Tuesday, September 7, 2010
emergency power back up
12 volt power kit every thing included except the battery. $299.00 plus shipping. This will easily light up a room and drive a fan or 12 volt tv.
Sunday, September 5, 2010
solar mounts for small panels
I am testing several ways to mount my solar panels. It seems if you have a big array you are set but us small fry with one or two panels seem to be left to our own devices. I will have some ideas soon.
Joe
Joe
12 volt solar wiring
More neat info from ALTE
Properly sized wire can make the difference between inadequate and full charging of a battery system, between dim and bright lights, and between feeble and full performance of tools and appliances. Designers of low voltage power circuits are often unaware of the implications of voltage drop and wire size.
In conventional home electrical systems (120/240 volts ac), wire is sized primarily for safe amperage carrying capacity (ampacity). The overriding concern is fire safety. In low voltage systems (12, 24, 48VDC) the overriding concern is power loss. Wire must not be sized merely for the ampacity, because there is less tolerance for voltage drop (except for very short runs). For example, at a constant wattage load, a 1V drop from 12V causes 10 times the power loss of a 1V drop from 120V.
Use the following chart as your primary tool in solving wire sizing problems. It replaces many pages of older sizing charts. You can apply it to any working voltage, at any percent voltage drop.
Determining tolerable voltage drop for various electrical loads
A general rule is to size the wire for approximately 2 or 3% drop at typical load. When that turns out to be very expensive, consider some of the following advice. Different electrical circuits have different tolerances for voltage drop.
LIGHTING CIRCUITS, INCANDESCENT AND QUARTZ HALOGEN (QH): Don't cheat on these! A 5% voltage drop causes an approximate 10% loss in light output. This is because the bulb not only receives less power, but the cooler filament drops from white-hot towards red-hot, emitting much less visible light.
LIGHTING CIRCUITS, FLUORESCENT: Voltage drop causes a nearly proportional drop in light output. Flourescents use 1/2 to 1/3 the current of incandescent or QH bulbs for the same light output, so they can use smaller wire. We advocate use of quality fluorescent lights. Buzz, flicker and poor color rendition are eliminated in most of today's compact fluorescents, electronic ballasts and warm or full spectrum tubes.
DC MOTORS may be used in renewable energy systems, especially for water pumps. They operate at 10-50% higher efficiencies than AC motors, and eliminate the costs and losses associated with inverters. DC motors do NOT have excessive power surge demands when starting, unlike AC induction motors. Voltage drop during the starting surge simply results in a "soft start".
AC INDUCTION MOTORS are commonly found in large power tools, appliances and well pumps. They exhibit very high surge demands when starting. Significant voltage drop in these circuits may cause failure to start and possible motor damage. Follow the National Electrical Code. In the case of a well pump, follow the manufacturer's instructions.
PV-DIRECT SOLAR WATER PUMP circuits should be sized not for the nominal voltage (ie. 24V) but for the actual working voltage (in that case approximately 34V). Without a battery to hold the voltage down, the working voltage will be around the peak power point voltage of the PV array.
PV BATTERY CHARGING CIRCUITS are critical because voltage drop can cause a disproportionate loss of charge current. To charge a battery, a generating device must apply a higher voltage than already exists within the battery. That's why most PV modules are made for 16-18V peak power point. A voltage drop greater than 5% will reduce this necessary voltage difference, and can reduce charge current to the battery by a much greater percentage. Our general recommendation here is to size for a 2-3% voltage drop. If you think that the PV array may be expanded in the future, size the wire for future expansion. Your customer will appreciate that when it comes time to add to the array.
WIND GENERATOR CIRCUITS: At most locations, a wind generator produces its full rated current only during occasional windstorms or gusts. If wire sized for low loss is large and very expensive, you may consider sizing for a voltage drop as high as 10% at the rated current. That loss will only occur occasionally, when energy is most abundant. Consult the wind system's instruction manual.
More techniques for cost reduction
ALUMINUM WIRE may be more economical than copper for some main lines. Power companies use it because it is cheaper than copper and lighter in weight, even though a larger size must be used. It is safe when installed to code with AL-rated terminals. You may wish to consider it for long, expensive runs of #2 or larger. The cost difference fluctuates with the metals market. It is stiff and hard to bend, and not rated for submersible pumps.
HIGH VOLTAGE PV MODULES: Consider using higher voltage modules and a MPPT solar charge controller to down convert to the system voltage (e.g. 12, 24 and 48V) to compensate for excessive voltage drop. In some cases of long distance, the increased module cost may be lower than the cost of larger wire.
