Green House Development System
Articles | |
| Design and development of a photovoltaic power system for tropical greenhouse cooling |
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A hybrid system can be generally defined as an electricity production and distribution system which consists of a combination of two or more types of electricity generating sources (example solar photovoltaic panels and wind turbine generators,). Hybrid systems usually also include an energy storage. Battery provides storage energy, which is delivered at the time the solar radiation is low, in cloudy periods or at night-time. Lead-acid batteries operation is characterized by the limited range of depth of discharge (DOD), the value currently being limited to a maximum of 80% at the best operating conditions. If this value is exceeded, the battery suffers from over-discharge, and permanent damage may result if the battery remains at this state for long. Armenta-Deu (3) concluded that the state of charge (SOC) has revealed to be an influencing parameter onto the battery voltage evaluation, especially during the charging and overcharging process. The inverter has to be capable of handling the maximum expected power AC loads (4). AC utility back-up would incorporate an automatic charger wired to the battery bank which would regulate charge when batteries are low and automatically cut off when batteries have sufficient operating power. The PV energy systems differ from conventional energy systems in that they have high initial and low operating costs, and using PV systems is very important, especially when their life cycle costs are competitive with the other types of conventional energy sources (5),(6). The photovoltaic (PV) module prices have dropped from $500/W peak in 1972 to approximately $4-$5/W peak in 1990 (7). Wagdy (8) and Haas (9) have stated that realistic economic analysis of PV systems is difficult to translate into an accurate long-term cost projection because of the number of complex factors involved. The price of PV system and its installation are important factors in the economics of PV systems. These include the prices of PV modules, storage batteries, the control unit, the inverter, installation and all other auxiliaries. This research presents a study on the installation and test of a complete photovoltaic hybrid system for cooling a tropical greenhouse. |
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