Info about PV and how it works

About PV power systems

PV systems convert sunlight directly into electricity.
PV power systems enable home owners , institutions, or companies to generate some or all of their daily electrical energy demand on their own roof, and store the excess daytime power into batteries for later use when needed, e.g during the night.

1. Off grid power systems

Off-grid power systems are PV systems which power houses or institutions and are not in anyway connected to the public electric network.

They are applicable in places without public power grid e.g. isolated areas, rural areas where there is no electricity network and infrastructure  and in cities where its expensive to tap electricity from the public electric network and also the electricity from the public electric network is expensive.

System components:

  • Solar PV modules
  • Mounting racks
  • Inverter
  • Charge controller
  • Batteries
  • Surge protector
  • Breakers

 

2. Photovoltaic system connected to the grid (on grid)

PV systems that power the whole housing during the day and night and only use public electric network as back up. This is applicable to where the public electric network is close and electricity can be tapped from it but their monthly charges are expensive.
Components: Solar PV modules, mounting racks, inverter, charge controller, batteries, surge protector, breaker, etc.

PV systems that power the whole house during the day and public electric network takes over during the night, this is mostly suited for industries.
Components: Solar PV modules, mountain racks, inverter, breaker, surge protector, etc

PV systems that supplies power as a back up to the public electric network, this is suitable for places where the public electric network is available but its prone to blackouts and disconnection. When the public electric network goes off, solar kicks in for the time until its back.

Components: PV modules, mounting racks, inverter, charge controller, batteries, battery disconnect, change over switch, sage protector, breaker.

Reduce electricity bill — Since you will be using electricity your solar system has generated, your energy bill will drop, how much you save will depend on the size of the solar system .

Highly reliable — The estimated lifetime of a sauna PV model is 30 years. Furthermore, the module performance is very high providing over 80% of the initial power after 25 years making it reliable in the long term.

Free energy — The sun is the only resource needed to power solar panels.

Little maintenance required — Solar PV sector requires minimum maintenance. You just need to keep the system generally clean. As there are no moving parts, wear and tear is minimal. The inverter is the only part that requires change after 10 to 15 years because it is continuously working to convert solar to electricity. After covering the initial cost of the solar system, you can expect very little spending on maintenance and repair work.

Long lifespan – Between 25 to 30 years.

Produces no noise, no harmful emissions, or pollutant gases.

Solar power systems bring electricity to remote areas.

SOLAR MODULES

The heart of the photovoltaic (PV) system is the solar module. Many PV cells are wired together by the manufacturer to produce a solar module. When installed at site , solar modules are wired together in series to form a string. Strings of modules are connected in parallel to form an array.

MOUNTING OPTIONS

Often the most convenient and appropriate place to put the PV array is on the roof of the building. The PV array may be mounted above and parallel to the roof surface with a standoff of several inches for cooling purposes. Sometimes, such as with flat roofs, a separate structure with a more optimal tilt angle is mounted on the roof.

Proper roof mounting can be labor intensive. Particular attention must be paid to the roof structure and the weather sealing of roof penetrations. It is possible to have one support bracket for every 100 watts of PV modules. For new construction, support brackets are usually mounted after the roof decking is applied and before the roofing material is installed. The crew in charge of laying out the array mounting system normally installs the brackets. The roofing contractor can then flash around the brackets as they install the roof. A simple installation detail and a sample of the support bracket is often all that is needed for a roofing contractor to estimate the flashing cost.

Masonry roofs are often structurally designed near the limit of their weight bearing capacity. In this case, the roof structure must either be enhanced to handle the additional weight of the PV system or the masonry roof transitioned to composition shingles in the area where the PV array is to be mounted. By transitioning to a lighter roofing product, there is no need to reinforce the roof structure since the combined weight of composite singles and PV array is usually less than the displaced masonry product.

Shade structure

An alternative to roof mounting is to mount the system as a shade structure. A shade structure may be patio cover or deck shade trellis where the PV array becomes the shade. These shade structures can support small to large PV systems.

Array mounting racks
Arrays are most commonly mounted on roofs or steel poles set in concrete. In certain applications, they may be mounted at ground level or on building walls. Solar modules can also be mounted to serve as part, or all of a shade structure such as patio cover. On roof mounted systems, the PV array is typically mounted on fixed racks, parallel to the roof for aesthetic reasons and stood off several inches above the roof surface to allow airflow that will keep them as cool as practical.

SURGE PROTECTION

Surge protectors help to protect your system from power surge that may occur if the PV system or nearby power lines are struck by lightning. A power surge is an increase in voltage, significantly above the design voltage.

INVERTERS

Inverters take care of four basic tasks of power conditioning

  • Converting DC power coming from the PV modules or battery bank bank to AC.
  • Ensuring that the frequency of the AC cycles is 60 cycles per second.
  • Reducing the voltage fluctuations.
  • Ensuring that the shape of the AC wave is appropriate for the application, i.e pure sine wave for grid-connected systems.

Most grid-connected inverters can be installed outdoors, while most off-grid inverters are not weather proof. There are essentially 2 types of grid-interactive inverters: those designed for use with batteries and those designed for a system without batteries.

CHARGE CONTROLLER

A charge controller , sometimes referred to as a photovoltaic controller or battery charger, is only necessary in systems with battery back up. The primary function of a charge controller is to prevent overcharging of the batteries. Most also include a low-voltage disconnect that prevents over-discharging batteries. In addition, charge controllers prevent charge from draining back to solar modules at night.Some modern charge controllers incorporate maximum power point tracking, which optimises the PV array’s output, increasing the energy it produces.

BATTERY BANK

Batteries store direct current (DC) electrical energy for later use.

PV cells convert sunlight to direct current [DC] electricity and is stored in batteries.

Charge controllers control the power from the solar panels which, if goes back to the panels from the storage, would damage the panels. It therefore ensures that all power stays in the panels and also relays the amount of energy stored in your batteries.

Battery system act as storage of electric power which will be used when needed e.g. at night. From the battery the system is connected to the inverters which convert direct current [DC] into alternative current [AC]. All appliances use AC.

  • Salar modules- Our modules are very durable, long lasting and can withstand severe weather including extreme heat, cold and hailstorms and have 25 years and above warranty.
  • Inverter -inverters carry a warranty of more than 3 years.

It is recommended that preventive inspection and maintenance works are carried out every 6-12 months. The PV modules require routine visual inspection for signs of damage, dirt build up or shade encroachment. Solar PV system fixtures must be checked for corrosion. This is to ensure that the solar PV system is safely secured.

While the inverters functionality can be remotely verified, only on-site inspection can verify the state of lightning surge arrestors, cable connections, and circuit breakers.
The following table shows some recommendations on the preventive maintenance works on the components and equipment, and the corresponding remedial actions to be carried out by qualified personnel.

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