How to Live Sustainably With Solar Energy (Solar Photovoltaic / P.V. Electric Power) |
How to Live Sustainably With Solar Energy (Solar Photovoltaic / P.V. Electric Power)
originated by:Tipsy
Solar energy is an easy-to-use, generally safe, clean, and renewable resource. Here's how to make the most of it for living off the grid, in a developing country, or even outside.
This article focuses on using solar energy for electricity, which can be used to perform all kinds of work. For heating, including space heating, water heating and cooking, it is generally much simpler and cheaper to collect the sun's heat directly, or, in some cases, overall better to use other energy sources frugally.
Steps
1 Create a Budget. Solar power generally has a high up-front (capital) cost and--if it works--saves money over time (low operating cost). If you estimate that your solar project will cost a large part of your monthly income, or more, make a budget for your overall expenses and project expenses to make sure the project won't cause great financial hardship even if for some unknown reason it turns out to be a total loss.
Solar energy can save a lot of money compared to crude or inefficiently delivered or used sources of energy such as lamp oil. It can also make you a lot of money by helping you read and learn to be more productive, or work with power tools rather than hand tools. Don't take these savings and additional income into account in deciding whether you can afford solar energy, since something might go wrong. But, once you find you can afford the system, take them into account to decide whether it would be a good idea, bearing in mind they may not turn out exactly as you expected.
2 Decide whether you want a solar-powered device, or a system. A stand-alone solar-powered device, such as a solar lantern, rechargeable lamp, or dedicated cell phone charger, is individually cheaper, more portable, does not require skilled installation, and, being self-contained, is less likely to require repair. A system with separate components (which may be bought as a kit chosen to work well together) is cheaper and more effective in the long run because it allows many devices to share a common pool of the expensive solar cells and batteries, and because there are many more suppliers competing on quality and price for ordinary appliances and large solar energy components than on individual stand-alone solar gadgets.
Some standalone devices incorporate a few functions, such as a lantern, radio, and cell-phone charging outlet.
If you don't have any experience with solar energy, try a simple, low-powered but good quality standalone device such as a lantern to see how you like it and understand the basic principles of operation.
If crime is a problem in your area, bear in mind that a stand-alone device--part or all of which must often be at a window or outside to charge--is a more tempting target for a petty thief, but a more-valuable system (or components such as panels) could be vulnerable to organized thieves.
3 Understand the basic components of a solar power system.
Solar cells, organized as and protected in solar panels. These are the flat devices that convert light into electricity. The cells generally produce a constant voltage, but current varying continually with the amount of light; the panels' voltage and wattage (power output, under good conditions) depends on how the cells are arranged in them. This uneven power is not very useful for operating other devices on its own, and could even damage them, so it should be fed to a....
Charge controller. A charge controller is a system of electronic components that smooths out the flow of electricity from the solar panels to, and regulates the discharge of electricity for use from a...
Battery. A battery is a set of galvanic cells which stores electricity. (Colloquially, the term can refer to a single cell, such as an AA battery, or a set of many, such as a 9-volt battery or car battery; a solar-power system usually uses multiple cells for increased voltage more practical for the other components to handle.) A solar power system uses rechargeable batteries for a store of energy to avoid interruptions and to provide electricity when sun is not available or a lot of energy, stored over time, is needed for a short time. Power can be drawn directly from the batteries (or, better, through the charge controller, which regulates their discharge to protect them). But it can be converted from usually low-voltage direct current from the batteries into higher-voltage (usually 120 or 240 volt) alternating current suitable for mass-market, typically inexpensive and good, appliances with an...
Inverter. An "inverter" is a system of electronic components that converts direct current into alternating current, and typically incorporates a system to raise the voltage, too. An inverter may be combined with a charge controller as a single unit. From the inverter (if not directly from the batteries or charge controller), power flows to the...
Appliances, the lights, electronics, tools, gadgets, and so forth you want to run. It gets there through...
Wiring. Choose a kind appropriate for the voltage and current involved. If you have a simple system with only a few dedicated devices such as low-voltage lights, they may be connected directly to the wires. Otherwise, for a variety of appliances, you'll want...
Outlets, switches and other miscellaneous electrical components. Your system will be most versatile and inexpensive to expand if the voltage and connector type is that generally used for appliances in your area. The electricity is just electricity, not very different from that made in other ways; common principles of electrical installation and maintenance and installation apply. In case any of this goes wrong, you'll be glad you had...
