11. Terminology
An equinox is when the plane of the
Earth's equator passes the centre of the Sun
• 20 March and 22 September
A solstice is when the Sun reaches its highest or lowest
excursion relative to the equator
• 21 June and 21 December
12. Terminology
The solar azimuth angle is the compass direction of the sun
The solar elevation defines how high the sun is.
15. Solar Thermal
Solar Water Heating (SWH) or Solar Hot Water (SHW)
• Close Coupled
• Pump Circulated
• Direct (Open Loop)
• Indirect (Closed Loop)
16. Solar Hot Water
In a "close-coupled" system the storage tank is horizontally
mounted immediately above the solar collectors on the
roof. No pumping is required as the hot water naturally
rises into the tank through thermosiphon flow.
In a "pump-circulated" system the storage tank is ground-
or floor-mounted and is below the level of the collectors;
a circulating pump moves water or heat transfer fluid
between the tank and the collectors.
18. Solar Hot Water
• Direct or open loop systems circulate potable water through
the collectors. They are relatively cheap but can have the
following drawbacks:
• They offer little or no overheat protection unless they have a heat
export pump.
• They offer little or no freeze protection, unless the collectors are
freeze-tolerant.
• Collectors accumulate scale in hard water areas, unless an ion-
exchange softener is used.
19. Solar Hot Water
Direct systems
(A) Passive system with tank above collector.
(B) Active system with pump and controller driven by a photovoltaic
panel
20. Solar Hot Water
• Indirect or closed loop systems use a heat exchanger that
separates the potable water from the fluid, known as the
"heat-transfer fluid" (HTF), that circulates through the
collector.
• water and an antifreeze/water mix.
• After being heated in the panels, the HTF travels to the heat
exchanger, where its heat is transferred to the potable
water.
21. Solar Hot Water
• Indirect active systems
• (C) Indirect system with
heat exchanger in tank
• (D) Drainback system
with reservoir.
• In these schematics the
controller and pump are
driven by electricity
24. Solar Energy
“Pho-to-vol-ta-ics” – “PV”
“photo” = light
“voltaic” = produces voltage
• Photovoltaic (PV) systems convert light
directly into electricity (using semi-conductor
technology)
27. Net Metering
• Net metering is an electricity policy for consumers in
which owners receive credit for at least a portion of
the electricity they generate.
The utility grid is a two-way street
If usage is low during the day, electricity is “sent back”.
At night, when the solar system is not producing, the
credit from the daytime is used
30. Solar Power Plants in CA
• Solar Energy Generating Systems (SEGS)
• Largest solar thermal in the world
• Barstow, CA
• 1984 – present
• 354 MW power
31. Solar Power Plants in CA
• Nellis Solar Power Plant
• Nellis Air Force Base
• 2007 – present
• 14 MW power
32. Solar Power Plants in CA
• Ivanpah Solar Power Facility
• 40 miles southwest of Las Vegas
• 392 MW power
• World’s largest solar farm
33. Solar Power Plants in CA
• Ivanpah Solar Power Facility
• Environmental Controversy
• Tortoise Habitat
• Migratory Bird Death
• Water Use
• Fire
