Important To Know Before Solar Power Designing

Important parameters for solar power systems designing.

In previous articles, we discussed the factors that significantly affect the solar power plant's efficiency. In this article, we will go through important parameters that should be known well before designing or calculating the solar power system. The performance parameters for all the used equipment must be taken into consideration to have a super-efficient solar power system.

What are the Solar power system components?
The common standard equipment used in the solar power system is listed below. Note that we will list all the devices used which may be considered optional but when used will be added value for the system. These devices’ cost impact should be studied. The components are:

Solar panels (PV panels).

MPPT and charge controller devices.

Tracking system.

Dust cleaning system.

Batteries.

Inverter.

Solar panel concerns:

As we know, the solar Panel is the main equipment that converts solar energy to electrical power. Without Solar panels or a problem or damage, there will not be electrical power there. When designing a solar power system, some important parameters should be considered during the design and engineering phase these parameters are:

The calculation of the sizing of Solar panels should consider the power losses and device efficiencies.

Solar panel efficiency. The more efficiency, the more power generated from the solar cells. The solar panel's efficiency written in the datasheet of the panel is the specs in special conditions called standard test conditions (STC). The actual efficiency is lower than the written one.

Solar panel Temperature effect. It is very important as when temperature increases because of global warming and climate change, the panel power decreases and the efficiency decreases. During installation keep a way around the solar panels to allow air to circulate. That will enable some cooling for panels.

The selection of the System voltage should be matched with the operating voltage mentioned in the manual and datasheet of the solar panels or you have to modify the connection arrangement (series or parallel) of the panel to match the system voltage.

The selection of the solar power plant (rooftop or solar power farm) should consider the shading from surrounding buildings or trees to be away.

Tracking system.

The Irradiance or insolation and the behavior of the solar power system or project should be studied well to determine the orientation of the solar panel at the area of the project. There are three options for tracking the sunlight, the first option is not to use any tracking system by fixing the panels at a certain angle of the solar panels (it may be the same latitude angle for the installation place) it may be from 30 to 45 degrees and keep it all the time. Some of them recommend changing this angle in winter to a certain angle and another angle in summer by adding or subtracting 15 degrees.

The second option recommends a technique that uses an electromechanical tracking system where the panels follow a fixed track during daylight after studying the behavior of the sunlight at the place. the best option is to use the electromechanical tracking system with the pyrheliometer sensor to measure the direct beam of solar radiation and connect it with a controller to be used with this electrotechnical tracker. However, that option is not used widely because it is very expensive and used only through research.

Dust cleaning system.

The amount of dust accumulated on the surface affects the solar radiation reaching the solar cells and as a result, decreases the electrical generated power. So, there is a need to clean the solar panels. An automatic cleaning system could be added to the system to clean the panels’ surfaces periodically to keep the maximum solar radiation. The other way is not to install the automatic system but the panels should be cleaned manually.

Batteries.

There are no fixed rules for choosing the battery where the battery size should be calculated. The calculation is based on the following:

Total load calculation should include the power losses and device efficiencies.

Battery depth of discharging where the maximum discharging percentage of the battery should be known to be considered in the battery sizing. We should know that the depth of discharging affects the life cycle of the batteries

The operation temperature affects also the efficiency of the battery and must be considered during the sizing of the battery. The lowering the temperature during cold days, the lowering the percentage of the available capacity.

Weather conditions of the installation place should be considered. For example, if there is repeated no sunlight for 2 days, that should be considered.

The manual of the batteries should be studied carefully and apply all the recommendations of the user manual.

Charger controller.

The selection of the charger controller depends on the total short circuit current of the solar panels. But we should add a safety factor for the starting current if the loads contain a high starting current. When the calculation of the charger controller determines the Amps of the charger controller, the higher value should be chosen if there is no same value in the market.

For example, some charger controllers indicated in their manual the charging current is 5, 10, 20, or 30 amps so, the nearest higher one should be chosen. Some manuals also for charge controllers recommend the number of cells per panel like using 36 cell solar panel for 12 volts and 72 cell solar panel for 24 volts.

Inverter.

The size selection of the inverter should be more than the load power by approximately 30% as a safety margin in case of future load increasing and the starting current mentioned in the data sheet of each load device

The efficiency of the inverter should be considered during the sizing of the inverter.

The size and the power of the solar panels should be considered to meet the power and amps of the inverter. This also be noticed in the solar panel sizing.