design 2 : diy technology (passive house standards) and number of people / appliances need to be examined. The target energy demand for the CTP lies between 1,200 and 1,500 kWh per household annually, which equates to 3.28 – 4.1 kWh per day. The peak demand per household will ideally remain below 1 kW of on demand energy at any given time. A minimum of six 240 Watt panels need to be installed per household, depending on how effectively households can manage their electricity demand. If purchased wholesale, prices as low as approximately $0.90 - $1.00 (or less) per Wp can be negotiated (e.g. Sharp ND-Q402CJ [240 Watt, $269 per panel). In order to maximize efficiency and production potential, developing a solar tracking system, integrated with a solar concentrator, would be highly beneficial. Even without concentration, solar tracking of the PV cells could improve output by 20% in winter, and up to 50% during summer months. Although self-installation would achieve cost-savings, the cost of various necessary construction materials and system components is likely to raise overall PV system costs by 15 - 30 % (mainly due to the anticipated cost of items such as solar inverters, wiring, and potentially sensors / microgrid controls). Based on preliminary findings, it would likely be most effective to have either one or several dispersed central inverters to manage the solar electricity conversion and distribution. This would greatly facilitate load / peak balancing, reduce individual costs by eliminating the need for each household to have an inverter, and limit the complexity of managing and servicing so many individual technology components. A more centralized infrastructure implies increased amounts of electrical wiring and transmission infrastructure Transmission Due to the relatively high expense of solar inverters and transmission control infrastructure, several central inverters dispersed throughout the community will control the distribution of electricity generated within, determining whether it will be used immediately or sold back to the grid. The AEG Protect PV offers 22 built in European country grid codes (including the Netherlands), with easy installation. The 3-phase string inverters are available at power outputs of 8, 10, 12.5 and 15 kVA. Designed with functions to stabilize the grid with power level adjustment, controlled reactive power input and fault-ride-through function. Multiple MPP trackers optimize the operating point for a 250-to-800 V connected string, while offering an average 98% efficiency. One of these inverters could service from 8 – 20 homes depending on the model. HEAT Collection One of the most essential features of the CTP system, and the “backbone” of the DIY scenario, is the solar collector and hot water circulation system. Given our ability to customize the system to our target parameters, it is sensible to integrate technological components to increase overall system effectiveness. We would combine the solar PV panel system with a solar heat collector, while adding a solar concentration component. Research indicates that there is potential for large efficiency gains through integration. Not only will the collector capture more heat through contact with the PV cells, but the panels themselves will function more efficiently due to the lower operating temperatures. Furthermore, by incorporating a concentrator that targets light onto both components, the potential value created by the solar concentration is increased, offsetting its’ construction costs over time. This could potentially justify the costs of including a solar tracking feature and to create an opportunity to design a truly integrated solar system for further applications outside of the CTP. Based on the solar radiation in the Netherlands and assuming passive house standards, a DIY solar collector with roughly 4 square meters surface area could provide up to 30% of the hot water needs for one household (roughly 4 people) during the winter, and up to 80% during the summer. When combined with a concentrator, and coupled with hot water storage / collection from the greenhouse, these values could be up to 60% in the winter, and nearly 100% in the summer. This is assuming that all of the heat is used for hot water (for showers, etc), and not conventional space heating, which is not required for passive house standards. By further expanding the system to include heat recapture from water drainage, composting, and other potential heat sources from the building, system efficiencies would be even greater. Typical costs for a self-built system range from 500 - 1500 € depending on the scope and complexity. Additional energy will come from a woody biomass gasifier for cooking and water heating and small-scale self-built wind turbines. Storage A hot water storage system can be constructed from insulated, reinforced plywood, lined with EPDM, with a recommended capacity of 300 L for a system of this size (and assuming 50L of 45 degree C water per person daily). The average water temperature in the tank is estimated to be at roughly 50 C during winter months, and up to 90 C in the summer. Another option is to interconnect several smaller heat resistant, well-insulated drums for heat storage abilities. Placing the hot water storage within attached greenhouse constructions can also improve system effectiveness. Temperature sensors on the collector and in the storage tank could provide feedback and assist in controlling heat distribution, and indicating optimal times for using hot water supply. Transmission Each building would ideally be designed with a storage room below containing the technologies and enable a central heat col Pagina 130
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