Frequently asked Questions
Renewable Energy (RE) may seem puzzling to some people that are not familiar with it. To help those of you that are being exposed to solar and wind power for the first time, we have compiled a dozen of the most frequently asked questions (with their answers) that we hear every day. We hope this FAQ file is helpful to you.
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 photovoltaic effect produces a flow of electrons. Electrons in the solar cell are excited by particles of light and find the attached electrical circuit the easiest path to travel from one side of the solar cell to the other. The solar cell merely takes a percentage of these electrons and directs them to flow in a path. This flow of electrons is, by definition, electricity.
Solar energy is universal and will work virtually anywhere, however some locations are better than others. 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. With typical crystalline solar cell efficiencies around 14-16%, that means we can expect to generate about 140-160W 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). Obviously different parts of the world receive more sunlight from others, so they will have more “full sun hours” per day.
Unfortunately there is no per square meter “average” since the cost of a system actually depends on your daily energy usage and how many full sun hours you receive per day. A load audit helps us to together determine what your usage patterns and habits are, which in turn helps with the design process.
There are basically three configurations available: Grid-tie which are connected to the existing utility/mains; Grid-tie with battery back-up (operating like the conventional uninterrupted power supplies) and Standalone solar systems. They vary depending on the available systems on site. Other than safety disconnects, mounting structures and wiring a grid-tie system is just solar modules and a grid-tie inverter. You use the utility when available and operate on solar when available too. Grid-tie with battery backup have stand by batteries, which feed the loads in the home when the utility mains are disconnected. The batteries are recharged anytime the utility supply is restored. The last system is the Stand-alone. As the name implies it is totally independent of the utility mains and has the backup batteries also, depending on the expected number of days of insufficient insolation days. This varies from place to place.
There are many components that make up a complete solar system, but the 4 main items are: solar modules, charge controller(s), batteries and inverter(s). The solar modules are physically mounted on a mount structure and the DC power they produce is wired through a charge controller before it goes on to the battery bank where it is stored. 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. 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 inverter takes the DC energy stored in the battery bank and inverts it to 240V(ac) to run your AC appliances.
There are two basic types of mount structures: roof-mounted and ground/pole-mounted systems, each having its own pros and cons. For example, roof mount structures typically keep the wire run distances between the solar array and battery bank to a minimum, which is good. They have good aesthetic value, minimize additional space for panels, and require roof penetrations in multiple locations. The possibilities of roof leakages are prevented by proper and adequate use of sealants. They also need carefully installed ground fault protection. However, on roof-mounted systems, routine maintenance or cleaning of the panels becomes more tasking to achieve due to accessibility issues. On the other hand, ground-mounted solar arrays require a fairly precise foundation set up and are more susceptible to theft /vandalism but are far easier to perform routine maintenance and physical inspection of joints and cables. What method will be used can best be determined after site inspection.
If your site is in the Northern Hemisphere you need to aim your solar modules in the true south direction (as in Nigeria) to maximize your daily energy output. The solar modules should be tilted up from horizontal to get a better angle at the sun and help keep the modules clean by shedding rain/cleaning dust. For the best year-round power output with the least amount of maintenance, you should set the solar array facing true south at a tilt angle equal to your latitude with respect to the horizontal position. The reverse is the case if your location is in the southern hemisphere. Also, panels may be placed on the east-west axis if ideal locations are not available. The system components will now be selected to maximize the reduced captured insolation at such angles.
solar water pumping
Photovoltaics, or solar electric cells, convert sunlight directly into electricity. This electricity is collected by the wiring in the module, then supplied to the DC pump controller and motor, which, in turn, pumps water whenever the sun shines. At night, or in heavy cloud conditions, electrical production and pumping ceases.
Solar pumping systems work anywhere the sun shines. Virtually everywhere in Nigeria enjoys plenty of sun to operate a pumping system economically. The intensity of light varies greatly throughout the day. Morning and afternoon sunlight is less intense because it is entering the earth’s atmosphere at a high angle and passing through a greater cross section of atmosphere, which reflects and absorbs a portion of the light.
The sunlight or insolation levels also vary seasonally. Fortunately, most needs for water correspond with the sunniest seasons of the year – dry season. Small to medium solar electric pumping systems are easily portable. By mounting the solar system on an axle or trailer, a system can be moved from well to well. This increases the economic return of a system by increasing the seasons of use. It may also correspond with the rotation of grazing areas.
The economy and reliability of solar electric power make it an excellent choice for remote water pumping for irrigation and livestock farmers. Their water sources are spread over many miles of rangeland where power lines are few and refueling and maintenance costs are substantial for generator use. A solar pump minimizes future costs and uncertainties. The fuel is free. Moving parts are reduced to as few as one. A few spare parts can assure you many years of reliable water supply at near-zero operating costs. Solar power and water pumping are a natural partnership. Generally, water is needed most when the sun shines its brightest. Solar modules generate maximum power in full sun conditions when we typically need larger quantities of water. Because of this “sun-synchronous” matching, solar is an economical choice over windmills and engine-driven generators for most locations where utility power is non-existent. Owners of solar water pumping systems enjoy a reliable power system that requires no fuel and very little attention.
