SolarEdge Inverter: What is a Solar Inverter and Why You Need One?

For many homeowners, a solar photovoltaic (PV) system is a simple way to reduce your household carbon footprint while making the switch to a renewable, non-polluting energy source. Whether you choose to go completely off-grid with a solar PV system or stay connected to the grid, a high-quality solar inverter is an essential piece of equipment that your home PV system will need. Most people, however, spend most of their time researching the best type of solar panel for their renewable energy system. 

While solar panels are an essential part of any residential PV system, the inverter is often overlooked, with homeowners opting for an inexpensive inverter that is simple to install. However, choosing a suitable inverter can go a long way in significantly increasing your solar PV system's overall efficiency and energy output. Below, we explain the essential functions of an inverter, the different types of inverters on the market today, and end by offering a complete, unbiased review of the SolarEdge inverter. 

What Is an Inverter, and Why Do You Need One?

The solar panels on your roof are manufactured to create an electrical charge by creating silicone layers infused with materials like boron and phosphorous. When photons from sunlight then hit these electrically charged PV cells, electrons are freed and generate a source of energy. However, the energy created by these loosened photons is known as direct current, or DC, electricity. While DC electricity is commonly used in recreational vehicles (RVs) and houseboats, almost all homes are wired for alternating current, AC, electricity. An inverter, then, is a necessary piece of equipment that will convert the energy produced by your solar panels into a usable source of electricity for your home. 

Today, there are essentially three different types of inverters used in residential and commercial PV systems. 

1. Centralized Inverters. These inverters are the most inexpensive option and were the most common in the early days of solar energy generation. A centralized inverter connects all solar panels to a centralized electrical panel, also known as a string inverter. While this makes for an easy installation, it is also widely considered the most inefficient inverter. Why? Because if just one individual solar panel is shaded by a tree or covered in snow, it will reduce the electricity output for the entire system. 
2. Micro-inverters. These inverters are essentially miniature versions of the centralized inverter installed on each solar panel. Micro-inverters solved the problem with centralized inverters: if half of your roof receives afternoon shading, the reduced energy production from those individual panels will not negatively disturb the production capacities of the rest of the panels. 
3. Power Optimizers. Power optimizers are a type of hybrid option considered the most efficient (though also most costly) option on the market. These mini inverters are installed on each panel but do not directly change the current to AC electricity. Instead, power optimizers enhance the DC (thus creating a more efficient solar energy production) before sending that energy to a centralized inverter. 

The best inverter for your residential PV system will not only help you to optimize the solar power production from your solar panels, but most inverters also offer data monitoring services so that you can determine how much energy your system is producing and devise strategies to increase the overall output. 

What to look for in a quality inverter for your residential solar PV system

Besides deciding between the different types of inverters on the market, three other considerations are for choosing the best inverter for your residential solar PV system. 

• Continuous Watts. Continuous watts are the measurement of the total amount of watts that an inverter can support. Essentially, you will want your inverter to be sized equal to the watt rating of your solar system. For example, a 3,000-watt (or 3 kW) solar PV system would need an inverter that can take 3,000 continuous watts. If you purchase an inverter with a higher rating than your PV system, the overall energy efficiency from your PV system will drop. 
• Surge Watts. Many household appliances use an extra amount of energy when the motor is being turned on. For example, refrigerators with an 800-watt rating might need an additional 1,200 watts of surge power when initially turned on as the compressor kicks in. The surge watt rating for your inverter measures the amount of energy the inverter can support for a limited amount of time. In most cases, the surge watt rating is between 1.5 and 2 times the continuous watt rating. If you regularly use heavy machinery with a high surge watt requirement, you will need to check the surge watt rating of specific appliances and size your inverter accordingly. 
• Monitoring Devices. The best inverters on the market today also include monitoring technology that will help you learn how much electricity your system generates at any given period—right from your home computer, tablet, or smartphone. As with most elements of a sustainable home, proper management of your solar PV system is the best way to get the most out of your investment. With monitoring devices, for example, you might be able to discover that through periodic pruning of trees on your property, you could potentially increase the overall renewable energy output of your solar PV system. Without any monitoring, you are essentially trusting that it works—which is not always the case.

The SolarEdge Inverter

While several different companies offer high-quality inverters for residential solar PV arrays, SolarEdge Inverter Technologies Inc. offers both single-phase and three-phase inverters that can help homeowners increase the overall energy output of their solar panels. 

The "intelligent inverter systems" that this company manufactures rely on power optimizers that maximize the power generation for every panel in your home PV system. Essentially, the SolarEdge inverters connected to each panel on your rooftop supply the optimum voltage to maximize power generation for each panel. The mini inverters connected to each panel in your system don't change the current to AC (thus reducing energy loss), but rather are DC to DC converters that first optimize the string voltage before delivering that DC energy to the centralized inverter at the end of the system. 

Suppose one panel in your system is shaded or simply not performing up to the standard of the rest of the system. In that case, the SolarEdge inverter technology can bypass that panel and still provide the optimum voltage to the centralized inverter. 

The new, three-phase inverters developed by SolarEdge include a digital control technology with the power conversion technology mentioned above to maximize the efficiency rating of your system. The fixed-voltage technology ensures that your solar inverter is set for optimal input voltage despite environmental conditions like periodic rooftop shading. 

A data-monitoring receiver is integrated into the inverter and allows you (or your installation company) to monitor the performance data from each PV module in your system. A web-based SolarEdge monitoring platform makes it easy to check your system's overall performance while troubleshooting system faults. The company also provides an app called SetApp, which allows you to monitor your system from your smartphone. 

The SolarEdge three-phase inverter is offered in the following sizes: 3kW, 4kW, 5kW, 7kW, 8kW, 9kW, and 10kW, and comes with a 12-year warranty. In most cases, the extra installation cost that might come with SolarEdge inverter technology is offset through the increased energy production over the lifetime of your solar PV system. 

On the downside, SolarEdge inverters might not be a good option for smaller solar PV systems that deal with excessive shading. This will drop the inverters out of the required voltage range for the inverter technology. This can also be a problem for rooftop PV systems that face different orientations. For example, if you have rooftop solar panels that face south and west, the excessive morning shade on the west-facing panels can strain the south-facing panels and result in low performance during morning hours. Suppose either of the two situations reflects your situation. In that case, you might want to search for SolarEdge inverters with a higher voltage range, such as the P505 optimizer, which has a higher maximum input voltage. 

Bottom line

As long as you invest in solar panels, it's worth checking out the inverters that make solar electricity work for your home. SolarEdge is a company that is based out of Israel; you can find a list of US-based companies that market their inverter products here.

Article by:

Tobias Roberts

Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.