs due to shading. In such cases, solar tracking may be attractive since it would maximize on the production of energy from solar radiation in a limited space. Moreover, one can produce enough electric power with less number of solar modules and lower capital costs. Solar tracking operates best under clear sky conditions, and this matches the weather conditions in Malta where rainfall is minimal. Another advantage of tracking systems is that since only few solar modules are installed on one tracker, a system of trackers can be easily distributed independently in the sunny areas of the roof.
The second system at the Institute comprises of six solar modules that are mounted on a tracking device and connected to the grid through an inverter. This system has so far produced 1,500 kWh. It has intercepted 20% more solar radiation than the stationary system per unit area and produced 60% higher final yield per installed Watt of PV module. Its efficiency was also 40% greater than the stationary system. This implies that in order to produce a certain amount of electric energy, up to 40% less roof area would be needed. When comparing between two systems having equal output energies, the tracking system would have a 20% lower capital cost than a stationary one. The ongoing research will further be used to confirm these results on a long-term basis.
The third solar system that was installed few weeks ago will study the performance of the state of the art palm-sized inverters (shown in photo), which is the future of photovoltaics in the world. Ideally, a solar module would produce a.c. power to match our everyday needs. This small inverter makes this a reality, so much that the solar panels can now be termed as “a.c. modules”. The flexibility that such an inverter gives to a solar system makes it ideal to take full advantage of each and every corner or space where the sun shines. By employing a.c. modules, architects can literally make use of single solar modules to match their design needs. Most importantly, such an inverter will eliminate the need for checking on mismatching of modules or partial shadowing of system. It would now become easy to choose different module sizes and colours and blend them into a single architectural work piece, with no negative impact on system performance.
Besides the technical studies, the widespread applications of solar photovoltaic systems require an analysis of the economic and social viability, as well as an energy dissemination plan that will implement incentives to accelerate the use of such technologies in Malta, both now and in the future.
Hence, periodical studies are being carried out to analyse the life cycle costing of different photovoltaic grid connected systems for residential and commercial buildings and to correlate the system size with the electricity price, the payback period and the required rooftop areas. Charts are produced to help predict future costs of different systems and to provide answers to frequently asked questions. A proposal has also been made for introducing regulations and guidelines for grid-connection. Such a move would be necessary before grid-connection becomes widespread in Malta.
Photovoltaic Applications, feasible by the year 2010:
Some of the results obtained indicate that solar electric systems could be economically feasible, when installed in the year 2010 and beyond. As the size of the system grows, the payback period decreases due to economies of scale. It is worth noticing that while amorphous thin-film cells tend to pay back faster, their lifetime is only about 60% of that of crystalline silicon cells. This implies that even though the initial price for a thin-film system could be lower, the net profit at the end of the system life would be lower. More importantly, this means that unless the present technology of amorphous silicon advances dramatically, it will not be able to compete with the traditional crystalline silicon cells.
Though photovoltaics may not currently have a good payback period, this does not imply that they should not be implemented today. PV works without need for maintenance and regardless of the economic effects. It is a viable energy supplement that is being widely used all over the world. Additionally, if one looks around, one would realize that everyday we spend on items that are not economically viable, but that does not make them any less of a necessity or prevent us from purchasing them. It is not fair that we think of payback periods only when it comes to purchasing solar systems that after all do not pollute the environment, nor require fuel or maintenance.
Not withstanding that, photovoltaic applications are economically feasible even today especially if they are included in the initial design stages of a new building. Solar panels can replace traditional building materials and come in different colours and shapes.
As for home users, a solar system need not be so large as to offset 100% of the electricity needs. The smallest system could cost as little as Lm500. Solar systems are modular which allows for more modules to be added at a later stage. One possible option for installing home solar systems today is to match the size of the solar system in such a way that it alleviates the electricity consumed at the higher charge rate of electricity. In this way, there will be no need for installing large systems from the start. Naturally, the optimum size of the system will have to be determined on a case-by-case basis, as each household has different electric consumption rate, available roof area, orientation and budget.
What About the Power Stations?
There are three important points that need to be raised on the side of oil fired power plants.
Rooftop decentralised photovoltaic systems as opposed to large photovoltaic plants have the advantage of reducing power variations at the power plants, which may be caused by overcast skies. A passing cloud over parts of the island would only affect that portion of the island while the other more sunny regions would continue to produce power in the meantime.
2. There will be no loss of jobs at the power stations due to the implementation of solar energy. The addition of PV cells on rooftops would only account for a maximum of about 15% of the overall electricity generation due to limited areas of rooftops available. On the contrary, Enemalta would have the extra job of certifying and networking these systems to its grid. Anyway, it would also take many years of hard work and intensive programmes to install solar electric systems on all rooftops!!!!
3. Using photovoltaics reduces peak loads caused by air-conditioning during summer, thus helping to relieve the load on the power station and improve the power factor of the grid.
Why Should People Change?
There is an urgency to shift to a “solar culture”. The international market of oil is very unstable due to price changes and political considerations. This possibility alone should make the use of renewable energy applications a necessity, thus shifting the economic feasibility to a lower level of importance.
Malta depends completely on the importation of fossil fuels for its energy needs. The hard currency is mainly obtained from the tourist and export industries. In the event that these two industries face difficulties, oil imports would only increase the national debt. We have to build renewable energy systems especially solar and wind energy systems now, before we learn the hard way.
In the case of home-owners, a solar photovoltaic system that could supply more than 50% of the electricity needs of a family of four would cost Lm 3,000 today and would occupy 10 m˛ of roof area. One has to emphasize that solar systems can be trendy, add value to the property and are long lasting. It also encourages energy conservation since each individual would be involved in the production process of electricity and will tend to save as much as possible so as to reduce the electricity bill.
It is worth mentioning that in order to promote the use of photovoltaic systems, a promotion for solar water heaters becomes a necessity. It is five times more efficient to heat water by means of a solar heater rather than using a solar electric system. Although the prices of solar heaters have dropped considerably, they are not as popular as one would expect, and this brings in the role of advertising, which so far has concentrated only on savings on the electricity bill. Solar heating systems provide security to the supply of hot water and have to be considered as necessary to everyday living. Government incentives might help to promote them but it will not be enough until everyone agrees that the answer to the key question is a YES; that we believe in solar technology.
Eng. Charles Yousif is a researcher working on solar photovoltaics since 1992, at the Institute for Energy Technology. E-mail: charles.yousif@um.edu.mt. Mr. Yousif is the Secretary General of the Malta Energy Efficiency and Renewable Energies Association (M.E.E.R.E.A.).
Back to My Articles
Back to Institute's Articles
|
