Large-scale energy storage solutions also serve for other applications in the power grid which makes them considerable options for solar power plant developers. This proposal also increases self-consumption which reduces energy demands. Promoting distributed small-scale energy storage devices in households and commercial buildings to reduce the amount of excess solar energy during midday. The South Australian government also came out with another solution. To solve this problem, the excess solar power generation needs to be shifted to be consumed at night, and the only way to do that is by storing it in a large-scale energy storage facility. In other words, ISOs need to curtail excess solar energy during midday which means that large-scale PV energy is being wasted. If the excess solar energy generated during the midday is not curtailed by grid operators, then the duck curve problem appears in the scenario. The Need for Energy StorageĬountries with a high PV penetration in the power grid such as Australia are already facing these problems. Moreover, if these power plants are off-line reserves and need to be rapidly turned on to supply incoming energy demands, then the cost to run the power plant increases radically, representing a non-optimise and deeply contaminating solution. This creates a problem in which other energy sources need to rapidly ramp up power production to follow the demand curve which is generally met by thermal or nuclear sources. Moreover, solar energy generation ends during late afternoon hours, precisely when demand tends to increase in the power grid. Midday demand reduces drastically while early morning demand values do not. The integration of this generation pattern in the power grid, changes the demand curve, following a duck shape graph as it can be seen belowĮnergy Demand Curve of California Power Grid with Increased Solar Power Generation. Solar generation follows a Gaussian shape curve that has its peak value at midday and that rapidly starts early in morning hours while finishing rapidly in later-afternoon hours. When a large section of the power grid depends on a variable source of energy, large uncertainties in generation availability appear in the scenario, making it harder for grid operators to keep stability values in the power grid. Controllability of these renewable energy power plants is lower as energy production depends on environmental factors (available solar radiation) which cannot be accurately predicted.ĭue to this variability and due to government policies that establish a preference for renewable energy sources over carbon-based power plants, every MWh generated from large scale PV plants needs to be injected into the grid. Solar power plants are inherently more unstable and uncertain than traditional thermal generation plants. Grid operators establish spinning reserves and off-line generators to act quickly to balance the power grid among other mechanisms. This mathematical forecast is later used by grid operators to estimate the power generation plants that need to be connected to supply these energy demands. This can be done by forecasting energy demands based on historical records of variations according to seasons and daily changes. ISOs need to accurately predict energy demands with weekly, daily and even 15 minute time frames. Every second, the power grid must be balanced between demand, generation, and energy losses to avoid stability issues and control voltage in busbars across the grid. The power grid is controlled by government or private organisms called ISOs which establish the power flows across the transmission lines according to energy demands and energy generation. However, as solar PV plants spread across the power grids, new challenges arise for Independent System Operators (ISOs) who balance the electricity flows.
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Moreover, according to the latest Lazard´s report, the levelised cost of energy of utility-scale PV plants is as low as $40/MWh, lower than coal ($60/MWh), nuclear ($112/MWh) or gas peaking ($152/MWh).ĭue to these technical, economic and environmental reasons, project developers consider solar power as a valuable resource that can be offered to serve commercial or utility-scale power projects by using simulation software like PVsyst, SAM, or PVcase, to show the energy results and economics of these projects. Technical experience in the design of solar projects encourages developers to carry on utility-scale projects under solar power while at the same time the reduced carbon footprint of these power plants makes them more attractive for governmental organisations With over 400GW in capacity installed worldwide according to the Global Renewable Energy Status Report 2018, the deployment of solar power plants seems unstoppable. The development and advantages of solar energy are indisputable.