Alternate Systems
Using the developed West Whins PyLESA model, the performance of future system alterations can be simulated and analysed based on findings within literature. The purpose for doing this is to make recommendations for the future generation of smart grid systems, such as the proposed development of North Whins apartments.
Electrical Storage
The West Whins system currently only has a storage tank for hot water and no electrical storage. (Flett, et al., 2020) (Bremdal, et al., 2018). A 13.5kWh Tesla power wall is introduced to our west whins model to reduce the overall imports. This has a round trip efficiency of 90% as specified on the manufacturer datasheet. (Tesla, 2018) The Tesla power wall is chosen as it is already being utilised for other Findhorn homes. (Easter, 2020)
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Figure 1: Total electricity demand for West Whins over a one-week period with electrical storage installed
Figure 1 shows the electrical demand of West Whins being met by various sources, including renewable energy supply, imports and electrical storage using the fixed order controller in PyLESA. By introducing electrical storage to the West Whins model, the demand met by imports can be reduced when there is no renewable energy supply available. By running this simulation over the course of a year it is found that this reduces the imports by 14%. However, exports decrease by 22%, due to the charging of the electrical storage. This shows less overall efficiency due to losses from charging/discharging, however this also shows more local use of the available renewable energy supply and improved economic performance.
PV Panels
Twelve LG2901C PV panels are introduced to the West Whins model to increase the overall renewable energy supply. Under nominal operating cell temperatures, these are advertised to give a maximum power output of 213W. (LG, 2013)
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Figure 2: Total renewable energy generation for West Whins over a one-week period with PV panels installed
Upon introducing twelve PV panels to the West Whins model, the renewable energy generation increases by 4.3% over the course of the year. Figure 2 shows the effect on the total renewable energy generation by increasing the supply periodically. As seen on the 55th hour PV generation may coincide with wind generation which ultimately leads to exports. These PV panels reduce imports by 5% and increase exports by 5% over the whole year as more on-site energy is produced.
Overall Results
Finally, both the Tesla power wall and the twelve LG PV panels are introduced to the model together. Electrical storage can utilise the excess renewable energy supply for when there is a lack of wind or PV generation.
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Figure 3: Grid interactions for West Whins over a one-week period with both electrical storage and PV panels installed
Figure 3 shows the grid interactions over a one-week period upon implementing both PV and electrical storage to the West Whins model. During this period, five days pass before any imports from the grid are necessary. This is because renewable energy supply is in excess, indicated by the high exports. By implementing both technologies together in the West Whins model, it is found that imports decrease by 19% and exports decrease by 18% over the course of the year.
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Table 1: Annual grid interaction and cashflow simulation results for all six West Whins flats
Table 1 displays the total imports and exports from each configuration over the whole year, as well as the annual cost of electricity for the individual West Whins flats. By implementing any of these technologies, it is found that the residents can save between £149 and £63 per year on the economy 7 tariff, depending on their configuration. This shows an improved economic performance regardless of whether exports go up or down due to imports being reduced more in each case. Downloads to each of these simulation input files can be acquired here.