Solar modules should be located in a sunny spot where no shading occurs. Even shadows from a tree limb, tall grass, or fence rails can substantially reduce power output.
For these reasons we typically mount the solar modules on a pole or ground mount above any obstacles. Remember the solar array can be placed some distance from the water source if shading is a problem. Wire size can be increased to compensate for longer cable runs and the associated voltage drop.
While batteries may seem like a good idea, they have a number of disadvantages in pumping systems. They reduce the efficiency of the overall system. The solar modules operating voltage is dictated by the battery bank and is reduced substantially from levels, which are achieved by operating the pump directly. Batteries also require additional maintenance and under and over-charge protection circuitry which adds to the cost and complexity of a given system. Water storage for off-season use is more cost effective in the longer term than having batteries for backup.
Solar farms or Utility-Scale Solar Energy Technologies (USSE PV), like the one shown here, are a large system of solar panels with a special type of inverter called the grid-tie inverter. Grid-tie inverters that feed power into a power supply network. This assembly of panels covers a large expanse of land, and harnesses huge amounts of solar energy. and are designed for large-scale solar energy generation that feeds directly into the grid, as opposed to individual solar panels that usually power a single home or building.
The sole purpose of the solar farm is to feed energy into an existing grid. Due to the enormous size of the power requirements, these farms are situated well away from residential homes. A very large area of land is required, though new ideas of floating solar farms exist now buoyed up on available bodies of water.
The solar farm consists of a large number of solar panels, a power conditioning unit (PCU) with a grid-tie inverter having an option of a BESS – Battery Energy Storage System to smoothen fluctuations in power generated by the solar plant. the power produced by the solar farm is often transmitted via medium voltage transformers and transmission lines several kilometers to end-users.
Solar energy mini-grids, powered by solar is a power generation system useful in areas far from the utility lines. A mini-grid is an integrated local electricity generation, transmission, and distribution system serving numerous customers. They are electrically isolated from the national grid and constitute an independent power generation plant.
They are a viable option for providing power to small economically viable communities with supporting commercial and agro-allied infrastructure. The solar component is combined with a backup diesel generator in most cases or a biogas plant and a containerized battery structure. These units provide reliable and high-quality power supply in these rural areas.
They promote the emergence of small-scale businesses in these areas fostering rapid economic growth and curbing the trend of rural-urban migration.
For mini-grids to be viable, certain factors have to be considered, namely:
- Existence of commercial or agro-allied economic activity e.g. community water pumping agricultural irrigation schemes, cottage industries or small/medium scale businesses
- Security concerns for installed equipment.
- Size or number of potential subscribers to the scheme
- Willingness to participate in financial support to bear costs of maintenance of the installed plant
- Location and spatial orientation/ distribution of the off-takers and businesses to be powered by the plant. This will determine the reticulation pattern and costs of the eventual power distribution network.
- Availability of preferably non-arable land adequate for placement of solar panels and critical infrastructure.
BIPV stands for Building Integrated PhotoVoltaics. This adaptation of solar power is a means of providing additional power for ancillary power requirements in large buildings within the city.
These systems utilize transparent solar panels used instead of the normal glass facades on high-rise buildings. these panels are mounted on frames on the exterior of the building and the energy harnessed by the panels is used to offset the energy requirements of the building like emergency lights, elevators, and area. The Frodeparken in Uppsala, Sweden is a wonderful example of technology applied to more advanced purposes. Not only is the building aesthetically pleasing, but it is also very functional, providing clean energy to 70 apartments and shops.
- reduction cooling and heating requirements of the building interior, as the BIPV unit acts as the temperature buffer preventing sharp temperature fluctuations
- power is provided in-situ without the need for more land area.
- More efficient use of daylight and reduction in carbon footprint due to reduced demand on utility supply.
- Less accumulation of dirt and grime as gravity acts against the buildup on the surface of the panels.
- Easily, mounting solar panels on a vast vertical wall proves the hardest challenge.
- Maintenance issues high up on the wall will require scaffoldings and cable systems to get workmen up along the wall. that often proves laborious and amounts to extra costs
- In areas closer to the equator there are fewer gains as the angles on incidence on vertical facades are lower, due to the height of the sun in the sky. the opposite is the case during the winter months at latitudes higher than the tropics
To focus on contributing to the sustainability of the earth’s resources via the use of environmentally friendly solutions from renewable energies as a decisive step towards countering climate change and ensuring a future worth living for our children and future generations.
To develop a reputation in the renewable energy industry as a trusted and reliable partner , fully committed to meeting of our customer’s energy requirements. With sound work ethic and morals to maintain our customer’s long-term trust and support.