Photovoltaics or PV for short convert the photons in sun light to Direct Current (DC) electricity. They are the same as a normal generator but are getting the fuel from the sunlight rather than a petrol can.
When light photons of sufficient energy strike a solar cell, they knock electrons free in the silicon crystal structure forcing them through an external circuit (battery or direct DC load), and then returning them to the other side of the solar cell to start the process all over again. The voltage output from a single crystalline solar cell is about 0.5V with an amperage output that is directly proportional to cell’s surface area (approximately 7A for a 6 inch square multicrystalline solar cell). Typically 30-36 cells are wired in series (+ to -) in each solar module. This produces a solar module with a 12V nominal output (~17V at peak power) that can then be wired in series and/or parallel with other solar modules to form a complete solar array to charge a 12, 24 or 48 volt battery bank.
Some locations are better than others. Each hour of full sun will typically generate about 225 Watts per square meter of panels. You will be generating electricity for all daylight hours but if your roof is shaded for part of the day by hills, or not getting full sun because of clouds, then you will get less Full Sun Hours and therefore less electricity. So, if clouds are blocking 50% of the total power of the sun then you will get one Full Sun Hour out in two hours. Thailand’s full sun hours ranges from about 4.5 in rainy season and 7 in dry season. The average for the South of Thailand is about 5.5 hours.
Irradiance is a measure of the sun’s power available at the surface of the earth and it averages about 1000 watts per square meter. Thailand’s average is about 1700 watts per square meter which just shows how powerful the sun is in Thailand. With typical crystalline solar cell efficiencies around 15%, that means we can expect to generate about 225W per square meter of solar cells placed in full sun. Insolation is a measure of the available energy from the sun and is expressed in terms of “full sun hours” (i.e. 4 full sun hours = 4 hours of sunlight at an irradiance level of 1000 watts per square meter).
No. The inverter requires a constant connection to the grid to operate. For using when there is a powercut you will need a system with battery backup. In Thailand, power cuts can be a major problem, if this is a factor for you, then we recommend going for a battery backup system to keep your essentials running during power cuts.
Maybe. Appliances like electric cookers, high power electric shower units and older and large air conditioners are often not practical on solar.
Running on solar is all about the balance between what you can produce and what you use. To get the best out of any solar system, it pays to be as efficient as possible with your power consumption.
Refrigeration and lighting are typically the largest energy consumers in a and these two areas should be looked at very carefully in terms of getting the most energy efficient units available. In the last 5 years large advances have been made in the efficiency of refrigerators and LED lights are far more efficient and should replace any traditional incandescent bulbs. Relatively small changes can make a big difference.
This is always the first step in creating a quote on any solar system. We will come in a measure exactly what you are using and what would make sense to be changed.
Panels are installed in arrays. The area that can be used and how they look when they are installed both depend on exactly the roof design. Some traditional thai design houses with pyramid roofs do sometimes make it challenging to fit the area. The bulk and therefore the best value panels are rectangular, other shapes can be found but are considerably more expensive.
The inverter takes the DC energy stored coming from the panels and inverts it to 240 VAC to run your AC appliances. Modern inverters usually included all the switches and connectors that are required to connect directly to the panels.
Systems with Battery backup and off-grid systems will also need
The battery bank stores the energy produced by the solar array during the day for use at anytime of day or night. Batteries come in many sizes and grades. The battery bank can be the most costly part of an installation. If planning a backup system, then you can reduce the required size of battery bank by limiting the number and type of appliances.
The two main functions of a charge controller are to prevent the battery from being overcharged and eliminate any reverse current flow from the batteries back to the solar modules at night.
Yes, but it is not the best way. For water heating, a Solar Thermal system is simpler and more efficient. We recommend a Solar Thermal system as a part of a total solution. By reducing the need for electric power showers and hot water heaters, the battery requirement for a PV Solar Installation can be reduced.
Your solar electric system will not produce electricity without direct or diffused sunlight. On cloudy days you will still be generating electricity though not as much as on sunny days. During cloudy days and at night, you can draw electricity from the grid. With a grid-tied system, you build up credits on sunny days and draw from these credits on cloudy days and at night.
This depends on so many factors but usually YES. Systems are improving and prices are reducing making it cost effective for more and more installations all the time.
Electricity prices in Thailand are at the moment about 4 – 5 THB per unit. This is quite a low price compared to Europe and many other parts of the world and are expected to increase over the next few years.
Depending on size and system details you will produce your own electricity with solar for approx. 1.0 – 1.8 THB per unit (kWh) over the lifespan of system (25 Years) . The all-important Breakeven point works out between between 5-11 years ( depending on system size).
Thailand is in the process of creating a ‘feed in’ system where you will be able to sell surplus power to the electricity company. This system is already running successfully in many parts of the world and is expected to be running in Thailand in the not too distant future.
Update June 2018
Energy policymakers gave the green light to start buying solar power generated from private buildings and households once again after postponing the programme for more than four years.
Private buildings and households that are accepted by the programme will sell surplus solar power to the state’s utilities.
Energy Minister Siri Jirapongphan said the Department of Alternative Energy Development and Efficiency is carrying out studies to outline the investment conditions, which are expected to be concluded this year.
He said there is no solid time frame yet because details such as business model, investment budget, power tariff, net metering system, supporting region and capacity from each building are still under development.
The tightened condition is the power tariff to sell back should be up to 1.68 baht per kilowatt-hour.
Mr Siri said policymakers are confident that the cost to develop rooftop solar photovoltaic panels has declined.
The programme will allow for households to sell power either under a business-to-business model or to sell surplus electricity wholesale to the state.
“We are working to support households to participate in the power generation from their own rooftops and to receive revenue from selling the surplus electricity,”
published by: Bangkok Post
There are also many not so obvious benefits to renewable energy. If you suffer from powercuts then you should also take into consideration the downtime that could be saved by having a battery bank to keep things running. If you are a hotel or resort, then you should also consider the marketing potential of being ECO. More and more travellers are becoming sensitive to environmental concerns and in an increasingly competitive market, anything that makes your business stand out will increase your returns.