In an overall perspective of the world, the system demand of power it’s represented as a bell shape. During the night few power is demanded, while the day comes up, the power demand grows at the same time. Power Plants provide energy to the grid and the cost production rises with the peak demand, once more energy is required. A way to “fight” this peak demand is to analyse PV outputs, by integrating and connecting it into the power-grid, lowering the cost values. 17 PV solar systems produce most of their power during summer, less during fall and spring, very little during winter and it’s not available at night and on cloudy days, requiring power compensations purchases from the grid. As the clouds pass over fast output variations occur, which lead to challenges on the grid operators by compensate this power losses. This variability is shown in the following graphic.It’s obvious that daily PV output varies with the sun’s movement. In spite of this sunlight variation, grid-operators must address this variation by decreasing or increasing outputs from other types of energy power sources, normally fossil fuels are used to accommodate the daily variation. Incredibly, in some cases its used wind energy to compensate this variation once that wind generation is increased as solar power is decreased (naturally) during night, sunsets and sunrises. This is shown in the following graphic. 18From the graphic above, the black line represents the amount of power consumed in one full day. During the night, less energy is consumed while during the day the energy reach its maximum power. In red dots it shows the PV output, where it starts to produce energy by the sunrise, growing up along with the movement of the sun until it starts going down following the sunset. The green traces represent the wind generation output, which is indirectly proportional with the PV output. This is a positive characteristic, once it could be a viable source of energy that could address the need for compensate the low or even complete absent of PV outputs during night time. The grey area stands for the peak demand of the system demand, which is characterized by a period when the demand for electricity is in its maximum. 19 To meet this demand, utilities must engage alternative energy sources, possibly less efficient and more expensive, to keep up with energy consumption. PV output energy generated in the morning and early midday is less valuable than in the midday and afternoon, once the peak power demand and the PV’s max output are mismatch. 20 Solar energy have a tremendous contribution to accommodate the peak hours demand, which is when most of solar energy is generated and could help reduce electricity costs and reliability of the energy network.By integrating solar energy to the grid, this is called peak shaving which is the process of, during peak demand hours, reducing the amount of energy purchased from the utility company. Utility companies are the ones who “sell” energy and, like was said before, they have variable prices based on demand, and the pricing during peak demand hours is typically the highest. There is a lot of ways to peak shaving, such as reducing consumption by turning off non-essential equipment during peak hours, and most important, to install solar and battery solutions once much of the peak demand occurs during peak PV output. Although the existence on different solutions, peak shaving projects require a lot of details, coordination and planning, including engineering support, utility company participation, electrical contractors, among others. After all, peak shaving can be a great option to reduce expenses, and as utility expenses and demand rises, it will become a more common way to reduce energy expenses, leading to a lower peak demand, or a cost price reduction.The modern world we live today is completely dependent on energy, adequate energy supplies are crucial to our pattern of life. This development came with the industrial revolution, where machines start to take over the production of energy, agriculture, mechanic energy and together came new innovations and ideas to build a new and upgraded society surrounding by an “unlimited” supply of energy. This energy come from different resources, where most of them are derived from fossil fuels, such as oil, coal and gas. With the use of continued growth of energy demand came new problems and environmental issues, leading to limitations of this forms of energy resources. Fossil fuels are known as non-renewable energies which will lead to a depletion of the natural reserves of oil, gas and coal, as well as environmental threats such as global warming caused mainly by CO2 emissions in the atmosphere, earthquakes caused by subsidence of gas reserves and oil, sea level rising, among others. The energy demand by 2016 reached over 13.276,3 Mtoe, which 33% came from oil, 28% from coal, 24% from gas, 5% from nuclear energy, 7% from hydroelectricity and 5% from renewables, shown in the following graphic taken from BP Statistical Review of World Energy 2017. As we can see in the graphic 12, fossil fuels continue to be the main primary energy used, but the share of renewable energy sources within the global power generation mix has been growing relatively quickly since the end of the 2000’s. Specially thanks to strong cost reduction over recent years, developing countries, such as South Asia, Latin America and South Africa, are able to take over from most advanced countries on expanding renewable energy sources. 18 The mindset of world’s population is starting to mould around renewable energies, especially because we are starting to realize, unfortunately due to negative aspects, that we are compromising the normal functioning of the planet, creating great imbalances that can cause enormous catastrophes (climate change) and lead to the complete exhaustion of natural reserves of fossil fuels.In the graphic above, it shows a desire energy transition situation in the upcoming years. As we can see, solar energy will lead the energy market between all the renewable energy options, although all the advantages that this energy provide, exist also a lot of limitations and disadvantages that are being fight every day. 33Advantages and Limitations/Disadvantages of Solar EnergyAlong the will to make a shift towards renewable energies, solar energy is one of the most wanted and desire energy sources for the future. This affirmation is due to several positive aspects that solar power brings. First of all, solar energy is clean energy bringing various environmental benefits, such as no air emissions, no pollution while operation phase and it doesn’t waste fossil fuels. It uses an abundant source of energy, the great sun, which could be characterized as a very reliable source of energy, and it’s a source of energy based on technology instead of a fuel. 33–35Makes possible the idea of a future energy independence from big corporations and semi-monopolies once solar panels can be installed in remote locations, for example on top of home’s rooftops to small solar farms, creating micro-station options possible as well. This radically