In this article I will explain how photovoltaic solar energy works .
A photovoltaic (PV) or solar power installation converts sunlight into electricity. In such an installation, the solar panels collect solar energy in the form of direct current.
An inverter then converts that direct current into alternating current so that you can use the energy in the house. The surplus of electricity is delivered to the electricity grid.
1. Solar
panels Solar panels or photovoltaic panels consist of different solar cells. When sunlight falls on such a solar cell, the electrons in the cell start to move and direct current is created.
2. Inverter
The inverter is the heart of any PV system. This device converts the direct current from the solar panels into alternating current. During this conversion it is very important that as little energy as possible is lost. The efficiency of an inverter is therefore essential.
3. Meters
BelgiumThe Netherlands
green electricity counter
The green energy counter records how many kWh your installation produces. This is important for the amount of green energy certificates you receive.
Electricity meter
The electricity meter registers what you take from the grid yourself and therefore runs backwards when you produce more than you consume.
Electricity meter
The electricity meter registers what you take from the grid yourself and therefore runs backwards when you produce more than you consume.
4. Monitoring
system A monitoring system makes it possible to remotely view and possibly save the production of your inverter. You can also be kept informed in the event of a malfunction.
The tasks of an inverter
The tasks of an inverter are as varied as they are demanding:
1. Low Loss DC to AC Conversion
One of the most important characteristics of an inverter is its conversion efficiency. This value indicates what part of the energy input as direct current is returned in the form of alternating current. Modern appliances operate with an efficiency of up to about 98 percent.
2. MPP tracking
The power curve of a solar panel is strongly dependent on the radiation intensity and the temperature of the solar panel, in other words on values that constantly change during the day. Therefore, the inverter must find the optimal operating point and permanently monitor it on the current curve. In this way, he gets the maximum power from the PV panels in every situation.
The optimum operating point is called the 'Maximum Power Point' (MPP). The search for and tracking of the MPP is therefore called “MPP tracking”. MPP tracking is very important for the energy output of a solar energy installation.
3. Monitoring and protection
On the one hand, the inverter monitors the energy yield of the solar energy installation and signals any problems. On the other hand, it monitors the electricity grid to which the inverter is connected. In the event of a problem in the grid, the inverter must therefore immediately disconnect the installation from the grid, for safety reasons or to support the grid - depending on the requirements of the local grid operator.
In addition, in most cases the inverter has a device that can safely interrupt the power of the panels. When the light shines, PV panels are always live and therefore cannot be switched off. If the inverter is disconnected during operation, it can cause dangerous arcs that will not be extinguished by the DC current. If the trip device is integrated directly into the inverter, installation and wiring can be performed much easier.
4. Communication
Communication interfaces on the drive make it possible to control and monitor all parameters, operating data and yields. The data can be queried and parameters set for the inverter via a network connection, industrial fieldbus such as RS485, or wirelessly via SMA Bluetooth®.
In most cases, the data is retrieved via a data logger, which collects, processes and - if desired - forwards the data from various inverters to a free online data portal (e.g. SMA Sunny Portal in combination with a Sunny WebBox, Sunny Home Manager or Webconnect ).
5. Temperature management
Temperature inside the inverter enclosure also affects efficiency. If the temperature rises too much, the inverter must reduce its power. Therefore, under certain circumstances, the available power of the panel cannot be fully utilized.
On the one hand, the installation location can influence the temperature, because a constantly cool environment is ideal. On the other hand, the temperature is directly dependent on the operation of the inverter: even an efficiency of 98 percent means a power loss of two percent (in the form of heat). If the installation power is 10 kW, then the maximum thermal capacity is still 200 watts.
That is why an efficient and reliable housing cooling system is very important, eg SMA's "OptiCool" cooling concept. The optimal thermal layout of the components allows them to release their heat directly to the environment, while the entire housing acts as a heat sink at the same time. This allows the inverters to operate at maximum rated capacity, even at ambient temperatures of up to 50°C.
6. Protection
With a weatherproof housing, ideally built in accordance with the protection class IP65, the inverter can be installed anywhere outdoors. This has the advantage that the inverter can be installed closer to the panels, which reduces the costs for the relatively expensive DC wiring.