SOLAR TRACKING: Use a solar tracker (e.g. Zomeworks or Unirac) so that a smaller array can be used, particularly in high summer-use situations (tracking gains the most energy in summer when the sun takes the longest arc through the sky). The smaller PV array will require smaller wire.
WATER WELL PUMPS: Consider a slow-pumping, low power system with a storage tank to accumulate water. This reduces both wire and pipe sizes where long lifts or runs are involved. A PV array-direct pumping system may eliminate a long wire run by using a separate PV array located close to the pump. Many of our solar water pumps are highly efficient DC pumps that are available up to 48V. We also make AC versions and converters to allow use of AC transmitted over great distances. These pumps draw less running current, and far less starting current than conventional AC pumps, thus greatly reducing wire size requirements.
Properly sized wire can make the difference between inadequate and full charging of a battery system, between dim and bright lights, and between feeble and full performance of tools and appliances. Designers of low voltage power circuits are often unaware of the implications of voltage drop and wire size.
In conventional home electrical systems (120/240 volts ac), wire is sized primarily for safe amperage carrying capacity (ampacity). The overriding concern is fire safety. In low voltage systems (12, 24, 48VDC) the overriding concern is power loss. Wire must not be sized merely for the ampacity, because there is less tolerance for voltage drop (except for very short runs). For example, at a constant wattage load, a 1V drop from 12V causes 10 times the power loss of a 1V drop from 120V.
Use the following chart as your primary tool in solving wire sizing problems. It replaces many pages of older sizing charts. You can apply it to any working voltage, at any percent voltage drop.
Determining tolerable voltage drop for various electrical loads
A general rule is to size the wire for approximately 2 or 3% drop at typical load. When that turns out to be very expensive, consider some of the following advice. Different electrical circuits have different tolerances for voltage drop.
LIGHTING CIRCUITS, INCANDESCENT AND QUARTZ HALOGEN (QH): Don't cheat on these! A 5% voltage drop causes an approximate 10% loss in light output. This is because the bulb not only receives less power, but the cooler filament drops from white-hot towards red-hot, emitting much less visible light.
LIGHTING CIRCUITS, FLUORESCENT: Voltage drop causes a nearly proportional drop in light output. Flourescents use 1/2 to 1/3 the current of incandescent or QH bulbs for the same light output, so they can use smaller wire. We advocate use of quality fluorescent lights. Buzz, flicker and poor color rendition are eliminated in most of today's compact fluorescents, electronic ballasts and warm or full spectrum tubes.
DC MOTORS may be used in renewable energy systems, especially for water pumps. They operate at 10-50% higher efficiencies than AC motors, and eliminate the costs and losses associated with inverters. DC motors do NOT have excessive power surge demands when starting, unlike AC induction motors. Voltage drop during the starting surge simply results in a "soft start".
AC INDUCTION MOTORS are commonly found in large power tools, appliances and well pumps. They exhibit very high surge demands when starting. Significant voltage drop in these circuits may cause failure to start and possible motor damage. Follow the National Electrical Code. In the case of a well pump, follow the manufacturer's instructions.
PV-DIRECT SOLAR WATER PUMP circuits should be sized not for the nominal voltage (ie. 24V) but for the actual working voltage (in that case approximately 34V). Without a battery to hold the voltage down, the working voltage will be around the peak power point voltage of the PV array.
PV BATTERY CHARGING CIRCUITS are critical because voltage drop can cause a disproportionate loss of charge current. To charge a battery, a generating device must apply a higher voltage than already exists within the battery. That's why most PV modules are made for 16-18V peak power point. A voltage drop greater than 5% will reduce this necessary voltage difference, and can reduce charge current to the battery by a much greater percentage. Our general recommendation here is to size for a 2-3% voltage drop. If you think that the PV array may be expanded in the future, size the wire for future expansion. Your customer will appreciate that when it comes time to add to the array.
WIND GENERATOR CIRCUITS: At most locations, a wind generator produces its full rated current only during occasional windstorms or gusts. If wire sized for low loss is large and very expensive, you may consider sizing for a voltage drop as high as 10% at the rated current. That loss will only occur occasionally, when energy is most abundant. Consult the wind system's instruction manual.
More techniques for cost reduction
ALUMINUM WIRE may be more economical than copper for some main lines. Power companies use it because it is cheaper than copper and lighter in weight, even though a larger size must be used. It is safe when installed to code with AL-rated terminals. You may wish to consider it for long, expensive runs of #2 or larger. The cost difference fluctuates with the metals market. It is stiff and hard to bend, and not rated for submersible pumps.
