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Solar Power Overview
Solar Power can be a great solution for all your power needs if you live without mains electric or can be used to reduce your electricity bills considerably. With a grid connected system you can even sell power back to the electric company!
Solar Electric systems are actually quite simple. A Photovoltaic or "PV" Module is used to charge batteries (much like your car alternator charges the battery in your car). A charge control, similar to a car voltage regulator keeps the battery(s) from overcharging. The stored electricity can be used when it is needed for lights, TV, radio, appliances, pumping and more. Many 12 volt lights, appliances and such are available at RV dealers and caravan suppliers. We have found over the years that the most important thing about Photovoltaic systems is for people to know the status of their batteries. The regulator gives the state of charge of the battery bank with a remote display is often the best solution.
The systems can be all DC electricity, or you can add an inverter which converts DC electricity to AC or electricity to run regular appliances and lights. Most people use an inverter for the convenience of using AC appliances, which are readily available and usually less expensive than equivalent DC counterparts.
Photovoltaic equipment is also widely known as P.V. or solar electricity. P.V. is the high tech side of the solar industry. The diagram below shows common terminology for panels.
The basic building block of photovoltaics is the cell. Cells are either round or square and convert sunlight to D.C. electricity. The photons of light cause electrons to flow in the cell which is usually made of a doped silicon crystal. Each cell produces about 1/2 a volt of electricity under load. The current produced by each cell depends on its size.
Most cells manufactured today produce from two to four amps of current. Cells are normally wired together to form a module or panel. If the cells are wired in series negative (-) to positive (+) etc. the voltage of the module increases. If 33 two amp cells are wired together in series the module will be about 16 1/2 volts at 2 amps or 33 watts (Volts x Amps = Watts).
Modules are usually wired to produce from 14 1/2 to 17 volts on a 12v system. These are called 12 volt modules because they are used to charge 12 volt batteries. A 12 volt lead acid battery is fully charged at about 13 1/2 volts and the module must produce a higher voltage than 12 volts to fully charge the battery. 24v systems will produce up to 28 volts, and the regulators will switch off the charge from the panels at voltages above 28-32v depending on model and manufacturer.
Two or more modules is called an array. Modules, like the cells that they contain, may also be wired in series, parallel or both. How cells and modules are wired give a designer a wide range of voltage and amperage outputs. The majority of applications in smaller projects are for 12 to 24 volt outputs with the amperage depending on how much power is required.
Although the photovoltaic effect was discovered over a hundred years ago, due to low outputs and extremely high costs, applications for Photovoltaics didn't get going until the space program. Satellites in earth orbits or deep space required a source of energy to power their transmitters and other equipment. Photovoltaics, regardless of cost were the only viable option available to NASA engineers. The fruits of the space pioneer's development are harvested today in applications such as remote communications, powering homes, pumping water, charging R.V. batteries and remote lighting.
Layout of Typical Solar Power system
Charge controller, or Regulator Back to Top
If an application needs power available at night, lighting for example, batteries and a charge control are necessary to store the electricity. Charge controls keep batteries from damage through over voltage. The charge control cuts the power to the batteries when full charge is achieved. It is a must on all systems. If the battery storage capacity is more than fifty times the P.V. daily output a charge control is not necessary.
Batteries Back to Top
Batteries used with photovoltaic modules should always be deep cycle batteries. Deep cycle batteries are manufactured to be able to discharge most of their stored energy hundreds of times without damage. Shallow cycle (car batteries) are made to discharge only 10 to 20% of their energy (starting the car) each cycle. Deep discharging a shallow cycle battery even twenty to thirty times will shorten its life if not destroy it. We recommend that you use only deep cycle batteries with P.V. systems: 2 volt solar batteries are a true deep cycle battery with good availability and are normally the best option for your system.
Inverters Back to Top
There are two types of inverters that you should consider in any alternative energy system. A modified sine wave inverter is a good choice for stand alone remote power systems. You should be aware that modified sine wave inverters can produce electronic "noise" in some devices like televisions and stereos. This is not always the case but it can happen as the quality of the electricity is not as "pure" as utility supplied electricity. This "noise" is not predictable since it occurs with some devices using some inverters and not with others.
