What is solar power





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	Understanding Solar Power "... Solar Power is an exponentially growing investment that outperforms most other investments available today...." Is solar power the way to go? Solar Power Grid Connection - Case Study Protect and conserve the environment - GREENPEACE, Africa Welcome to Dynamic Demand Misperceptions of solar power There is a general misperception amongst people that solar power is the ultimate, cheep, quick fix for becoming totally independent from traditional grid power like your municipality. A typical misperception is that a few PV panels and "deep-cycle" batteries will be able to sustain i.e. a household. Unfortunately the rules of nature applies - what you put in, is (less) than what you get out. Understanding the basics There is a considerable voltage difference between the PV panels (12 - 30VDC) and that of the appliances (230 or 400VAC). The multiplication factor for i.e. 12V @ 8 Amp to reach 220Volt is mathematically 20 times, which is theoretically the number of PV panels required in series to deliver 8 Amp @ 220Volt. Although we are generating 220VAC from 12Volt DC power sources, must it be realised that the i.e. 8A @ 12VDC, will only deliver (8 Amp ÷ 20 =) 0.4 Amps @ 220V, barely enough to keep a TV going. By applying the above maths it does not matter what kind of PV panel or inverter you use, these basics will always apply. A minimum of 20 x 12V @ 8A PV panels = < 8A @220V A minimum of 8 x 30V @ 8A PV panels = < 8A @220V _____________________________________________________________________________________________________________________________ Types of solar Power Systems Hybrid and Backup Solar Power Systems See our product range <here>. Hybrid systems are a combination between an off-grid system with batteries, which can also take additional power inputs like: Generators Power Wind turbines Some Hybrid-Solar models (as depicted above) can also export electricity into the grid, like Grid-Tied-Inverters do. If an alternative power source is available during after-hours to supplement the solar power (available only during day-time), the number of batteries and PV panels can be reduced substantially, making such a system much more affordable than an Off-Grid solar system. Due to the battery bank, it will however always be more expensive than a Grid-Tied solution. Click <HERE> to see all our Backup and Hybrid Solar Systems _________________________________________ Grid-tied solar Power Systems See our product range <here> The Grid-tied system supplements your electricity supply by producing electricity that you draw from the utility grid and is primarily used to save on electricity bills. This system is capable of pushing unused electricity back into the utility supply for later use (i.e. during night time.) See this video clip (note direction of meter). With grid-tied systems it is required by law that it will disconnect from the grid and switch off to prevent power being pushed back into the grid when there is a power failure on the grid-supply. This is to prevent maintenance people working on the grid of being electrocuted. This is called Anti-Islanding. Click <HERE> to see all our Grid-Tied Solar Systems _______________________________________________________ Off-grid Solar Power Systems See our product range <here> Off-grid systems are mostly used where electricity is crucial where there it is no other source of electricity supply available. It is an expensive method of producing power for "around the clock" use, for the following reasons: It needs to be able to generate ± 5 times! of what is being used during day-time, to allow for sufficient electricity to be available during day-time and stored (in a battery bank) for use during night-time. Less than this will reduce the battery life exponentially or the system will fail to deliver sufficient power. Such systems require a huge number of PV panels to deliver sufficient power to keep the batteries charged optimally. A large capacity battery bank is required that needs to be nurtured. This is the most important component of a solar power system that is mostly misunderstood or misinterpreted. Click <HERE> to see all our Off-Grid Solar Systems Sample configuration of a basic Off-grid Solar System System Configuration for 1.2KW PV System @ <70% capacity for 1 x TV, 1 x fridge and 4 x lights _____________________________________________ Village Solar Systems To meet the growing demand for larger and more complex rural electrification systems, Electrilabs offers a new concept for micro-grids. This concept brings a very robust solution, which is simple to implement while providing flexibility in both its design and management. A standard hybrid unit is at the core of the system and decentralized units can provide redundancy, storage service, power assistance, and interface with other renewable sources to the micro-grid. This concept offers the following advantages : Independence Each decentralized unit is independent from the rest of the system and can supply its own load in case of non-availability of the central unit. Each decentralized unit is also protected against the mal-functioning of other participants of the system if they have excessive energy consumption. Energy and power allocations can be managed for each distributed group. Flexibility Each decentralized unit can add its own power to what is allocated from the central unit. Sharing Each distributed system with its own energy source can share the excess with other participants of the mini-grid on a “share the excess, keep the essential” principle. It also has a given quota of energy available from the mini-grid. Sharing solar power in a village See Brochure See Video Clip Click <HERE> to see all our mini-Grid Solar Systems _____________________________________________________________________________________________________________________________ Anti-Islanding of grid-tied and/or Hybrid Solar Power Systems Please note that legislation dictates that any system that is grid-tied and still capable of generating power when the grid power has failed, MUST present power from being pushed back into the grid while the grid has failed. Many countries (including South Africa) have adapted the international standard DIN VDE 0126-1-1 in terms of the isolation of embedded power plants (grid-tied power generation systems) to prevent the islanding effect. Read more about our Automatic Isolation Unit here. _________________________________________________ Solar Battery Systems A typical battery bank required for a mid-sized solar system of ± 10KW If gel/lead-acid batteries are used then the battery replacement is required every <3 years. The most appropriate batteries to use for solar power are the OPzV or Gel solar batteries which have a life expectancy of 12 - 20 years. Like for all batteries, it needs to be kept at < 25 °C, never overcharged, frequently charged to full capacity and never discharged more than 25 - 30% of it's capacity. If any of these factors are not adhered to, any battery's life will reduce exponentially. Click <HERE> to see all our Battery Systems ____________________________________________________________________________________________________________________________ Fundamentals - Solar radiation One of the basic processes behind the photovoltaic effect, on which the operation of solar cells is based, is generation of the electron-hole pairs due to absorption of visible or other electromagnetic radiation by a semiconductor material. Solar Power yield Sunny day Rainy day Sunny month ____________________________________________________________________________________________________________________________ Tips Selecting an inverter The power of the inverter must be selected according to the way it will be used. The sum of the power of all loads must not exceed the rated power of the inverter. The maximum power of the inverter must be able to cover the starting currents of the loads. In order to allow the connection of more loads, we recommend an oversized inverter. Selecting the PV generator and solar charge controller The solar module array has to be adjusted to the local sunlight conditions and the system‘s energy requirement. In order to avoid stagnation times, the PV generator must also provide enough power during months with little solar radiation in order to cover the requirement of the connected loads. The chosen solar charge controller must also be suitable for the maximum short-circuit current of the PV generator and the maximum load current. In some applications, however, technical properties also play an important role in the choice of solar charge controller. This may mean that a high-performance solar charge controller with corresponding additional functions is used in a system with a low output. In order to keep the initial investment small, we recommend planning the size of the PV generator and battery according to the current energy consumption and choosing a solar charge controller which will allow the system to be expanded later. Selecting the system voltage The power requirement of the loads should be the decisive factor when choosing the system voltage. The higher the power, the higher the system voltage. If no DC loads are connected to the system, a higher system voltage should be chosen in order to reduce the alternating currents, and thus the losses on the DC side. Inverters also generally work more effectively with a higher input voltage. All in all, a higher system voltage leads to the system having a greater efficiency, since losses are reduced Cable lengths and cross sections Direct currents in inverter systems are typically large. For this reason, it is important to dimension the cables between the battery and the inverter appropriately. Always connect the inverter directly to the battery. The cable you use should be as short as possible. In addition, the cable cross section should match the expected flow of current. In case of doubt, a thicker cable should be chosen. This can have a significant influence on the overall behaviour of the system. Using thick and short cables can limit losses and thus allow you to create a system with a better level of efficiency and/or better performance. If the cables on the direct current side of the inverter are included in the delivery, these should not be lengthened, and a smaller cross section should not be used. ____________________________________________________________________________________________________________________________ In-depth Information For detailed information about Safe and Reliable photovoltaic energy generation, click <here>. _____________________________________________________________________________________________________________________________ How important is the Efficiency of an Inverter? Click on picture for a quick slide-show about our 98.4% efficient PLATINUM Inverters _____________________________________________________________________________________________________________________________ Killer loads for (off-grid) solar systems Motors and compressors requires a large amount of current to start. The effect of this high starting demand tends to cause the output voltage of the inverter to drop considerably which could easily cause the inverter to fail to start the motor or compressor. This can also damage the solar inverter or reduce the inverter's life expectancy considerably. Fridges (compressors) and pumps (motors) are therefore often the cause of either great over-sizing of off-grid solar systems OR the main cause of inverter failure. Soft-Starters can greatly decrease these problems by managing the inrush. Soft-Starters are available that provides: Reduction of compressor start-current by up to 40% through a soft-start feature. Provide energy saving of up to 25% Low voltage protection High voltage protection Reduce running costs and extended compressor life. Spike/Surge protection Water splash proof for rugged application Aids compliance with energy efficiency regulations. In-circuit programming – allowing the units to be re-programmed while installed in the field Fridges/Freezers There are three types of solar fridges: ones that use batteries and solar panels, ones that use just solar panels, and ones that use neither batteries nor panels and are constructed from household materials. 1. A solar fridge that uses batteries actually uses a combination of solar panels and lead batteries - the batteries serve as back up overnight and on sunless days. While it can be effective, this type of solar fridge has many disadvantages. For instance, it is expensive to buy and the batteries are heavy and deteriorate quickly in hot climates. It is maintenance intensive and only lasts about three years. The batteries also need to be disposed of properly, otherwise they leak and cause lead pollution. 2. Solar-powered refrigerators that generate electricity with the help of solar panels, then use this electricity like a normal plug-in refrigerator. Although this type of refrigerator is powered by solar energy, it is not 100% eco-friendly as the cooling gases that are used in the refrigerator and the ones generated due to cooling, contribute to global warming and depletion of the ozone layer. 3. Solar-powered fridges that don’t require batteries or solar panels are better suited to developing countries, as they can be made from basic household materials. Although these fridges are technically solar powered, they rely on conduction, convection and evaporation to operate at an even 6°C. These refrigerators work according to atmospheric temperatures - the drop and rise in the heat of the sun directly affects the rate of cooling. The greater the heat of the sun, the lower the temperature will be in the inner cylinder. Many scientists predict that solar-powered refrigerators will totally replace all electricity powered refrigerators as the most energy-efficient refrigerators. _____________________________________________________________________________________________________________________________ Useful links What is "azimuth"? ____________________________________________________________________________________________________________________________ Calculation Tools Inverter sizing Calculators Solar Performance map Sun Location Your area's solar data