HIGH VOLTAGE PV MODULES: Consider using higher voltage modules and a MPPT solar charge controller to down convert to the system voltage (e.g. 12, 24 and 48V) to compensate for excessive voltage drop. In some cases of long distance, the increased module cost may be lower than the cost of larger wire.
SOLAR TRACKING: Use a solar tracker (e.g. Zomeworks or Unirac) so that a smaller array can be used, particularly in high summer-use situations (tracking gains the most energy in summer when the sun takes the longest arc through the sky). The smaller PV array will require smaller wire.
WATER WELL PUMPS: Consider a slow-pumping, low power system with a storage tank to accumulate water. This reduces both wire and pipe sizes where long lifts or runs are involved. A PV array-direct pumping system may eliminate a long wire run by using a separate PV array located close to the pump. Many of our solar water pumps are highly efficient DC pumps that are available up to 48V. We also make AC versions and converters to allow use of AC transmitted over great distances. These pumps draw less running current, and far less starting current than conventional AC pumps, thus greatly reducing wire size requirements.
How do I mount my solar panel?
This is a neat little article from AltE University
How To for Solar Panel Mounting
Solar electric panel arrays for stand-alone systems are installed in many unique and innovative ways. However, there are common issues involved in any installation, whether the array is fixed or tracking, mounted at ground level, or on a pole or building. The array orientation and tilt angle considerations are discussed in the article Solar Panels (Photovoltaic Panels): Overview.
Roof mounting of solar panels that run flush with the roof's surface.
The objective is a solidly mounted solar panel array that will last for many years and withstand all kinds of weather. Regardless of whether you buy or build the mounting structure make sure it is anchored and the modules are restrained. Several manufacturers make mounting structures designed to work with almost any solar panel model. This hardware is intended for multiple applications and different mounting techniques and considerations like wind loading have been included in the design. Using this mounting hardware is the simplest and often the most cost effective. Customized array mounting structures can be expensive. Consider the characteristics of various mounting materials:
* Aluminum - lightweight, strong, and resistant to corrosion. Aluminum angle is an easy material to work with, holes can be drilled with commonly available tools, and the material is compatible with many PV module frames. Aluminum is not easy to weld.
* Angle Iron - easy to work with but corrodes rapidly. Galvanizing will slow corrosion but mounting brackets and bolts will still rust, particularly in a wet environment. The material is readily available and brackets can be welded easily.
* Stainless Steel - expensive and difficult to work with but will last for decades. May be a good investment in salt spray environments.
* Wood - inexpensive, available, and easy to work with but may not withstand the weather for many years--even if treated with preservative. Attaching modules to a wooden frame requires battens or clips to hold them in place.
The foundation for the array should be designed to meet the wind load requirements of the region. Wind load depends on the size of the array and the tilt angle. Ask a local contractor how to anchor your array to withstand the wind expected in your area.
Changing the tilt angle of an array to account for seasonal changes in sun altitude is not required. For mid-latitude locations, a tilt angle change every three months is estimated to increase energy production about 5 percent on an annual basis. For most applications, the additional labor and the added complexity of the array mount does not justify the small increase in energy produced.
Passive solar trackers automatically move solar panels to face directly into the sun without using any electricity.
If tracking of the solar panel array is desired, the recommended trackers are single-axis units that require little control or power. One kind of passive tracker is driven by a closed Freon system that causes the tracker to follow the sun with adequate accuracy for flat-plate PV modules, such as the Zomeworks. In high wind areas a powered tracker may be preferred. Pole mounted trackers that support 4 to 12 PV modules are available and often used for small stand-alone systems, particularly water pumping applications. The tracker manufacturer will provide all the array mounting hardware and instructions for securely installing the tracker. The amount and type of foundation for the pole-mounted tracker depends on the size of the array being supported. Reinforced concrete with anchor bolts is recommended. The foundation and frame should be designed to withstand the worst case wind expected in the area. The movement of the array should be checked to make sure the path is clear of obstructions.
In general, roof mounting of solar panels is more complex than either ground mounting or pole mounting. Roof mounts are more difficult to install and maintain, particularly if the roof orientation and angle are not compatible with the optimum solar array tilt angle. Penetrating the roof seal is inevitable and leaks may occur. Also, it is important to achieve a firm and secure attachment of the array mounting brackets to the roof. Attaching the mounting brackets to the rafters will provide the best foundation, but this may be difficult because module size and rafter spacing are usually not compatible. If there is access to the underside of the roof, 2 x 6-inch blocks can be inserted between the rafters and the attachment made to the blocks. Attaching the array to the plywood sheathing of the roof may result in roof damage, particularly if high winds are likely.
