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Solar energy and applications

svein_gaute@opensky


In our previous article on energy and the climate we commented on climate change and how important the use, management and consumption of energy are in this context – and that there is a need for an energy transition. We also commented on some challenges of energy supply. This article is the second of three, elaborating specifically on solar energy. The joint goal of the three articles is to enhance the awareness of the energy situation today, how energy may influence emissions and improve daily lives and business, to look into some of the related challenges and solutions - and the fact that we all have a role to play in order to take responsibility for speeding up the required energy transition in the world.


Solar Energy potential


The beauty of Solar is that this form of energy from the rays of this source is of practically endless capacity and very easy to capture when available during daylight, and strongest at cloudless or minimal clouds in the sky. The sunbeams are also locally available at every position on the globe, though variable by latitude, enabling capture of energy next to the consuming place, without loss in energy transport from centralized power utilities. Hence truly short-travelled energy from production to consumption may be achieved.


Some 23.000 TW hits the surface of the earth yearly. In comparison, the total available power from existing coal sources globally is only 900 TW – but for “one time use” only. This means that solar energy may be captured in every corner of the globe, in the most distant and rural areas of the world, and to a very large degree along the equator belt where sun is very much available. We may say that solar energy potential can be defined as the physically available solar radiation on the surface of the earth.


However, should deserts like the North African Sahara be transformed into a giant solar farm, this would not only cover the entire world’s current energy demand, but 85% of the energy hitting the black solar panel surfaces would be returned as heat to the environment, as only the 15% remaining fraction will be converted into electricity. Heat re-emitted from an area this size would be redistributed by the flow of air in the atmosphere, having regional and even global effects on the climate. Hence, this phenomenon should be carefully observed as the global PV-based (Photovoltaic) volumes grow in the future.


In a not-too-distant future, other solutions to capture the energy of the sunrays may appear as well. In fact, a facility for extracting energy from the sun was last May placed in space and located in orbit 36,000 kilometers from Earth. Now the main challenge that remains is to find a method to bring the energy down to earth at any desired location. Then you may have a global transmission of energy to even the most remote places on earth, a great advantage compared to any other source of energy – a new energy revolution which finally may cover our entire globe, enabled from the Sun and solar power?


The technology used is a solar panel with a diameter of only 30 cm, a Photovoltaic Radiofrequency Antenna Module (PRAM), is able to capture lots of energy in the form of blue light, which has a short wavelength and is reflected in all directions in the atmosphere. A 10 W production has already been achieved from the PRAM, and the methods proposed for transmission to earth are either in the form of microwaves or with a huge laser. Researchers believe that the solution could deliver the same amount of power as our largest power plants, several gigawatts. Until this happens, let us stick with what is available.


Solar deployment


Solar panels may be installed on buildings, most commonly on rooftops but also wall panels can be used. Solar tiles, which may give an improved aesthetic impression holds solar cells integrated directly on the tile surface, but their price is higher and energy production per m2 is lower than for panels – and panels may also easier be replaced in the future as technology advances. In cases of limited building space panels may be erected on water, farmland, wasteland or productive soil – and in the latter case, when carefully installed considering location, height and angle, will allow for continued agriculture production or as land for livestock. There are multiple examples of successful co-existence between solar installations and productive farmland - in fact the mix of solar and shade can even improve agriculture production results.


Solar technology can bring energy and electricity to remote places in all corners of the globe, in particular to areas not yet served by the grid. PV-installation can be pretty easily deployed in on- or off-grid configurations. Large solar-based systems may be deployed in plants and parks, grounded or onto buildings where panels do not occupy any add-on footprint to valuable land and property. Maybe in urban areas the future will provide sidewalks covered with solar tiles picking up energy from the sunrays and also movement energy from the pedestrians? Technology and solutions for the latter is already produced, a real negative footprint device (no comment on economic viability though).


Solar technology, development and role


Solar will contribute not only to the energy transition from fossil to renewable energy but is also a most important energy source to cater for predicted growth in coming decades towards 2050. Solar PV is today a mature technology and Silicon cell technology is being rolled out in large volumes. However, this does not imply that new and improved technologies will not soon take their positions in this market – like e.g. Perovskite thin-film and/or panels with mix of Silicon and Perovskite. Research and enhancements of Solar technology will certainly continue in years to come.


