SOLutions in Solar Electricity

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 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. 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 ship to freight truck delivery locations in the continental U.S. Freight charges are always going up so we recommend that Alaskans and Hawaiians buy from local suppliers. 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. We can process orders and ship equipment in 1 or 2 business days. Delivery is typically within 2 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 only 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?
Use a combination of these 3 methods to determine how much PV to buy.

One Determine your kWh electric consumption. Then match PV production to your electric consumption. For example, you consume 600 kilowatt-hours per month (kWh/month) and want to produce 100% of your electricity with a PV system with no battery backup. 600 kWh/month x 12 months equals 7,200 kWh/year or approximately 20 kWh/day. Most of the U.S. has 3.5 to 5 Sun Hours of solar input. This means that a 1 kilowatt AC PV system in a 4.5 Sun Hour region will produce 4.5 kilowatt-hours per day. 20 kWh/day divided by 4.5 sun hours equals 4.4 kW AC. Go to PVWATTS at http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/ and enter your location, 4.4 kW, your roof tilt and orientation. See your monthly and annual estimated PV production for a 4.4 kW system or any other size system. To determine the number of solar modules you require, take your PV system kW AC x 70% to 80% to factor in DC-to-AC conversion (65% for battery systems). We consume approximately 6,000 kWh/year and our PV system supplies over 75% of our energy.

Two Match your PV array size to your roof space. You need full sun on your solar array all day (from at least 9am to 4pm). Trees, chimneys, vents and other buildings can block the sun or make array installation difficult. Our office and south-facing garage roofs had enough space for our 225 sq. ft. array (32 70-watt modules). Our home south-facing roof had more than enough space for the 140 sq. ft. array (20 75-watt modules).

Three Match your PV system cost to your budget. PV modules are about half of the total system cost. Our 1998 system costs $20k. Our 2,240 watt array costs $11k. The other equipment you may need depending on your system configuration are mounting hardware, combiner boxes, disconnect switches, power center, charge controller, inverter, battery bank and wiring. Our 2007 batteryless PV system addition cost $14.3k. Both systems were eligible for state solar incentives and federal tax credits.

In summary, use your electric consumption, the available array space and your budget to plan your PV system. Start with a system that fits your budget and plan your wiring for later expansion.

Example: You consume 20 kWh/day and live in an area that gets 5 sun hours and you want to produce half of your energy with the sun. 20 kWh/day divided by 2 equals 10 kWh/day divided by 5 sun hours equals 2,000 watts AC. Crystalline solar modules produce approximately 9 watts AC per square foot. 2,000 watts divided by 9 W/sq. ft. equals approximately 225 square feet solar array. 2,000 watts AC times 1.3 for batteryless PV (70% DC-to-AC conversion) equals 2,600 watts DC. 2,600 watts divided by 150-watt solar module equals 17.3. So you need approximately 18 solar modules. Other factors like inverter voltage have to be considered. Email us and we will design your system for you.
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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 solar array temperature loss (5% to 12%), dust and dirt (2% to 4%), module mismatch (2%), DC and AC wire losses (2%), real inverter loss (5% to 15%) and electric storage loss (1)%) 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.

We take these and other design parameters into consideration when we design your PV system.
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