Self-Test Questions
Solar Power Questions and Answers
Basic Concepts
1. What is the difference between a kiloWatt and a kiloWatt-hour? (Section: Solar Energy Concepts)
kW: kilowatt, a measure of instantaneous power output (like speed, km/h) kWh: kilowatt-hour, a measure of total energy consumption or production over time (like distance (km)
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2. Does a grid-connect solar power system provide power during a blackout? Why or why not? (Section: Systems)
No, it shuts down in order to protect workers that may be fixing the electrical lines in the area.
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3. What components does a standard grid-connect solar power system consist of? (Section: System Components)
Panels, inverter, roof mounting, circuit breakers, meter, and the wire that connects them
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4. What are three common types of PV panel? (Section: Panels)
Amorphous, monocrystalline, polycrystalline
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5. Are inverters silent? (Section: Inverters)
No, they make a small amount of noise, conceptually similar to a refrigerator
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6. Do PV panels and inverters perform better when hot or cold (Section: Panels, Inverters)
When cold. Keep the inverter out of direct sun, and try to ventilate the panels for maximum performance.
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7. When is over-sizing the inverter a sensible thing to do? (Section: Inverters)
Whenever the customer has the likely intention of increasing their system size at a later date, and has adequate roofspace for future expansion.
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8. Is roof reinforcement required for PV systems (Section: Roof Mounting)
Almost never but consult your building engineer if in question.
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9. What are the two types of metering and feed-in tariffs? Which type does NSW have? QLD? (Section: Meter)
Net and gross metering; net and gross feed-in tariffs. NSW = gross; QLD = net.
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10. Under what circumstances are Solar Credits more advantageous than the rebate? (Section: Upfront Government Support)
For businesses and households with joint income over $100,000
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11. How can residents of states with a net feed-in tariff increase the revenue from their solar power system? (Section: Feed-in Tariffs)
By increasing the size of the system, and by shifting deferrable load to night time operation. For example doing your clothes washing, ironing, vacuuming etc. outside of peak sun light hours.
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Advanced Concepts
1. Why is a Maximum Power Point Tracker needed? (Section: Panel Characteristics) Because the power output of the panels vary with sunlight intensity and temperature, the resistance of the load must be adjusted to maximise the power output.
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2. What de-rating factors should be taken into account in a performance estimate (Section: Performance Calculations)
Tolerance of Panel Manufacturing process (ie. Is the panel positive/negative tolerance or positive tolerance like Hyundai Solar panels), Inverter efficiency, panel mismatch, voltage drop across connectors and blocking diodes, dc wiring, ac wiring, soiling, system availability, shading, age
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3. How does shading vary with panel configuration (Section: Effect of Shade)
Multi-string configurations are more shade tolerant than single string configurations. Shading along the panel length is less critical than shading across the panel width. Generally speaking it is advised to not install where shading is an issue.
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4. What is a rule of thumb for the minimum set-back between rows of elevated panels? What factors affect the minimum set-back distance? (Section: Minimum Set-back)
Between rows of 30° inclined north-facing panels, rows should be spaced by 2.25x the panel length. The orientation, inclination, row length, and the string configuration affect the minimum set-back
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5. What makes larger systems better long term propositions? (Section: General)
Greater amount of gross profit, greater environmental benefit, more efficient inverters, larger insulation against electricity price rises, economies of scale during installation and when replacing inverter.
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6. On what date does the solar multiplier reduce to 4x? (Section: Rebates and REC Market)
1st July 2011
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8. What is the feed-in tariff cap on system size in your state? Is a site with 125 MWh eligible to receive the feed-in tariff in your state? (Section: Advanced Feed-in Tariff Concepts)
Answers vary by state.
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9. What shortcomings does the financial concept of payback have? (Section: Financial Concepts)
Electricity price rises can shorten true payback, but panel degradation or failure can delay payback. Profits are reaped only after the system has paid for itself. ROI is based on a ‘point in time’ and does not take into account increasing electricity prices, inverter failure.
