Question

3. Analyze this PV/battery system (ignore battery discharge rate and temperature constraints): 1. PV Module characteristics: PR-100W, VR-20V, Voc 22V, IR-5A, Isc 6A 2. Battery characteristics: 6V, 100Ah (each) 3. Coulomb efficiency 90%; Maximum discharge 80% 4. Insolation: 6 kWh/m'day 5. Inverter efficiency: 80%; 6, Dirt, etc, efficiency: 90% (10% loss) 6 kW/m2-day 80% efficient AC 6V 100 Ah a. Find the watt-hours/day that would reach the loads (assume all PV current passes through the batteries): b.If the load requires 600Wh/day, for how many cloudy days in a row can fully- charged batteries supply the load? Consider the design of a small PV-powered light-emitting-diode (LED) light. The PV array consists of 8 series cells, each with rated current 0.3A@ 0.6V. Storage is provided by three series AA batteries that each store 2Ah at 1.2V when fully charged. The LED provides full brightness when it draws 0.4A @ 3.6V 4. On/Otf 3.6V 0.4A Of 3 AA LED ight The batteries have a coulomb efficiency of 90% and for maximum cycle life can be discharged by up to 80%. Ignore any complications associated with temperature, dirt, discharge rate, etc. a. How many hours of light could this design provide each evening if the batteries are fully charged during the day? How many kWh/m2 -day of insolation would be needed to provide the amount of light found in (a)? with 12%-efficiency cells, what PV area would be required? b. c.

Answer 1

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