reduces the waste incurred in transporting energy from major stations, reduces the energy costs and can possible enhance the value of your own home! 33–35It’s a stable and secure source of energy. As fossil fuels increase or decrease in supply of fossil fuels, the inflation is directly proportional of make it less or more expensive. The cost of producing solar energy is directly to do with the amount of money spent on the infrastructure and not on the inflated cost of natural resource, which means that can expect much more stable prices. Also, its secure because of how widely distributed it could be and combined with microgrids (which can be disconnected from the larger electricity grid network if something happen) provide the most secure electricity, but takes a lot of rooftops solar power systems to produce the same amount of one or two large power plants. Require little maintenance once it’s up and running, has an easy installation, a simple rooftop works to make the installation and solar cells make no noise at all and there are no moving parts in solar cells which make them long lasting. 33–35It brings financial savings. Solar power was very expensive a few decades ago because it was a new technology and very few solar panels were installed and connected to the grid. Solar energy costs have reduce tremendously is the past few years, reaching below retail electricity in many places, making it competitive with the cost of retail electricity. But even in the case of solar energy being produced for sale to the utility, it benefits as well once the electricity is created at the time of the peak power demand, which makes it worth much more, as was explained in the previous topic, by lowering conventional electricity market prices, serving as a valuable price hedge by using a free, renewable fuel, avoid costs of new transmission and distribution infrastructures to manage electricity delivery from centralized power plants, reduce future costs of mitigating the environmental impacts of coal, natural gas, nuclear and other generation and it enhance tax revenues associated with local job creation, which is much higher than conventional power generation. At last but not least, clean water efficient which is a real dilemma around the world. Since coal, natural gas and nuclear power plants use tons of water and contaminate them most of the time, solar energy hardly uses any water at all. 34Besides all this advantages that solar energy brings along, there is some limitations this technology stills fight for and some of them are quite hard to avoid, including diluteness and intermittency problems. 36 Diluteness problem is that the sun doesn’t deliver concentrated energy, compared to fossil fuels, which means you need a lot of materials per unit of energy produced. These materials need to be mined, refined and/or manufactured in order to make solar panels and those industrial processes required a lot of energy and can cause pollution. The intermittency problem refers to the fact that the sun doesn’t shine all the time, because of the clouds, storms and fogs, aside the assurance that there’s no sun at night and has the same intensity all the time, as well as during winter it produces very little. The only way for solar to be truly useful and reliable is to form extremely mass-storage system batteries, which doesn’t exist nowadays and can add to the cost. The closest thing that exist is the world’s biggest lithium ion battery created by Elon Musk with 100 MW storage capacity, but is it enough for the continued growth of energy demand? Storing energy in a compact space itself takes a lot of resources, that’s why solar and wind power plant require backup energy to be a reliable energy-grid. 37, 38From other point of view, besides solar panels can integrate home’s rooftops a lot of times that’s no sufficient or even some people don’t want them on their rooftops, that’s why the installation area for a PV farm could be a real challenge to find and also will change the landscape of the future. 39 Solar parks will require a surface area roughly the size of Groningen. Entirely new landscapes need to be created, valued to people and economic feasibility. For some people this could be a hard challenge, for others this could only be a small challenge for spatial designers, which is being more and more common to integrate spatial sciences with sustainability and the view of a future energy neutral world full of renewable energy. The last aspect of this limitations is definitely the efficiency limitation. In a photovoltaic solar cell a number of fundamental losses occur. Photons with an energy h? > ?Eg generate only one electron-hole pair. The excess of energy (h? – ?Eg) is converted into heat. This mechanism causes an efficiency loss of 33%. Photons with an energy h? < ?Eg are unable to generate an electron-hole pair. This implies loss of solar energy in the part of the spectrum with h? < ?Eg . This mechanism causes an efficiency loss of 23%. Also under ideal conditions, a form of recombination takes place in every solar cell. This recombination is responsible for the fact that the open-circuit voltage will always be lower than one would expect on basis of the electrochemical potentials of the materials on both sides of the junction. –Prof.dr.ir. R.J.Ch. van Zolingen. 40Moreover, these are many additional losses caused by the device structure used and caused by the fact that the materials used aren't perfect. Incomplete absorption of photons with h? > ?Eg. In practice it appears difficult to absorb all photons with h? > ?Eg. Recombination losses or early recombination takes place. This means that minorities are being lost at defects before they are separated in space from the majorities. Recombination can occur both in the bulk and at interfaces and at the surface. The dominant recombination mechanism depends on the type of solar cell and the nature and quality of the applied materials. Because of early recombination, incomplete collection of minorities occurs resulting in a reduced current. Because of this recombination the open-circuit voltage is reduced as well. Reflection losses due to reflection at the front side of the solar cell, part of the incoming sunlight is lost. Shading losses once in practical solar cell structures, the front side of the solar cell will be shadowed to some extent by the metallization pattern used to collect the current. Series resistance losses also occur because of the finite conductivity of the materials used in the solar cell – Prof.dr.ir. R.J.Ch. van Zolingen. 40Although all these facts, the real important factor to make the transition to the desire situation continues to be the money costs. The demand and supply of energy will lead the speed of transition to a renewable energy source, that’s why if the PV share increases in the next years, the demand will increase as well, which will lead to a change of the growing costs of renewable subsidies and grid integration, modifying renewable energy policies in order to address these challenges, together with power market reform, new transmission lines and the expansion of distributed generation.