What are Solar Panels?

Sep 28
2011

 

Solar panel construction lies at the heart of every solar power system. Also known as the photovoltaic (PV) module, the solar panel is usually square or rectangular in shape, and is where all the magic begins. Without this collector of solar energy, nothing happens. These can be hooked in parallel or used singularly, and come in the form of roof-mounted shingles, a standing-seam roof panel or ground-mounted array. However, one constant exists in all panels, regardless of shape or size, the most effective solar panels are made of silicon.

Here's an excellent nuts and bolts description about solar panel construction:

But while solar panels are the most necessary of all solar components, they are not the smallest or most basic. Solar panel construction actually begins with a much smaller component. That is the 0.5 volt-producing solar cell, which operates with other solar cells in a solar panel to produce different levels of voltage, most commonly 16 to 17 or 32 to 34 volts.

Keep in mind that as much as 80% of your investment will lie in the PV modules themselves, and there are literally hundreds of types available, but rest easy. PV solar panel construction quality is universally exemplary. You can usually get a 20 to 25 year warranty and easily expect at least that many years of trouble free life. However, you may have to shop around to find any, because with the popularity of solar power has tightened inventory levels. Online purchase from a reputable manufacturer will solve this problem.

So no matter what brand you choose, the quality will be high, and the price about the same per volt, so remember that bigger is generally better. PV modules are rated by a strict testing procedure which shows how many watts they produce. When you purchase a higher wattage module, you skip all the wiring and connecting in parallel that is required with several smaller units. The more common modules come in 150 to 250 watt sizes, but there are a few things you need to consider when making your PV module choice.

You have to choose between single crystal or polycrystalline modules or amorphous silicon modules. Amorphous modules work marginally better in areas of low light and fewer sunlight hours available and lose less voltage at higher temperatures than polycrystalline modules, but are usually 30 to 50 per cent larger.

With single crystal or polycrystalline modules, you will get more power per square inch, roughly 10 to 12 watts of energy output per square foot of module area. When you factor in the average U.S. amount of collectable sun per day of 5 hours, each square foot of solar panel construction will yield an average of 50 watt-hours of usable energy.

Solar panel construction also differs between the two types of PV modules. Polycrystalline modules usually have aluminum frames and tempered glass top covers. These are the most efficient, delivering the most watts per sq foot. Amorphous silicon modules require up to 50 percent as much surface area to deliver the same power, as mentioned above, but can be made of materials other than glass, rendering them unbreakable.

The Uni-Solar corporation has a line of amorphous modules that actually become the roof, rather than sitting on top of it. Their “peel and stick” models apply directly to commercial membranes or standing seam metal roof pans, and if you can attach to the pan before it is installed, they are much easier to handle and install. These versatile modules are thief and hurricane-proof, and the tossed rock from the neighborhood hooligans bounces harmlessly away. There is no increased cost of installation for all these benefits, only the size issue.

There have more recently even been some manufacturers that have harnessed the awesome heat-collecting properties of ceramic tiles and weaved cutting-edge PV modules into them for more attractive, less obtrusive brown and orange designs that are aesthetically appealing.

Solar panel construction is generally universal when it comes to mounting the panels. Extruded aluminum mounting rails come in different pre-cut lengths with multi-position slots to accept any number of module sizes and rafter and joist spans. Leg hardware is then added as it is needed.

Roof attachment is usually accomplished with roof-penetrating waterproofed standoffs with protective flashing that every roofing contractor understands, should you decide to employ professionals for installation. The common asphalt shingle makes the expensive standoffs optional, and solar panel construction skips this worry altogether when you employ ground-mounted systems that use the same mounting rails, but use built-up legs of pipe or other materials.

Solar Hot Water Systems

Sep 12
2011

 

Do you want to know a clean way to heat water? Why not put a solar hot water heater to work. It’s really not complicated. Just expose water to sunlight and voila - you have a non-polluting, efficient solution. I know this sounds simple and I promise I’ll elaborate – but first a little background info. As a DIY'er, solar water heating is much easier than generating electricity and is a more cost effective use of solar power. There are many types of heating systems available even a solar power pool heater that can save you big bucks.

You should know that there are really only three solar water heating systems that have been proven performers throughout the years. But all in all a solar panel water heater is a great solution in many ways. Even if you plan to install a full scale home solar system isolating the water heater portion is smart and economical. If you can heat the water with solar power (through the sun's rays), you'll save enough money on your power bills to get a better ROI (return on investment) for your home solar power system .

If you live in a cold climate you'll need an active anti-freeze system, and closed loop systems are probably your best choice. Now-a-days most solar based homes have the drainback solar water heater as a heating solution. If you're lucky enough to be living in a mild climate then you'll need a completely different type of heater. The best application for warm temperature climates is the something called an Integral Collector System. These are typically less expensive than their cold weather counterparts.

The solar power collectors of your solar hot water heater are mounted on the roof. They are used to heat an anti-freeze fluid like Ethylene Glycol. This heater uses an exchanger to transfer heat from anti-freeze to the water. A temperature sensor is integrated which checks the temperature of the fluid and the warm water in the tank. With the anti-freeze liquid heated up, the pump is turned on to circulate the hot fluid. To make the system fail-safe there should be a backup means of heating provided so the water can be heated through traditional alternatives like gas or electricity.

The mounting of flat-collectors in the solar panel water heater is not important with regard to the distance from the exchanger making it suitable for almost any configuration. The best feature of a closed-loop solar hot water heater is that the pipes are filled with the anti-freeze so the pump does need not to generate a lot of pressure. Other solar heating systems like the drain back system put a lot more strain on the pumps because they would need to overcome the head pressure.

Due to the lower capacity pumps, you can power them with solar panels easily. The low capacity means that you do not require a lot of energy to activate them and this low power can be generated using PV panels. Of course, at night this system will not work, but who needs hot water at night anyway?

While the closed loop kits are readily available and simple to install, there are some challenges. If you do not fill the pipes properly with the fluid, you will get inefficient performance. If you plan to do it yourself, you need to take care to ensure the pipes are completely full with the liquid. There should not be any air pockets.

A solar power hot water heater system comes with a limitation, i.e. the antifreeze fluids deteriorates with time. Once overheated, the efficiency of the antifreeze liquids degrades and some of its by-products get deposited on the interior walls of the pipes of the collector. If you have an efficient system and do your maintenance, you should only need to replace the glycol solution once every decade. To do this properly you should get professional help when replacing the glycol in your solar power heater.

When there is strong sunlight the fluid in the closed-loop will need to be circulating at all times to prevent it from overheating. This will not only ensure a constant supply of hot water but will also help prolong the glycol's life. The use of a tempering valve is important in this case - you don't want that water to get too hot! The piping should be made of copper – as it’s the only material that works well at high temperatures.

Editor Note: These systems can also be used for a solar pool heater. We all know how expensive it is to heat a pool! The truth is that if you live in a multi-season region and use this economical solar heating system you'll extend your pool season by several months. They come as kits a or as a DIY project where you can save yourself some cash.