1. Red Rocks Community College ENY 130 Grid-Tied PV Fall 2009 Module 2

2. Grid-Tied Applications: Anything that utilizes electricity Flexible design works for both residential and commercial applications

3. Advantages of Grid-Tied Improved Economics: No need for a large system to cover all needs. No need for the cost of battery back up High start-up loads can be provided by the grid PV power always offsets grid power and reduced electrical bills Net metering Design Flexibility Most any size system can be connected to the grid Though must be able to support the grid voltage Cannot exceed 600 volts Increased reliability Two independent power systems-redundancy Can offset electrical needs during potential brown out

4. Disadvantages of Grid-Tied When utility power goes down, so does the power from the inverter to the building. You must have a separate system beyond the grid-tied portion of your system for the PV to provide power while the grid is down.

5. Grid-Tied Components Source: Powered naturally

6. Watt vs. Watt Hour This is often a confusing concept A PV system is sized by “Watts” The PV power produced is the watts multiplied by the duration of production. A 4kW (kilowatt = 1000 watts) PV system producing for 6 hours produces 24000 watts, or 24 kWh (kilowatt hours)

7. Which produces more work? Two guys working hard…. Or 1 PV module laying in the Sun ?

8. Energy Comparisons Average home consumes 22 kWh/day(8000kWh/yr) 1 person generates 75w/hr (x 8hrs=.6 kWh/day) 1 ton coal = 2460 kWh (costs $300) 32,800 labor hrs (value@$20/hr = $656,000) 1 Barrel of oil = 1700 kWh (costs $100) 22,600 labor hours (value@$20/hr=$450,000) 1 Solar Module = 1.2 kWh/day(40yrs is 14,500 kWh) (Value @ $20/hr = $300,000) 16 Labor hours 1 solar module laying in the sun produces as much energy as 2 people working

9. AC / DC Alternating Current -where the direction of current flow reverses at frequent intervals. This is the current provided by utilities Direct Current -where electrical current flows in one direction. Typical of batteries and PV cells.

10. Alternating Current wave

11. Direct Current…wave

12. Electrical Circuits Electrical Circuit is the continuous path of electron flow from a voltage source. Open Circuit- when there is no completed path for current. Switched off or wires disconnected Closed Circuit- when path is completed and current flows. Switched on.

13. Series and Parallel Circuits

14. Series Wiring….. Which one? …… The voltage is added while the amperage stays the same

15. Parallel Wiring…..which ones? ….. The amperage is added while the voltage stays the same

16. Series and Parallel wiring of Modules

17. Series and Parallel Exercises in Book End of 2