New thin-film products are expected to open for use on curved surfaces not easily covered today, as well as solutions that open for solar cells on window glasses, motorized vehicles, boats and planes. Bi-facial panels are typically usable in ground applications for agriphotovoltaic (APV) projects (PV on farmland) or combined as fence alongside motorways etc. Increasing the transparency in these solar cells for the use on window glass, makes the efficiency drop down rapidly though. Hence, the fully transparent solar cell is not yet commercially available in the solar market. Panels mounted for automatic motorized tilting, allowing the solar cell’s surface to follow the angle and direction of sunrays to obtain maximum radiation throughout the daytime, are also available, though this increases price level and imposes the need of regular maintenance.


Today’s silicon-based panels hold typical efficiencies up to 20%, whilst lab tests with prototyping of perovskite alone or in hybrid with other materials are reported to reach up to 30% and expected to reach even above 32%. Various types of roof tile combined solar cells are promoted as alternatives if aesthetics, architecture and visual preference are prioritized. It should be expected that scientists and researchers will provide even better efficiency, stability and durability in the coming future – though perhaps marginal to already reported achievements. Awaiting these enhancements only to gain maximum effect of a new PV-system is probably not economical, as you then loose own energy production in this period and have to pay the utility companies for the energy supply. A net present value NPV exercise covering all factors is thus recommended.


Solar-system configuration, investment and use


In order to gain maximum effect of solar panels it is important to gain the optimal positioning for the photons of the sunrays to hit the solar cell surface. Thorough studies must be made for placement of panels to obtain potential of reflections from water, ice and snow effects. Bi-facial panels may be used on ground and positioned to obtain maximum reflections to back sides. Similarly, bi-facials may be mounted on flat roofs, especially favorable on asphalt roof membrane specifically designed with high Albedo effect. Isola products have obtained some 60% reflection of sunrays hitting the membrane.


For buildings it is easier to plan for solar cells on new rather than old buildings or renovation candidates, whilst for APV, i.e. use on farmland, operational considerations must be taken. Shadowing from trees and new buildings in urban areas may also impose future shadowing effects. An introduction to solar energy and practical use cases can be studied here - and a tool for calculation of a PV-system at particular addresses (in Norway) can be found here (in Norwegian).


Solar PV systems are regarded a financially sound investment which pay off with an RoI within a period of 10-12 years in most cases. You could argue that your energy consumption is then free of charge for a few decades, as there is a 25 years’ warranty for panels and expected lifetime of 35 years+, but development of new technology may tempt the owner to make replacement before the panel’s end of life, and the inverter functionality is expected to cater for new functionalities which may be found viable to replace as well, prior to its expected end of life of 12-15 years.


Further development of the functionality and performance of Solar PV systems is continuously ongoing, and enhancements for enterprise and private markets will focus on optimization of energy production volumes and cost per kWh. Hence systems for energy management are already in the market, allowing users to reduce and move their peak consumption to low-cost periods for their utility supply. Actually, energy optimization will be equally important for producers as for consumers in the new prosumer market.


Solar tech development


In the near future, solar cells based on thin-film perovskite technology may cover walls and other vertical surfaces of buildings, even window glassing. Introduction of Perovskite may disrupt the market and lead to price reduction of solar technology by 80% and an increase in energy of 30% versus what a silicon solar cell can produce. By 2030 perovskite is estimated to take up to 30% of the market. Between 2009 and 2015, solar PV module prices fell by 80%, ushering in a new era of affordability not only for the developing markets, but also made solar energy more attractive in the industrialized world.


From a user perspective, business or private, there are new solutions which may be considered attractive to implement as well. With the growing EV base in all markets, the possibility of bidirectional charging and use of EV batteries for V2B/V2G (Vehicle to Building/ Vehicle to Grid) will introduce flexibility in power supply and smoothening of the user’s peak consumption from the grid. Even a DC/DC option for PV to EV or stationary batteries may be considered a favorable option, providing some 20% more efficiency to the system as conversion of AC/DC current will then be avoided. The same advantage may also be achieved if multiple buildings equipped with solar panels are interconnected on DC/DC cabling.


