Sunny Boy 3800U, 3.8kW Grid Tie Inverter

     SMA's new 3800 watt inverter processes solar energy at an unparalleled 95.6% efficiency and is the first of a new generation of inverters by SMA to be released in America. These new inverters incorporate a cast aluminum housing used to separate the control and power electronics. This new chassis design is incredibly rugged, lightweight and weatherproof. The power electronics compartment integrates SMA's new OptiCool TM airflow technology where cool air is drawn in through the bottom of the enclosure by convection, drawn around the power electronics where the air absorbs heat and is the released through a side vent. When required, this process is assisted by a temperature controlled fan. The built in meter displays system status as well as the solar energy being produced by the power plant and other key information on the LCD screen. Several meter and software options are available from your SMA supplier.

Use the SMA America String Sizing Utility program to determine the size and configuration of your system. (Please read the disclaimer before using the sizing tool, and do not hesitate to contact the knowledgeable staff at The Alternative Energy Store with any questions you may have!)

Sunny Boy 3800U Technical Data

STC

STC (Standard Test Conditions) is the test condition used to give PV panels their power ratings. When determining the STC rating, the PV panel is hand selected (usually the best cells in the lot), flashed with a controlled light source at 1000 W/m2, with the cell and air temperature at 25°C (68°F) and 0 m/s wind speed.

Basically, when the PV panel is flashed with the light source the power output is measured. So, a panel which has a rating of 165W on the rating label (typically shown as Maximum Power and represented as Pmax), will produce 165W of DC power when subjected to the STC test conditions. These conditions are, in fact, far from real-world.

PTC

PTC (PVUSA Test Conditions) are defined as 40°C (104°F) temperature, 1000 W/m2 solar irradiance, and 1 m/s wind speed. This test was developed in an attempt to simulate what happens in a real-world outdoor installation. Usually, the PTC rating for a PV panel is between 70% and 85% of the STC rating. The reason that the PV panels produce less power under these conditions has to do with the material properties of the panels themselves. Most PV panels become less efficient as their temperature increases, and so they produce less power to the inverter. This property is roughly linear in the temperature range under which PV panels are usually exposed. Each manufacturer assigns a value to this characteristic, and it is usually expressed as a percentage change of the total power per °C.

For example, if a panel has a temperature coefficient of power that is -0.50%/°C, the panel produces 0.5% less power for every 1°C increase in temperature. As you will notice, the difference between the STC temperature and the PTC temperature is 20°C. This equates to a 10% performance difference between the two conditions due to ambient temperature alone. The PTC rating (which is closer to most real-world conditions), will produce 10% less power than the power shown on the rating label of the PV panel.

Any material that is exposed to sunlight will heat up as it absorbs the infrared radiation that the Sun produces. Dark colored surfaces tend to become warmer than light colored surfaces. PV panel are typically fairly dark colored, and tend to warm significantly due to the Sun's insolation. A PV panel mounted in direct sun with no wind blowing can be as hot as 70°C or 80°C.

If we perform our calculations again, with the panel at 70°C, we arrive at a power output of 124W per panel, or 75% of the STC rating. This number must be multiplied by inverter efficiency to arrive at inverter output power.

Cautions

Because of danger to life and property that improper installation of these systems can cause, you must have your system and its components selected, designed and installed by an appropriately certified electrician. Please note, having the system installed without a licensed electrician will also void the warranty.

The California Energy Commission's Emerging Renewables Buy-Down Program offers cash rebates on eligible renewable energy electric-generating systems. You can get a rebate of up to $3,000 per kilowatt, or 50 percent off your system purchase price (whichever is less), making it more affordable to generate your own electricity using renewable energy. All types of electricity customers are eligible: residential, commercial, agricultural and industrial. Program participants can buy their electricity from any electric service provider, but their proposed site for the renewable energy system must be within the electric utility service area of: Pacific Gas and Electric, San Diego Gas & Electric, Southern California Edison, or Bear Valley Electric Company. The participant must also remain connected to the utility grid. For more information on the California Emerging Renewables Buy-Down Program, check the CEC's web site at http://www.energy.ca.gov/greengrid/index.html, or call toll free at (800) 555-7794 (in California) or (916) 654-4058 (outside California).

California isn't the only state to provide incentives for people to purchase grid intertie systems or renewable energy systems period. To see a complete list of all the incentives that each state provides see the University of North Carolina's website: http://www-solar.mck.ncsu.edu/dsire.htm . Don't forget to bookmark this page so you can come back to see this kit.