Solar electricity from rooftop: The way to go

To quickly increase solar electricity production, all underutilized or unused land/spaces need to be utilized properly

Global concern regarding temperature rise due to man-made greenhouse effect has pushed all countries around the globe to invest in electricity generation using renewable energy technologies. Our country has also targeted to boost its production capacity to 24,000 MW by 2021, about 10% of which will come from renewable energy resources although the number is sitting at 2.83% at present. The commitment of our government is also reflected in the recently released mega plan - 60,000 MW by 2041 with a significant portion from renewable energy resources. A colossal question then pops up – how can we achieve this goal?

Of many types of renewable energy resources, solar, wind, and hydro energies are mostly used for the generation of utility-scale electricity. Except for Kaptai plant in Rangamati, there are no known resources for hydroelectricity generation in our country. Harnessing wind energy is limited to coastal areas, and a huge initial investment will be needed to harness our capability not for installing wind turbines but for building the infrastructure for the transmission of electricity. The only way we can significantly ramp up our share of electricity generation from renewable energy resources is by using photovoltaic – generation of electricity using sunlight - technology in an efficient way.

In our country, we have already got installed 4.5 million home solar systems that have significantly changed the energy landscape in the remote areas of our country, but these are mainly off-grid or standalone system with no contribution to the national grid. An estimate by Sustainable and Renewable Energy Agency (SREDA) shows that solar electricity feeding to the national grid stands at meager 0.07%, which is undoubtedly a non-significant number. Efforts must be taken to improve this scenario by all possible means.  The best way to ramp up electricity generation is to build solar farms and feed power directly to the grid. Apart from the cost of photovoltaic module, accessories, and installation, the big hurdle is to get a suitable piece of land for the utility-scale generation. With a population of about 170 million, our arable land, accounting for 16% of country’s gross-domestic-product (GDP) and employing 47% of the workforce, is getting slowly but continuously swallowed by the rural housing, urbanization, and industrialization. If the land-loss continues to happen at the current rate, the amount of cultivable land will shrink considerably in the near future. It will push our food security at stake, thus making the mass population immensely vulnerable to commodity price in the world market. Everybody will agree that nothing could be more catastrophic than this for a nation of 170 million people.

Unlike many countries, there is no desert or a huge amount of barren, unused land in our country. Conservative estimate shows that setting up a solar farm of 1 MWdc capacity requires about 2.5 acres of land just for the installation of solar panels. Also, spaces are needed for access roads, substation, control and service room for inverter and monitoring system, which leads to the fact that the minimum area required – called direct area - is at least 3.0 acres.  A study by National Renewable Energy Research Laboratory (NREL), the USA on all utility-scale ground-mounted solar farms (fixed mount) shows that the total land requirement- all land enclosed by site boundary- is on average 40% greater than the direct area. It means that it requires at least four acres of land to have a solar farm of 1 MWp, which supplies about 800 kWac electricity to the grid.

Keeping the above number in mind, let’s do some quick calculation. Any cultivable land in our country produces at least two crops a year, and the case of paddy producing fields can be taken into consideration since rice is our staple food. Data shows that one acre of land produces about 2,640kg to 4,050kg of paddy depending on the variety of paddy, with an average yield of 3,345 kg/acre. Four acres of land will, therefore, produce 26,760 kg of paddy, which in turn will produce 17,395 kg of rice every year. This amount of rice is good for feeding 11,600 families a day (1.5 kg/day) or 32 families for a whole year.  To install a 100 MWp solar farm, the total land requirement will be about 400acres that is good enough to feed 3200 families for the lifetime of the solar farm, which is at least 25 years.

However, the following issues must be kept in mind before using any land – even the barren ones - for solar farm installation. Firstly, it has to be made sure that no high-rise structure will be built around the periphery of the boundary during the tenure of the project. Secondly, the population in our country is projected to grow to 202 million by 2050. Thirdly, the capacity factor, a measure to calculate the efficiency of a power generation station, for photovoltaic systems is on average lower than other renewable as well as non-renewable energy systems. The last, not the least important point refers to the fact that acquiring land for industrialization generates job which is good for our economy, social stability, and growth since it is labor intensive, but a solar farm does not create any significant long-term employment opportunities after being installed once. To the best of my knowledge, there is a policy in place not to use the cultivable land for energy harvesting, and under no circumstances, it should be compromised. Moreover, the time has come to strongly think whether we can afford to use even our barren land for solar farming.