Some markets experience from time-to-time power outages, caused by natural catastrophes and extreme weather or even deliberate periodical shutdown of supply from utilities, often in developing countries, due to grid limitations. Also, in case of social unrest which may occur from terror, severe pandemics or similar events, this may lead to interruption of power supply from the grid. Hence possessing your own power supply from hybrid PV/EV/battery systems to cater for the most basic needs, whether in offices or homes, may be regarded a desired asset. A smart home observation and optimization system will be an additional economical asset. Note though due to health and safety for O&M personnel, PV-load may not be put on the grid in case of outage, yet.


When investing in a PV-system for private or enterprise use, enhancements of the system and implementation of energy optimization management applications should be considered. Also, even for a system lifetime of 35 years+, a replacement of inverters every 12-15 years and decommissioning of panels by end of life should be considered - even for upgrades of esthetic or performance considerations due to technology advancement. Most importantly, however, optimal sizing of the system should be done from day one, with careful planning and implementation by certified personnel – providing certificate of completion, system performance and electro fire-safe installation.


Local Energy Communities


Introduction of renewable energy enables establishment of local energy communities, which collaborate to produce and consume renewable energy locally in a structured and geographically limited area. This concept may vary between neighborhoods in small communities to larger projects where private, co-owners, farmers, industry, external players and entrepreneurs in collaboration with grid companies establish local energy communities. These can be established in rural and peripheral areas, but also in districts of more central residential/industrial areas. However, to enjoy optimal functionality and financial benefits for all players, good interaction on planning and operation is required, so that benefits for the community do not lead to rising prices for remaining grid customers, which has been the case with higher grid tariffs in areas with high customer connectivity based on renewable energy.


Such energy communities are usually based on wind turbines and, in particular, photovoltaic systems as the most common production units. In addition, hydropower, bioenergy plants and diesel generators are used for power production, as well as stationary batteries and electric cars for energy storage. For optimal energy production with the transfer of surplus energy to the connected main grid and consumption of self-production in the energy society, good control systems will be absolutely required. There could be more environmental benefits if such local energy production is introduced to replace expansion and new deployment of infrastructure, as the solution could reduce the utility-grid loads during periods when consumption is high, and during periods of high production. In addition, transmission losses in the main grid are reduced.


Grid regulations and planning


National Regulators and/or utilities may put restrictions on how much energy is allowed to send to a connected grid network. In my country Norway this is normally 100 kW peak power, as beyond this a public license is required. It is obvious that introduction of a new situation following multiple renewable energy producers, from multiple farmers, private houseowners, apartment/commercial buildings, real estate large and small, will change the amount and flow of energy in the network grid, and brings challenges in terms of forecasting and building network capacity and structure. In any case, national regulations probably need an overhaul.

In addition to the entry of Solar PV to private and commercial buildings, EV batteries and stationary batteries in buildings will soon pose multiple sources of power generation for local consumption and surplus production offerings to the network grid, making a need for balancing network load and consumption. Planning and maintenance of the future grid will be a complex exercise, however, with multiple factors being constantly added and consumers changing behavior, hence careful collection and analyses of power data from various sources and sophisticated software tools for planning is required.


Mini- and Micro-Grid (off-/on-grid) solutions


Received and converted solar energy may be brought to the doorstep of individuals and businesses in the 3rd world, with limited means of hardware, marginal deployment efforts - and in hybrid solutions with other renewables like biogas-based generators, turbines for wind power and battery back-up. Limited investments are required for in mini-grid renewables that may bring energy for 24/7 supply of electricity and heat/cooling to distant locations, that have yet to be served by utility grid energy and/or telecoms, both basis for enabling all type of small-scale local business initiatives and growth.


Mini-grid renewable energy technologies represent a cost-effective, environmentally sustainable, rapidly deployable and modular tool to accelerate the pace of electrification in the emerging markets. This solution may serve farmers and people in rural areas as well as 90% of the estimated over 70 million displaced persons in refugee camps that have no or limited access to electricity (source: IRENA). Mini-grids are normally configured off-grid and operates autonomously in stand-alone mode.


Micro-grids are normally connected and have an interactive relationship to the main grid, as both then may obtain service from each other. Micro-grids may serve local communities of various sizes, even entire municipalities as islands and remote locations in mountains or deserts. As of 2018 some 2,260 microgrid networks, representing approximately 20 GW of capacity is an estimation across seven continents. Solar PV powered mini/micro-grids don’t just have the potential to bring electricity to new markets, they can also replace diesel-powered generators commonly used in unstable and poorly underserved markets.


