Solar inverters are box-like components of a solar system that convert the electric input from the panel to a form used on electric equipment at our houses. There are several types of solar inverters, and one of them is the plug-and-play grid-tie solar inverter.
The plug-and-play inverters are lighter and connect to the solar panel directly through a standard socket. However, per the law, these inverters have been required to shut down during utility outages per the IEEE 1547. Consequently, there has been a lot of fuss over the internet about these devices, with everyone wondering if they are legal to use. To fully grasp the issue surrounding the plug-in grid inverters, we will first look at its upsides and then make it clear if it is legal or not.
How do plug-in solar inverters work?
Solar components such as inverters account for approximately 40% of the cost incurred when installing a roof-top system, as stated in the NREL study 2017. The main advantage of the plug-in and-play solar inverters is their straightforward installation process. Basically, after setting up the panel, you only need to plug the inverter and in to get everything working. Even better, the plugging does not require any expertise and can be done by anyone.
As a result, plug-in and pay companies have managed to lure most people into purchasing these devices due to their affordable cost, as indicated below.
We will compare installing a 5kw solar system with a micro inverter, requiring a professional and a plug-in inverter.
| Installation Type | System Size | $/Watt Cost | Total Cost |
| Hire an Installer | 5 kW | $3.13 | $15,650 |
| Plug and Play | 5 kW | $1.60 | $7,990 |
Moreover, with this inverter, you can isolate some of the components for maintenance and repair. How is that? The current flows from the panels to the inverter via a breaker. Consequently, when there is the production of bad voltage, the breaker cuts off the circuit, which prevents overheating and potential fire accidents.
Moreover, this type of inverter shuts down in case of anti-islanding. However, when the deal seems too good, it calls us to give it a second thought. Are these solar inverters as good as they proclaim to be?
Why you shouldn’t invest in a plug-in solar inverter
Several issues surrounding the plug-in inverters, which compromise their credibility. Consequently, these inverters have not been fully certified as of 2021.
One of the significant drawbacks hindering their certification is safety concerns. Before we jump right in, you should note that electrical systems are prone to fire accidents. Thus you should ensure that the manufacturer delivers safety mechanisms to prevent all your life investments from draining into waste.
Solar inverters are tested against AS 4777.2 and AS3100 to guarantee their safety. Unfortunately, the plug-in inverters require a dedicated circuit on the switchboard. Consequently, a lot of energy flows in and out of one circuit. As a result, the circuit can be damaged in case of a slight error, resulting in a fire. Besides, they will require several power cords to distribute the power, which can be pretty messy.
Above that, these systems are not installed by a licensed technician or signed off by your utility company. You are happy that you can do it all by yourself. We are sorry to disappoint you; that fact, among others, makes plug-in inverters illegal in some areas. How?
Fact that they are not signed by your utility company or installed by a professional, they feed electricity into a circuit without the required shutoff features. Consequently, they are likely to violate the local utility codes, making them illegal.
Apart from that, you can easily bump over plug-in inverters because of their size and may look quite clunky. Besides, troubleshooting these inverters can be a big issue. It has several dedicated circuits, which might take several hours to identify the point of failure. Again, in most cases, its troubleshooting process will always require you to hire a professional.
Final words
The plug-in inverters were invented in 2012, and since then, the plugged solar and unplug companies have been facing high demand for these devices. They are pretty easy to install which you can do it all by yourself. Besides, they are pretty small compared to the typical on-grid or off-grid inverters, making them quite portable, especially when moving to a new house.
Because you will plug the inverter directly into the power socket all by yourself, you will not require a licensed technician. Coupling with its safety concerns, these inverters are not licensed by a power utility company. Apart from that, they need dedicated circuits which violate the codes of most local power utilities. As a result, plug-in inverters are illegal in some areas.
Eng. Matthew Joseph Nandirio is the Founder of walkingsolar.
After graduating from the University of Houston in 2002, matt started working as a Solar Electrical Engineer for several multi-national solar energy companies.
He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research.
He now shares his 20 years of expertise through his articles on the walkingsolar website.
Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.