Circuit breakers or, less conveniently, fuses and other fail-safe devices such as thermal overload protection in major components such as the charge controller or fusebox. These cut off power or even sacrifice themselves to help prevent electrical problems from escalating into fires. If consumable devices such as fuses are used, make sure spares are on hand and available.
4 Decide what attributes are most important to your solar power system. There are trade-offs involved.
Simplicity. A single unit or all-inclusive kit with detailed instructions would be good if additional components or good technicians are not readily available in your area.
Service life. Although all quality solar equipment should be fairly long-lived, extra-long-lasting equipment, like simple equipment, is well suited to inaccessible areas where getting things, rather than just their own cost, is a major cost or difficulty. (This problem can be mitigated by keeping a stock of spare parts that do not go bad on their own, such as light bulbs or outlets, but that doesn't work for parts that decay whether or not used, such as batteries.)
If you are in a relatively inaccessible area, a return policy or warranty is not a great substitute for consistent high quality often indicated by a good reputation, because getting the "free" service or replacement will be difficult.
Durability. If you don't live in a sturdy, weather-sealed house, or will leave an entire device out to charge, make sure all components are appropriately protected against moisture or exposure to weather with seals and, where appropriate, drain holes. (This is easiest with more-integrated components or standalone devices.) If your area has a crime problem, check that exterior components in particular, including a standalone device itself or its removeable charging panel if considered valuable in your area, can be mounted securely somewhere relatively inaccessible (such as a high roof) and are made of tough, vandal-resistant components (for instance, having extra-strong glass or clear plastic over panels).
Capacity. Bigger, more expensive system components can make, store and deliver more electricity. Adding more power to a particular task often has diminishing returns: for instance, bigger light bulbs make a more pleasing ambience though they may not make simple tasks much more efficient. But more power also lets one do new and very useful additional kinds of tasks, such as operate a computer, power tools or even a Microwave.
Efficiency. More efficient appliances do more with a given amount of electricity. Sunlight itself is free, but the solar power equipment with which to process makes each unit of energy cost overall significantly more than that provided by most electric utilities, so efficiency is important.
5 Choose system components that meet your current needs and make the best use of each other. The cheaper parts, such as the batteries, should have enough capacity to make full use of the more-expensive parts, such as the solar cells. If you're buying an all-in-one device, check that the compromises its components reflect are reasonable: any missing capabilities or reduced durability should be acceptable and compensated for with a significantly lower price and/or (if convenience is important) weight.
Avoid vendor lock-in.[1] Make sure major system components follow design and compatibility standards not limited by any particular manufacturer. For instance, they should work at voltages and with connection types many charge controllers and appliances accept.
6 Choose solar panels. There are several types of solar cells that vary in efficiency per unit area and tendency to decay over time. But, unless you're buying so many that having enough space for them is a concern, it's generally more important that the assembled panels be durable (since they will be out in the rain), have a good price per watt (rate of electricity production).
Check that the solar panel on an all-in-one device has sufficient capacity. Because solar panels are expensive manufacturers may skimp on them. A single day's charging should suffice for all you might want to do with the device in a day, such as run a light for four hours and also, if the device has a phone charger attached, charge the phone once.
7 Choose an appropriate battery. Their capacity is measured in watt-hours; for instance, a 100 watt-hour battery can accept 5 watts for 20 hours to charge it (or a little more, due to losses) and then release 25 watts for four hours for use. Large systems often use multiple batteries in parallel. There are many different kinds, with markedly different characteristics -- unlike with solar panels, this isn't just a matter of power per unit of size or money. The battery should be at least big enough to hold a full day's charge from the solar panels; more, if you want to be able to miss a sunny day and still use the system or device fully. Batteries should not be charged too fast; check that the batteries over which the energy from your solar panels will be spread can handle their maximum charging rate.
Lead-acid batteries are inexpensive for their capacity and durable but not suitable for portable devices because they are filled with dangerous acid. Some need to be "topped off" with water from time to time.
Don't use ordinary car ("starting") batteries. Deep-cycle batteries, some of which are used for trolling motors and RVs, are the kind of lead-acid battery to use for solar power, since they are built for repeated substantial discharge rather than brief large engine-starting bursts only.
Sealed lead-acid "gel cell" batteries are sealed, with the acid inside contained within material to reduce hazards even if they do break. They are inexpensive for their capacity, though not quite so inexpensive as regular lead-acid batteries. They are also relatively heavy compared to non-lead-acid batteries.
Lead-acid batteries can be damaged by excessive discharging, overcharging, or leaving in the discharged state. The charge controller should prevent overcharging and over-deep discharging; portable devices should be recharged promptly after use.
