How Sunlight Saves Disaster Victims
When natural disasters strike, the most desperate needs are for shelter, food and water. The disruption of electric services hamper relief efforts, expose victims to harsh environmental conditions and prevent hospitals and catering facilities from providing much-needed assistance to the population.
Water is the most urgent need and the team at MIT’s Space and Robotics Lab has come up with a prototype for a solar powered desalination unit. The device utilizes photovoltaic cells to power reverse osmosis pumps. These push water through a permeable membrane to remove impurities, salt and other minerals from sea water, and produce 80 gallons of fresh drinking water a day. The team plans to build a larger unit capable of increasing output to 1 000 liters a day. This unit can be used in disaster relief operations and also in areas which are remote enough to make provisions of water and electricity logistically challenging. A C-130 Cargo plane can transport up to a dozen of the larger units, providing water to 10 000 people.
In the past, diesel generators have been used to provide temporary electricity to disaster survivors, but these pose several problems. Generators are cumbersome and difficult to transport, especially to areas where roads, rail and bridges have been damaged. Generators require fossil fuel and produce large amounts of noise and air pollution. Improper use by inexperienced personnel has resulted in burns, fuel spills, fires, explosions and even asphyxiation. Transporting incendiary fuels during a disaster can be difficult at best.
Solar provides a good alternative. However, PV cells are fragile and break easily, making transport problematic. They also require experienced technicians to orient and assemble the panels, wiring and inverter while monitoring loads on the system. Enter stage left; the portable solar generator. These systems expedite the establishment of services to disaster stricken areas. Portable solar generators are self-contained and new developments in battery technology (deep cycle silicone batteries) ensure that they can operate for extended time periods, in extreme weather conditions, and unlike lead-acid batteries, they are environmentally friendly. If the terrain permits transportation, the trailer can charge while traveling. Alternatively, it can be airlifted to remote or cut-off areas. The trailer also provides room to transport supplies and provisions. Once it arrives on the scene, the portable solar generator is easy to set up and requires no expertise to run up to 3, 500 watt loads.
So you’ve been thinking about generating your own power and taking your home or cottage off “the grid”? Or taking advantage of the government incentives and making some money with the Ontario microFIT program? Either way, there are a few things to consider before you add a solar power system to your home.
Here’s a short guide to what you’ll need to get those solar panels from being just a good idea to an installed power-generating (and moneymaking) part of your home.
First you need to understand what solar panels (photovoltaic or PV panels) are – and aren’t. They aren’t simply plug-in play. There’s no extension cable where you can plug them directly into your house to power your appliances. They require installation, just like your other electrical equipment, or house plumbing. As well, they need other components to do their job, because by themselves they can’t work in a home. To understand this better we need to understand how solar cells, the pattern on the panels which are typically blue and sometimes black, work.
Obviously, a solar cell works from the sunlight hitting it, which causes electricity to flow. However, that electricity differs from your household current in three major ways. Firstly, solar panels are low voltage, typically 35-55 volt, and so solar cells have to be joined together to get that voltage higher. As well, the voltage is irregular. Whereas your house voltage is constantly around 120 volts, a solar cell generates more in the strong sun, and less in the shade (and of course nothing at night). Thirdly, a solar cell’s power is DC, or Direct Current. That means all the power flows in one direction in the wire, witch is different from a home’s AC, or Alternating Current.
So much of solar power installs will not be just the solar panels, but devices to solve these three problems. For example, you’ll use a battery to provide power in off times; of course, if you are connected to an electric utility through the Ontario MicroFIT or FIT programs, referred as “on the grid”, then you may not need batteries, since you can put your excess power “out there” for others to use, and end up making some money. However, if you’re on your own (such as a cottage), then you’ll need deep cycle batteries to keep your lights going at night.
Another device you’ll need with your batteries is a battery charge regulator, also known as a charge controller, which makes sure the batteries are charged and discharged properly to avoid problems, such as shortened battery life (and of course, if you don’t use batteries, you won’t need this device).
Finally, the DC current, whether from the solar cells or from the storage batteries, needs to be converted to AC. If you’ve seen anything about electricity, you’ve seen what is called a sine wave, like the ripples in water when a pebble goes in. DC is like a quiet lake. So another device, the inverter, not only creates those waves, turning the DC into AC, but it can make those waves nice curved sine wave shapes, which is better for appliances using the power. It also makes sure the rate is 60 cycles a second, which we in North America expect from our power lines. Once that’s done, it’s good to go, whether into our home, or onto the grid.
So knowing the components, what else needs to be done? Specific installation will require specific things – for example, you’ll need the roof reinforced if you’re planning a lot of solar panels and your roof isn’t up to code. However, at about 50 pounds a panel, most normal roofs can handle the load. Different types of roofs will require different supports (a shingle roof versus a metal roof, for example). It’s also important to analyze your roof for the ideal place for the panels. If you have nearby trees or objects that might block the panels, consider another location or you might want to have a shade analysis, or move the obstruction. Aiming the cells properly can mean a big difference in power generation. For example, if you have a flat roof, you will have to use a solar panel rack that is designed to angle the panels in just the right position to better face the sun.
As well, you’ll also need a place for the support equipment your solar panels will need. A wall in the garage will likely do for the inverter, but not for the batteries if you use them. Depending on the battery type, you may require good ventilation, since some of them can give off hydrogen gas, which is dangerous in enclosed spaces. As well, batteries work poorly at too hot or too cold a temperature, so an unheated garage in Canadian winters is a definite no-no for them!
Eventually you’ll meet with a contractor or reputable solar installers and go over the details of your specific install. While each one will be different, the preliminary work you do beforehand will make their job easier – and could save you money. Additionally, by planning ahead of time, you’ll be aware of what you’ll need and what you won’t (like batteries if you are connected to a grid).
Solar energy is getting bigger, and it’s here to stay. It’s a great way to lower your energy costs, and it helps prevent further damage to our ecosystem. Adding solar panels to your home is not only ecologically sound, it’s also a boost to your resale value – and that’s yet one more reason to make the move to solar!