| SOLutions in Solar Electricity |
How
do I place my equipment order?
After we have reviewed
your power requirements and designed your PV system, you simply place your
order. You can pay by personal check, bank check or bank transfer to SOLutions
in Solar Electricity. References available upon request. Our mailing
address is: SOLutions in Solar Electricity, P. O. Box 5089,
Culver City, CA 90231
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Do
you take credit card orders?
Yes, but we are
very cautious because there is a lot of credit card fraud. You can use
Mastercard or Visa if you want to pay the additional 3% that the credit
card processing company charges. We encourage you to save your money and
instead pay by check or bank transfer.
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Can
you order on-line?
No. You can order THE NEW SOLAR ELECTRIC
HOME book on-line, but we are not an on-line store. We give you expert
advice and custom PV system design.
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Do
you ship to Alaska, Hawaii and take international orders?
We do not ship to
Alaska or Hawaii. Freight charges are always going up so we recommend that
you buy from local suppliers. We do ship by UPS and freight truck to locations
in the continental U.S. We only accept international orders that are paid
by bank transfer.
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How
long does it take to get my equipment?
Orders are promptly
shipped directly to you from the equipment manufacturer or from distribution
warehouses. We drop-ship direct to you to eliminate extra handling costs
and shipping fuel consumption and pollution. Delivery is typically within
3 weeks.
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How
do I check the status of my order?
Please Email
us or call 310-202-7882.
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What
about sales tax?
We charge California
sales tax to deliveries in California only.
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What
are the product warranties?
We sell new, first
quality equipment that carries the manufacturer's warranty. Module warranties
are 20 to 25 years on power output. A 30 year design life for PV systems
is realistic, but solar modules should last even longer. The best way to
determine a module's potential life is by how long the manufacturer has
produced that specific cell technology and by that model's measured field
performance. Inverters have 5 or 10 year warranties.
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How much PV do
I need?
Read THE NEW
SOLAR ELECTRIC HOME book to determine how much PV to buy. Then
Email us to finalize your
design and order your equipment.
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What's
the difference between STC and PTC and real-world AC?
STC stands
for Standard Test Conditions which are 1,000 watts per square meter solar
irradiance, 1.5 Air Mass and 25 degrees C. cell temperature. STC
are indoor factory test conditions. PTC stands for PV USA Test Conditions
which were developed at the PV USA test site at Davis, California. PTC
are 1,000 watts per square meter solar irradiance, 1.5 Air Mass, and 20
degrees C. ambient temperature at 10 meters above ground level and
wind speed of 1 meter per second. PTC is more like "real-world" conditions
but does not factor in dust and dirt, module mismatch, DC and AC wire losses,
actual inverter efficiency, and electric storage efficiency if you have
batteries.
The higher the cell temperature which is perfectly normal in the real world results in the lower power. Silicon crystal cells average about 30 degrees C. above ambient temperature in the real world and cell voltage drops as temperature increases (amps change very little). Volts times amps equal watts which is power. Thus, a module's power output in the real world is lower than its power when measured in the factory where cell temperature is controlled to 77 degree F. (25 C). A rough rule of thumb is deduct 10% from STC for single crystal PV, 12% for polycrystalline PV and 5% for amorphous silicon PV. For example, a 150-watt polycrystalline solar module in bright sun may only put out 132 watts DC and 120 watts AC.
Real-world AC factors
in solar array temperature loss (5% to 12%), dust and dirt (2% to 4%),
module mismatch (2%), DC and AC wire losses (2% to 3%), real inverter loss
(5% to 15%) and electric storage loss if you have batteries (15%). Well
designed batteryless PV systems usually have a DC STC-to-real-AC conversion
efficiency of 75% to 80%. Well designed battery PV systems usually have
a DC STC-to-real-AC conversion efficiency of 65%. For more information
read THE NEW SOLAR
ELECTRIC HOME book.
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