Although the price of solar panels has decreased significantly in the last five years, it is still a fact that without any incentive, it is not lucrative or comparable, as far as the financials are concerned, with the generation of electricity by other means, such as fossil fuel. In our country, lands are costly mainly due to its fertile nature and demand to meet the need of the growing population.  If a piece of land is available close to the transmission line, the additional cost for building the infrastructure for electricity transmission will decrease. On the other hand, if a remote location is chosen, the cost of land will go down, but the cost for building electricity transmission infrastructure will go up. A simple model by taking into account all these factors show that the price per watt-peak of solar installation may go up from 10 Tk to 40 Tk just to meet the cost of land and transmission line.   It means that for a 1 MWp solar farm the initial cost of solar electricity generation will go up from one crore to four crores. For 100 MWp solar farm installation, the price will be an additional 100 crores to 400 crores,  a whopping amount      for a country like us. Now, the question comes in: could we harness solar energy to supply electricity to the grid in a cost-effective way?

To quickly increase solar electricity production, all underutilized or unused land/spaces need to be utilized properly. In large cities, population density is much higher than countrywide average, and there exists a huge number of high-rise buildings in all major cities, and that, the numbers are growing rapidly to ensure housing for the mass population. The top of these buildings – generally called ‘rooftop’ – gets enough sunshine throughout the whole day and are a good place for harvesting solar energy. Using these areas will set up a network of distributed generation that will make use of existing transmission capability. That will not only significantly reduce the cost of initial investment of the government but also decrease the loss of power for transmission. Public buildings are accessible to the government, and the plan can be implemented very easily.  Moreover, there must be a policy in place so that homeowners will be willing to install solar panels on their roof, and that they will be paid for every unit of generated electricity. The policy must be lucrative enough to make people involved in the program by ensuring a stable income for the next 25 years.

For the policy to be lucrative, the government must make sure that the payment is hassle free with a minimum payback time – the time required to recover the cost of the initial investment. There are many successful programs of this type running across the globe, and it is necessary to learn from their experiences to optimize a plan suitable for our country.  

The writer is Associate Professor,

 North South University

 

Solar electricity from rooftop: The way to go

To quickly increase solar electricity production, all underutilized or unused land/spaces need to be utilized properly

