Solar inverter applications

A typical solar power system consists of a solar photovoltaic panel array and an inverter. Photovoltaic panels convert solar light directly into electrical energy in the form of a direct voltage; the inverter converts the DC voltage generated by the photovoltaic panel into an AC voltage that can be sent to the grid. Therefore, the inverter has become the core component of the grid-connected photovoltaic system.

In addition to features such as high efficiency DC/AC conversion and maximum power point tracking (MPPT), the inverter should also meet the required quality - low total harmonic distortion (THD) current, high power factor ( Close to 1) and low EMI levels, provide AC power and optimize the energy transfer from the PV array to the grid as much as possible. In addition, the inverter must also meet the safety requirements of users, equipment and the power grid itself.

There are several topologies that inverters can use. One of them is the use of an H-bridge driven linear transformer. This is the simplest and most reliable way to provide complete isolation between the grid and the DC front end. It also circumvents this kind of situation that should be avoided when DC current enters the grid. However, the severe power loss of linear transformers leads to low efficiency, which is the drawback of this topology; the large size and weight of linear transformers are also defects of this topology.

Replacing a bulky linear transformer with an output inductor is another topology. This method has the highest efficiency in all topologies; this inverter is much lighter and more cost-effective than the inverter with a linear transformer because of the small size of the output inductor. However, its disadvantage is that it does not provide any form of electrical isolation between the grid and the photovoltaic panels.

Rural Electrified Off-grid Systems: Where electricity is not available, the PV system is connected to the battery via a charge controller. An inverter can be used to provide AC power for use by general appliances. A typical off-grid application is to power remote areas (such as mountainous houses and developing countries). Rural electrification refers to the following two types of applications: small-scale home solar systems that can meet the basic electricity needs of a household; or small-scale solar grids that can provide enough electricity for a few households.

There is also great potential for mobile phone relay station applications powered by photovoltaic or hybrid systems. Other applications include: traffic lights, HNA support systems, security phones, remote lighting, highway signs, and wastewater treatment plants. Because they can power areas where power is not transmitted, thus avoiding the high cost of laying wire mesh, these applications currently have cost advantages.

The MPPT system inside the inverter ensures that the inverter will always operate at the maximum power that the PV panel can output under all kinds of weather conditions and at any time during the day.