Do you know the benefits of Photovoltaics to save our planet?
PV systems produce no atmospheric emissions or greenhouse gases. Compared to fossil-generated electricity, each kilowatt of PV electricity annually offsets up to:
16 kilograms of nitrogen oxides
9 kilograms of sulfur oxides
2,300 kilograms of carbon dioxide (CO2)
If the industry grows by the 25% per year as predicted (see U.S. PV Industry Roadmap (PDF 674 KB) Download Adobe Reader). PV in the United States will offset 10 million metric tons of CO2 per year by 2027 — equivalent to the annual increase emitted by U.S. fossil fuel electricity generation. This means that the emission rate will become negative thereafter as the PV contribution grows!
The placement of PV-Solar Panels is for most people a substantial investment. And naturally we want to maximize the returns on that investment. We therefore want to achieve a maximum output.
The Power Optimization Technology in the Photovoltaics Technology is a specialized area to study the conversion of DC to DC power in order to harvest more power from the PV module. At the same time, the natural losses of energy during the energy conversion processes in the PV system can also be reduced using the basic logics of electricity in order to harvest more power.
http://en.wikipedia.org/wiki/Power_optimizer
As you know that the crystalline module market had already begun tilting in favor of buyers.
As customer selectivity increased, product reliability- both actual and perceived, based on company reputation-quickly emerged as an essential divider between desired modules and shunned brands. Quality and durability are very important, because ultimately, customers are interested in how much energy the solar system is going to produce over a long period of time. The dependability of the modules has now become a central element of the company's brand-differentiation strategy in the competitive crystalline module sector. The module manufacturers like to sell their modules by showing even the tiny incremental gains in the module efficiency in this competitive market. So the product advancements will take the form of steady quality improvement and greater durability.
As per Enviroharvest and Ramen, these following natural losses your PV system using power optimizing solutions.
Energy loss within the Solar Module
Spectrum: Differing semiconductor materials or combinations are suited to specific spectral ranges because of this a portion of the radiant energy cannot be used because the photons have insufficient energy to activate electrons across band gap (charge carriers).
Heat: An amount of surplus photon energy is transformed into heat rather than into electrical energy. Heat adversely affects solar cell performance.
Optical: Losses resulting from shadowing of the cell surface through contact with the glass surface or reflection of incoming rays on the cell surface. Even 10 percent shading on a panel can lead to a 50 percent reduction in the amount of energy harvested. If even one full cell in series string is shaded, it will likely cause the module to reduce its power level to ½ of its full available value. If a row of cells at the he bottom of a module is fully shaded the power output may drop to zero. Soiling can reduce output 5-20%. Mismatch between panesl can reduce output by 15%. Due to the semi-conductive nature of silicon cells, small amounts of shade (fist sized) can completely disable the output of a module or even a string of modules (non-producing cells become non-conductive). PV systems with any shade will have production loss. Shade is quantified in terms of percent solar access. Shade measuring tools such as the Solar Pathfinder or Solmetric SunEye can be used to provide both monthly and annual solar access measurements.
Resistance: losses through electrical resistance in the semiconductor and the connecting cable.
Downstream Energy Loss
Resistance: Electricity traveling through wires encounters resistance. The lower the voltage and higher amperage and the longer the longer distance electricity runs the higher the electrical loss.
Conversion: The array cannot be directly to the battery but usually we want an intermediary so to regulate battery charging. Battery charging electronics are ~70 to 90% efficient.
Battery: Power is lost in putting the electricity into and extracting it out of the battery. This is ~75% to 80% efficient.
Overlooking the loss due to wiring and electrical connections: the end-to-end efficiency of the system is therefore approximately 7% to 8% . Centralized optimization reduces overall performance to the weakest panel.
Assessed with prudence, these variables can provide a pretty accurate look at the future electricity output (in kWh) of a given system. While a lot of factors are beyond our control, some simple rules can result in a gain of 10 – 20% on your Solar production. Remember, conversion of energy will always result in a loss. The efficiency rate of the panels is already at the low side of the scale.
The most important degradation process is relative to PV panels: account 1% per year (loss of efficiency). In 20 years (guaranteed lifespan) the efficiency will be 20% lower. The cause is a loss of properties in materials (glass transmitivity, PV cells efficiency). Inverter can also reduce its performance in the time.
At low voltages during the shadow conditions of the cells in the PV modules, the amperage within your system is high. A lot of electrons want to travel through the wires that connect your panel to the inverter. Just like a highway, a lot of traffic needs more lanes to keep cars moving smoothly. Under dimensioned wiring means resistance and that equals loss. Since heat is not what we are after we have to decrease the resistance of our wiring by slightly over dimensioning them. Changing wiring further increased output with 5%.
By changing the design of system that gained about 15%.
The Power loss in your wiring is easily calculated with this equation:
power loss % = (1.7 x current x length of wire)/(voltage x wire area)
Temperature and Solar Arrays – Increase in Temperature means Decrease in Efficiency
The moment the sun starts to shine on your Photovoltaic panels their temperature will rise. As we all know that the multicrystalline solar panels work with an efficiency rate of about 15 – 18%. That is the amount of incoming solar energy which is actually converted into electricity. The rest of the incoming energy is converted into heat.
Good ventilation means better performance = higher output = more money is in your pocket.
Depending on latitude there is an optimal angle, which is close to latitude value. You should choose your angle depending on what you need to optimize : winter production, summer production or yearly production. The software provides the production on monthly basis for the various angles you try, then you decide which angle maximizes your function.
Positioning of your PV panels – Rule of thumb is South on a 30 degree angle.
As a rule of thumb we have our panels face southwards in a 30 degree angle to the horizon. This is the practical solution to the fact that the position of the Sun changes during the day, the season and the latitude we live on.
Beyond these above changes you do in your solar project design, the new power optimization technologies that work with the solar panel configuration to harvest more power from your PV system. These technological work needs more lab research to rooftop solutions. Xandex Solar is extensively working on this power optimization technological research and development to offer a new product that harvests more power from the PV module using the basic logics of electricity in a cost effective approach. National Semiconductor is also working in this area to release their product in the market. Enphase released their micro-inverter product in the market. A few more to come in the near future. These products will additionally benefit our long term investment.
Still most home owners that install Photovoltaic Panels have a certain degree of enthusiasm and willingness to experiment. It’s great to exchange ideas and output rate with likeminded people.
If you have any ideas about how to harvest more solar power from the PV modules or PV system, please post here. That will be more useful for the solar energy users to save some cost.