Pure sine wave inverters produce power that virtually indistinguishable from the utility supplied power, and if using televisions or stereos, this is what we would install and recommend. If you wish to connect into a utility grid, most utilities require that the true sine wave inverter be of a "non islanding" type. This type of inverter will immediately shut down if the grid power is interrupted for any reason, although in Spain , it is illegal to have any battery or capacitor storage when operating a grid connected system. Modified sine wave inverters do not produce a pure enough electrical output to be connected to the electrical grid. They are used in stand alone or utility backup systems only.
Solar Collector position and location Back to Top
There are a number of things to consider when trying to determine if a solar electricity system is right for your house. Is there a large, sunny roof or open area available for mounting the Solar Panels? Does the area have sunlight for at least 8 hours a day? Is it possible to securely anchor the panels on the selected area? (The solar panels can be mounted on a roof, on a deck, on a rack, or on the ground).
Orientation and Tilt of Solar Panels Back to Top
Ideally, solar panels should face due south. However, they can usually be oriented within 15 ° east or west of south with little loss in performance. Some sources even say up to a 45 ° variation is OK, but you will lose some performance.
For summer only electricity, a latitude (41º) less 15 ° . For winter only electricity, use latitude plus 15-20 ° . For year around power, install the panels at 41º latitude which I would recommend, but consider that any variations from these ideals can be compensated for by adding additional collectors.
System Sizing Back to Top
Each system should be sized according to your actual energy requirements. One of the key elements in reducing total system cost is a change in lifestyle. Changing over to Low Energy lamps will save a considerable cost, as will changing to a gas cooker, and possibly gas refrigerator. Making small alterations in our habits can also enable costs to be kept low, such as turning a bulb off as and when you exit the room, turning fans onto low speed, and generally being aware of what power you are using at all times. Often, with being used to having grid powered electricity, we forget that it isn't an endless supply and are rather ruthless with our uses of it.
By doing what is outlined above, a 20kw per day consumption household could be reduced to 15kw or even less. This therefore has a huge impact upon the system requirements in terms of Solar Panel and Wind Turbine quantities, and thus costs.
As the system has to provide less power, it also means the inverter can be smaller, and overall the price of the installation will be hugely reduced, ensuring that you save money as well as the environment!
We recommend the hybrid system as detailed above as it will charge the household batteries during most weather conditions. We normally have high winds during the winter months, so a wind turbine will be the best solution at this time, and we normally have lots of sunshine during the summer months. Therefore, we need to install both items to take advantage of both types of energy we can extract from the environment.
The graph below shows high energy from sunshine in the summer and low in the winter, and high wind energy in the winter and low in the summer
Installation Back to Top
The installation will take place over a pre-decided period. The installation period will depend on the size of the system, but we will not break the installation period once it has been agreed. What this means to you is that at the end of the installation period, you will have a fully operative electricity system.
We will complete any system “works” which we can, away from the installation site in order to minimize any disruption to your grounds, pool and property. All works carried out will be by trained professionals whom you can trust to do the job properly without cutting corners.
Maintenance Back to Top
Solar panels require no maintenance, although we recommend a periodic cleaning and check of function.
The batteries should be checked monthly for any changes in specific gravity and level of fluid in the cells. Daily noting of Regulator and Inverter voltage, input, usage and temperature is wise as it aids diagnosis of problems should they occur by giving you a record of daily conditions. It is important that the voltage stays within the correct voltage for optimum inverter performance. The regulator and windmill electronics will regulate the charge to the batteries, and shut off should it exceed the safe voltage for the system batteries.
We offer an annual maintenance contract consisting of a full system check up, together with a measurement of battery outputs, fluid levels, specific gravity measurements amongst other things. Most of these you are able to complete yourself and we can offer advice and instructions to enable you to do so.
How much will it cost? Back to Top
RibaSolar offer a number of solar friendly items and energy saving systems for your home. To find out what is on offer or to give yourself a rough estimate of cost please click here
Arrange a Site Survey Back to Top
In order for us to compile an accurate and competitive proposal for you, we will need to carry out a site survey. The results from this survey will be used to calculate how much energy will need to be generated and if your property location is suitable.
Please complete the form below to arrange a site survey.
