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5 solar panel performace factors

You have to think of the performance of solar panels like cars, obviously a Porsche 911 will outperform a Toyota Corolla. There are five major factors that contribute to how much electricity a solar panel will produce, understading the factors below will help you get the most performace out of your solar panels. The material of the solar cell: Solar panels are composed of different cell materials such as monocrystalline silicon, polycrystalline silicon, dye based solar cells, organic, plastic and even hybrid, which is a mix of different cell materials. Each type of solar panels have a cost and efficiency trade off based on their cell composition. Load resistance: Resistance becomes a factor with off-grid systems and grid-tie with battery backup. When you charge a battery with a solar photovoltaic panel. Connecting a solar panel to a battery causes the solar panel to operate at a higher then normal voltage which causes the solar panel to exceed the Maximum Power Point Tracking (MPPT) and decreases the power output. Most residential and commercial solar electric systems are simple grid tie so they avoid the batteries all together. Intensity of sunlight: Pretty obvious? The brighter the sun the more you will produce, quite simple. Technically as solar radiation decreases the solar panel’s current output will decrease as well, although the voltage output of the solar panel will not be affected as much by the intensity of sunlight. The temperature of the cell: The ambient temperature has a significant effect on how much electricity a solar panel will generate. During the hottest days in the summer, when the intensity of the sunlight is the brightest, common sense tells you on those days you’ll be producing the most electricity. Although that is far from true, the hotter solar cells become, the less efficient a solar panel becomes, silicon does not perform well in high heat. Heat is a electrical resistance to the flow of electrons within a solar panel. If your solar panels are mounted on top of your roof, airflow around the solar panels are very important to keep them cool. Ground mount and pole mounted arrays have less of an issue with airflow. Sanyo solar panels are unique because they have a higher temperature coefficient which enable Sanyo to outperform competing brands by 10%. Shading: Have you ever broke a one light bulb on a string of Christmas lights? Typically, when you break one light bulb, the a whole row of Christmas lights will go out. Even if one solar panel in a solar array is partially shaded the performance of the entire system will decrease significantly. It’s important when you...

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SMA Sunny Webbox – Visualize your performance

Typically once a solar power system owner installs solar panels, they get enjoyment of seeing their meter spin backwards. Although more system owners these days want more detailed output of how the solar power systems are performing. Customers who have purchased a SMA grid tie inverter have an easy option to add detailed performance monitoring through an add on device called the SMA Sunny Webbox. The Sunny Webbox can interface with up to 50 SMA grid tie inverters which connects to the internet through your router and uploads performance data to the free Sunny Portal. Historical data is also recorded on the Sunny Portal therefore installers and system owners can keep an eye on the system from anywhere in the world to make sure the solar panels are operating most efficiently. The internet is a great place to share information and critical data such as a solar power system performance should be easy to access, analyze and share to extend the experience of a solar power system after the installation is complete. The data can be access through any standard web browser, which is great because it will work on all types of operating systems. The Sunny Webbox connects to your SMA Sunny Boy through a RS485 cable and gives the solar power system owner the ability to remotely configure the...

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PVWatts makes estimating solar power easy

PVWatts is a performance calculator for grid connected solar power systems developed by NREL (National Renewable Energy Lab) to help non-solar expert conduct estimates for grid-connected solar photovoltaic systems within the USA. The calculator uses hourly Typical Meteorological Year weather data to forecast how many kilowatt hours (kWh) you will generate on a monthly or annual basis. You can enter parameters such as fixed mounted solar panels, solar panels on a tracker and even the azimuth to properly forecast different solar power system setups. Both version 1 and 2 of the calculator are provided for free on the PVWatts Website. I ran a estimate of how a 4.0 kilowatt (kW) solar power system would perform in Los Angeles using version 1 of the PVWatts calculator. Check out my assumptions and system performance: Station Identification City: Los_Angeles State: CA Latitude: 33.93° N Longitude: 118.40° W Elevation: 32 m PV System Specifications DC Rating: 4.0 kW DC to AC Derate Factor: 0.770 AC Rating: 3.1 kW Array Type: Fixed Tilt Array Tilt: 33.9° Array Azimuth: 180.0° Energy Specifications Cost of Electricity: 12.5 ¢/kWh Results Month Solar Radiation(kWh/m2/day) AC Energy(kWh) Energy Value($) 1 4.44 401 50.12 2 5.35 441 55.12 3 5.62 506 63.25 4 6.05 522 65.25 5 6.19 548 68.50 6 6.17 526 65.75 7 6.48 567 70.88 8 6.68 582 72.75 9 5.78 487 60.88 10 5.43 480 60.00 11 4.84 420 52.50 12 4.46 398 49.75 Year 5.63 5879 734.88 Whats the performance of a 4.0kW system in your neck of the woods? go ahead feel free to post and discuss your results...

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Touch-screen device for tracking solar panel and home energy usage

Open Energy a company I wrote about recently, that manufactured solar roofing tiles has also announced they are working on a device that helps solar power system owners visualize their home energy usage and solar panel production. The device has a wireless Internet gateway that can show solar power production along side electricity usage. The device can also pull in gas and water usage data that can help home owners make educated decisions on the fly about their resource consumption. Open Energy’s monitoring device will be out on the market next year and will cost between $1,100 to $1,400 USD which includes other monitoring services along with the hardware. More companies are developing ways for consumers to track energy production from solar panels and compare it to a home’s energy usage. Monitoring software and devices are becoming more of a standard when purchasing a solar power system. Traditionally consumers have to rely on reading the LCD screen on an inverter to figure out the production for that day. But a device or web software the analysis of the home energy usage and solar panel production can be analyzed in greater detail. Customers want to know in real time what the system is doing, we are very used to information on demand, these devices, software and hardware help solar electric system owners really understand how their system is...

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SolarMagic – Get more out of your solar panels

Earlier this week, we talked about how shading can be a big issue for solar panels. Even your neighbor’s trees can cause shading issues that can significantly reduce the performance of your system. SolarMagic a product being developed by National Semiconductor adds onto existing solar panels to increase the efficiency up to 50% in real world environments which face shading and dirt and other issues. Solar Panels are typically wired in a string fashion, what does that mean? Well remember those pesky Christmas lights? When one of your bulbs went out the whole string of lights would also go out, this is similar to how solar panels work, If even a little part of the system gets shaded, well the whole solar panel system becomes less efficient. One of these SolarMagic Units sits behind every solar panel, literally working its magic to keep each solar panel in order to maximize the energy harvest in shady or dirty conditions which would typically have a negative effect on the system. According to SolarMagic’s Website: “National’s SolarMagic technology uses our expertise in power conversion and advanced algorithms to get the most energy possible out of each panel in a solar array. Today’s systems are limited by the weakest link, and one or two compromised panels can take down the entire string or array. This is somewhat similar to a section of Christmas lights that go out when one light fails. However, with SolarMagic technology, if one panel in a solar installation is shaded, dirty, or otherwise compromised, that panel is allowed to produce what little energy it can while the other panels continue to operate at their full potential.” According to the company the SolarMagic unit measures 10 x 12 cm and is currently being field tested and is already proving that the technology works in real world conditions. Field tests show a 45% increase in solar pv panel efficency! The product will be on the market next year! We’re looking forward to getting our hands one a couple of these puppies to see how they...

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