Global concern regarding temperature rise due to man-made greenhouse effect has pushed all countries around the globe to invest in electricity generation using renewable energy technologies. Our country has also targeted to boost its production capacity to 24,000 MW by 2021, about 10% of which will come from renewable energy resources although the number is sitting at 2.83% at present. The commitment of our government is also reflected in the recently released mega plan - 60,000 MW by 2041 with a significant portion from renewable energy resources. A colossal question then pops up how can we achieve this goal? Of many types of renewable energy resources, solar, wind, and hydro energies are mostly used for the generation of utility-scale electricity. Except for Kaptai plant in Rangamati, there are no known resources for hydroelectricity generation in our country. Harnessing wind energy is limited to coastal areas, and a huge initial investment will be needed to harness our capability not for installing wind turbines but for building the infrastructure for the transmission of electricity. The only way we can significantly ramp up our share of electricity generation from renewable energy resources is by using photovoltaic generation of electricity using sunlight - technology in an efficient way. In our country, we have already got installed 4.5 million home solar systems that have significantly changed the energy landscape in the remote areas of our country, but these are mainly off-grid or standalone system with no contribution to the national grid. An estimate by Sustainable and Renewable Energy Agency (SREDA) shows that solar electricity feeding to the national grid stands at meager 0.07%, which is undoubtedly a non-significant number. Efforts must be taken to improve this scenario by all possible means. The best way to ramp up electricity generation is to build solar farms and feed power directly to the grid. Apart from the cost of photovoltaic module, accessories, and installation, the big hurdle is to get a suitable piece of land for the utility-scale generation. With a population of about 170 million, our arable land, accounting for 16% of countrys gross-domestic-product (GDP) and employing 47% of the workforce, is getting slowly but continuously swallowed by the rural housing, urbanization, and industrialization. If the land-loss continues to happen at the current rate, the amount of cultivable land will shrink considerably in the near future. It will push our food security at stake, thus making the mass population immensely vulnerable to commodity price in the world market. Everybody will agree that nothing could be more catastrophic than this for a nation of 170 million people. Unlike many countries, there is no desert or a huge amount of barren, unused land in our country. Conservative estimate shows that setting up a solar farm of 1 MWdc capacity requires about 2.5 acres of land just for the installation of solar panels. Also, spaces are needed for access roads, substation, control and service room for inverter and monitoring system, which leads to the fact that the minimum area required called direct area - is at least 3.0 acres. A study by National Renewable Energy Research Laboratory (NREL), the USA on all utility-scale ground-mounted solar farms (fixed mount) shows that the total land requirement- all land enclosed by site boundary- is on average 40% greater than the direct area. It means that it requires at least four acres of land to have a solar farm of 1 MWp, which supplies about 800 kWac electricity to the grid. Keeping the above number in mind, lets do some quick calculation. Any cultivable land in our country produces at least two crops a year, and the case of paddy producing fields can be taken into consideration since rice is our staple food. Data shows that one acre of land produces about 2,640kg to 4,050kg of paddy depending on the variety of paddy, with an average yield of 3,345 kg/acre. Four acres of land will, therefore, produce 26,760 kg of paddy, which in turn will produce 17,395 kg of rice every year. This amount of rice is good for feeding 11,600 families a day (1.5 kg/day) or 32 families for a whole year. To install a 100 MWp solar farm, the total land requirement will be about 400acres that is good enough to feed 3200 families for the lifetime of the solar farm, which is at least 25 years. However, the following issues must be kept in mind before using any land even the barren ones - for solar farm installation. Firstly, it has to be made sure that no high-rise structure will be built around the periphery of the boundary during the tenure of the project. Secondly, the population in our country is projected to grow to 202 million by 2050. Thirdly, the capacity factor, a measure to calculate the efficiency of a power generation station, for photovoltaic systems is on average lower than other renewable as well as non-renewable energy systems. The last, not the least important point refers to the fact that acquiring land for industrialization generates job which is good for our economy, social stability, and growth since it is labor intensive, but a solar farm does not create any significant long-term employment opportunities after being installed once. To the best of my knowledge, there is a policy in place not to use the cultivable land for energy harvesting, and under no circumstances, it should be compromised. Moreover, the time has come to strongly think whether we can afford to use even our barren land for solar farming. Although the price of solar panels has decreased significantly in the last five years, it is still a fact that without any incentive, it is not lucrative or comparable, as far as the financials are concerned, with the generation of electricity by other means, such as fossil fuel. In our country, lands are costly mainly due to its fertile nature and demand to meet the need of the growing population. If a piece of land is available close to the transmission line, the additional cost for building the infrastructure for electricity transmission will decrease. On the other hand, if a remote location is chosen, the cost of land will go down, but the cost for building electricity transmission infrastructure will go up. A simple model by taking into account all these factors show that the price per watt-peak of solar installation may go up from 10 Tk to 40 Tk just to meet the cost of land and transmission line. It means that for a 1 MWp solar farm the initial cost of solar electricity generation will go up from one crore to four crores. For 100 MWp solar farm installation, the price will be an additional 100 crores to 400 crores, a whopping amount for a country like us. Now, the question comes in: could we harness solar energy to supply electricity to the grid in a cost-effective way? To quickly increase solar electricity production, all underutilized or unused land/spaces need to be utilized properly. In large cities, population density is much higher than countrywide average, and there exists a huge number of high-rise buildings in all major cities, and that, the numbers are growing rapidly to ensure housing for the mass population. The top of these buildings generally called rooftop gets enough sunshine throughout the whole day and are a good place for harvesting solar energy. Using these areas will set up a network of distributed generation that will make use of existing transmission capability. That will not only significantly reduce the cost of initial investment of the government but also decrease the loss of power for transmission. Public buildings are accessible to the government, and the plan can be implemented very easily. Moreover, there must be a policy in place so that homeowners will be willing to install solar panels on their roof, and that they will be paid for every unit of generated electricity. The policy must be lucrative enough to make people involved in the program by ensuring a stable income for the next 25 years. For the policy to be lucrative, the government must make sure that the payment is hassle free with a minimum payback time the time required to recover the cost of the initial investment. There are many successful programs of this type running across the globe, and it is necessary to learn from their experiences to optimize a plan suitable for our country. The writer is Associate Professor, North South University