Micro grids have proven successful in rural markets as an alternative to connecting to national grids but have also started to be used in cities to protect from power outages. Actually, a global capacity of approximately 7,500 MW from microgrids is estimated likely in the market within a 3-years’ time. Moving away from a large-scale grid models and towards decentralization and peer-to-peer power trading could help to mitigate grid failures with wide-reaching consequences, such as the recent US power-outages (refer our previous article).


Utsira, SMART ISLAND – Sustainable Energy Integration


An example of an island based smart micro-grid being designed, developed and deployed is found in the North Sea just outside the southwestern coastline of Norway and the city of Haugesund. Utsira, the smallest community of the country with a population of some 210 individuals and 6.3 km2 of land, has been served by an ageing subsea cable to the coast. It is now facing add-on loads from planned new industries like on- and off-shore aquaculture fishing farms, a modified electrified ferry and green Hydrogen production by electrolysis including H2 storage tanks and fuel cells.


As micro-grids are an alternative to costly investment in new cabling, a new Battery Energy Storage System (BESS) has been installed along with an energy management system to optimize operation of the existing 2.5 MW wind-turbines, a solar-PV park, a floating-PV plant, micro wind-power, wave-power, hydrogen power, biogas power, a 2 x 0.6 MWh battery system and continuous supply from mainland cable to grid.


The Utsira Smart Island, The Utsira “Living Lab”, is an ongoing R&D project supported by the Norwegian Research Council, a Smart Micro Grid test site for remote islands. The project will have interaction and integration with the planned establishment of a Micro Grid Test Centre under the National SIVA Catapult program, Sustainable Energy.


Local utility, public and private participants want to use the Utsira project as a testbed for smart micro-grid solutions, utilizing renewable energy resources in an optimized configuration, hence a living laboratory has been established for inventors to visit for testing of their invented smart new solutions and services. In addition, the Utsira North project, a floating wind power plant, is being projected just outside of the island, where this area and South North Sea II combined may provide the development of four 500 MW of floating wind power parks.


In addition, Vehicle to Grid (V2G) will be investigated in connection to the electrification of the ferry. Measurement equipment is being installed at the point of connection of the subsea cable, and other places in the grid to get more data for the load flow analysis. This project is closely connected with another pilot where the role of market designed flexibility in the EMS system is investigated and tested.


The island holds public charging stations for EVs, and the ferry may find loading capabilities both at Utsira harbor and at the harbor of mainland Haugesund on her journey. The public visiting the island may even base their urban in-city transportation on an electrified fleet of buses or continue on the city’s planned build of an electrified autonomous “waterbus” with 12 passenger capacity, that will serve the inner islands of the city, operated by joystick from land. True proofs of the progress for an electrified society.


Solar PV internationally


An unbelievable 1.2 billion people are still without electricity globally, of which 600 million in Sub-Saharan Africa only. Solar, an obvious available energy source to serve a majority of these people, can be easily deployed with today’s solar cell technology based on silicon in standard solar panels on grounded racks, or floating on water/sea (providing enhanced performance from cooling effect) or fixed to rooftops housing.


The Photovoltaic (PV) industry has been growing. Last year 140 GW (gigawatts) was produced from PV globally. PV is now probably the cheapest way to make a kWh of electricity, and the price level is continuing to decline. We have seen PV-systems deployed in African and Asian rural areas, as stand alone connected to unstable grid, or off-grid mini-grid hybrid solutions in conjunction with other renewables and storage capabilities. Project funding has been achieved by governmental institutions, international agencies and private investors together with local partners.


Summary


Solar is now officially the cheapest form of energy in history, having been confirmed recently by the International Energy Agency in their publication of World Energy Outlook 2020. The study concluded that solar and wind are both by far the most affordable sources, considering levelized cost of energy. Numerous solar applications are being introduced globally, in rural and urban areas, on- or off-grid, community-solar, micro-grid, Building-Integrated Photo-Voltaics (BIPS), PV on roofs, land, lakes, sea and thin-film solar covering vehicles, boats, windows and various electronic devices. Solar PV-systems are being successfully introduced as far north as Svalbard and Longyearbyen at 78 degrees north. For sustainability though, focus now needs to be put also on reuse and material recycling, as the future will be solar energy based, which some of examples in this article shows. More on solar applications, opportunities and challenges to benefit users and producers in our next article – coming up soon.



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