If a roof mount is required, be sure to allow a clear air flow path up the roof under the array. The array will operate cooler and produce more energy if it stands off the roof at least 3 inches. Flush mounting solar panels to the roof of a building is not recommended. The modules are more difficult to test and replace, and the performance of the array is decreased because of the higher operating temperatures.
How To for Solar Panel Mounting
Solar electric panel arrays for stand-alone systems are installed in many unique and innovative ways. However, there are common issues involved in any installation, whether the array is fixed or tracking, mounted at ground level, or on a pole or building. The array orientation and tilt angle considerations are discussed in the article Solar Panels (Photovoltaic Panels): Overview.
Roof mounting of solar panels that run flush with the roof's surface.
The objective is a solidly mounted solar panel array that will last for many years and withstand all kinds of weather. Regardless of whether you buy or build the mounting structure make sure it is anchored and the modules are restrained. Several manufacturers make mounting structures designed to work with almost any solar panel model. This hardware is intended for multiple applications and different mounting techniques and considerations like wind loading have been included in the design. Using this mounting hardware is the simplest and often the most cost effective. Customized array mounting structures can be expensive. Consider the characteristics of various mounting materials:
* Aluminum - lightweight, strong, and resistant to corrosion. Aluminum angle is an easy material to work with, holes can be drilled with commonly available tools, and the material is compatible with many PV module frames. Aluminum is not easy to weld.
* Angle Iron - easy to work with but corrodes rapidly. Galvanizing will slow corrosion but mounting brackets and bolts will still rust, particularly in a wet environment. The material is readily available and brackets can be welded easily.
* Stainless Steel - expensive and difficult to work with but will last for decades. May be a good investment in salt spray environments.
* Wood - inexpensive, available, and easy to work with but may not withstand the weather for many years--even if treated with preservative. Attaching modules to a wooden frame requires battens or clips to hold them in place.
The foundation for the array should be designed to meet the wind load requirements of the region. Wind load depends on the size of the array and the tilt angle. Ask a local contractor how to anchor your array to withstand the wind expected in your area.
Changing the tilt angle of an array to account for seasonal changes in sun altitude is not required. For mid-latitude locations, a tilt angle change every three months is estimated to increase energy production about 5 percent on an annual basis. For most applications, the additional labor and the added complexity of the array mount does not justify the small increase in energy produced.
Passive solar trackers automatically move solar panels to face directly into the sun without using any electricity.
If tracking of the solar panel array is desired, the recommended trackers are single-axis units that require little control or power. One kind of passive tracker is driven by a closed Freon system that causes the tracker to follow the sun with adequate accuracy for flat-plate PV modules, such as the Zomeworks. In high wind areas a powered tracker may be preferred. Pole mounted trackers that support 4 to 12 PV modules are available and often used for small stand-alone systems, particularly water pumping applications. The tracker manufacturer will provide all the array mounting hardware and instructions for securely installing the tracker. The amount and type of foundation for the pole-mounted tracker depends on the size of the array being supported. Reinforced concrete with anchor bolts is recommended. The foundation and frame should be designed to withstand the worst case wind expected in the area. The movement of the array should be checked to make sure the path is clear of obstructions.
In general, roof mounting of solar panels is more complex than either ground mounting or pole mounting. Roof mounts are more difficult to install and maintain, particularly if the roof orientation and angle are not compatible with the optimum solar array tilt angle. Penetrating the roof seal is inevitable and leaks may occur. Also, it is important to achieve a firm and secure attachment of the array mounting brackets to the roof. Attaching the mounting brackets to the rafters will provide the best foundation, but this may be difficult because module size and rafter spacing are usually not compatible. If there is access to the underside of the roof, 2 x 6-inch blocks can be inserted between the rafters and the attachment made to the blocks. Attaching the array to the plywood sheathing of the roof may result in roof damage, particularly if high winds are likely.
If a roof mount is required, be sure to allow a clear air flow path up the roof under the array. The array will operate cooler and produce more energy if it stands off the roof at least 3 inches. Flush mounting solar panels to the roof of a building is not recommended. The modules are more difficult to test and replace, and the performance of the array is decreased because of the higher operating temperatures.
Subscribe to:
Posts (Atom)