Most batteries should be recharged promptly after any use. Nickel-cadmium batteries, which are obsolete for most uses, are the kind that was important to discharge before recharging.
Nickel-metal-hydride (NiMH) batteries are sealed, durable, and relatively safe generally. They are more expensive and lighter than lead-acid per unit of energy stored, so they are good for portable devices. They are available in standard "AAA", "AA", "C" and "D" sizes, so, if you have a solar power system, you don't need portable solar-powered gadgets too, just a much-cheaper charger and batteries.
Most NiMH batteries run down on their own within a month even if not used; "low-self-discharge" ones take a year or more to.
Check that standard-size rechargeable batteries bigger than AA, such as C and D size, have commensurately larger capacity ratings of several thousand mAH or are cheap and sufficient for your needs. Some are AA cells in larger cases.
Lithium-ion batteries are very light and expensive for their capacity, and mainly suited to expensive portable devices like laptops.
8 Choose a charge controller. The charge controller should be compatible with the particular chemistry (lead-acid, gel cell, NiMH, etc.), capacity, and number of batteries you're using. You may want one that is suitable for the batteries you now have, and a few more also, because the charge controller is relatively inexpensive and durable and room to grow is convenient.
Some important features are protection against overcharging, deep discharge, and excessive rate of charge and discharge.
It's generally safe to assume that an all-in-one device has an acceptable general type of charge controller and that the other components can't charge or discharge the battery too quickly, but deep discharge protection is important for a device with a lead acid (including gel cell) battery.
9 Choose an inverter (for a power system only). Check the wave form type it produces; "true sine wave" (a smooth wave, like a mechanical generator makes) is better for most devices, particularly sensitive electronics, than "modified sine wave", which risks damaging some; no other wave form is appropriate. The capacity should suffice for everything you might want to run from it at once; generous capacity is relatively inexpensive and not harmful.
10 Learn a lot about electrical wiring or find a good electrician, preferably familiar with solar power or at least very smart, to install all the parts of a power system for you. Electricity is complicated, so even if you're doing a solar-power project yourself, it's best to run your plans by someone knowledgeable first.
11 Choose some appliances.
Lamps: Fluorescent tubes or compact fluorescents are efficient, inexpensive, long-lived and powerful. LEDs are too, and physically durable but very expensive in high capacity so they are best for flashlights, lanterns and similarly small lights. Make the best use of them with reflectors and prismatic diffusers, not shades.
Computer: A laptop is generally best because it and its screen consumes very little power. An old, cheap one can is not very expensive, and can run basic software just fine. (Its own battery may go bad with age, but that doesn't matter if it's just being left plugged in.)
Laptops are not very well cooled -- clean the vents regularly.
If computers and Internet connections are uncommon in your area, you could Set up an Internet Cafe.
Power tools: rechargeable ones (charge their batteries from your power system) use little power and their charging process does not draw power very fast, making them particularly good for a small solar power system.
TV: If you must have one, get an LCD TV for low power consumption.
Tips
Follow applicable electrical codes (or, if you don't have any, accepted best practices) when installing wiring.
In some areas electric utilities will, by means of additional equipment, buy surplus solar power you generate. But a modern utility can generate electricity very inexpensively and fairly efficiently (in terms not only of the power-generating fuel itself, but of labor, installation and maintenance, and related energy use) that if grid electricity is available it's normally better to just use that, but conserve it, and choose to have your utility have your share of electricity generated from renewable sources (which might cost a little extra).
Use the Internet for informal reviews and formal tests of solar equipment, general views on suppliers' reputations, to ask manufacturers, resellers and others about devices' capabilities and uses, and to find suppliers of components and complete systems (often made by small companies which may not have established distribution chains but may be flexible and creative with retail or small wholesale orders).
If you are in a poor country a charitable or government development organization might help you pay for and/or install a solar power system.
Warnings
Master Do It Yourself Electrical Safety. Electricity can be dangerous, even, under some circumstances, at voltages much lower than the 120 or 240 volts common for grid-delivered electricity. Some components of an overall low-voltage can create, use, and store high voltage.
Work Safely With Chemicals. Batteries, especially lead-acid ones, can contain dangerous chemicals.
Some batteries produce hydrogen gas when charging, and should be kept in a well-ventilated area.
Dispose of Hazardous Waste, in particular nickel-cadmium and lead-acid batteries properly, preferably by recycling. A recycler may even pay for them.
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