More than 14 million Enphase microinverters have been installed worldwide. According to Martyn Berry, European Director of Technical Services at Enphase Energy, this success is partly due to the fact that the company sets the bar incredibly high when it comes to safety. ‘Our technology is among the safest in the solar industry, for the owner of solar panels and for the installer as well, but also for the fire department if action is required due to a fire in a building with solar panels on the roof.’
Ensuring the safety of a solar energy system starts with the use of high-quality critical components. That means that the choice for Enphase microinverters is obvious, according to Berry. This is primarily due to the fact that safety issues of solar panels are usually related to high voltages of direct current (DC) that can build up in systems with old-fashioned inverters. That risk has been eliminated in Enphase’s energy architecture.
‘But when we talk about solar panels and safety, we have to start with the enormous growth of the market,’ says Berry. ‘Wherever the rollout of solar energy accelerates, money can be made. This attracts many new parties, including installers. Not all of them have the competencies that you would like to see when installing solar panels. After all, working with alternating current (AC) is not the same as working with direct current (DC). It involves very different and bigger risks. From that point of view, the growing attention to quality and safety – for example by training and certifying installers and inspecting solar energy systems before they go online – is of great value.’
Enphase microinverters are the result of more than 15 years of innovation. The company has recently launched the eighth generation of its technology in America. These inverters are also characterized by a mix of safety and intelligent performance. They distinguish themselves, among other things, in terms of easy installation and optimizing the efficiency of solar panels. In addition, the inverters are built to last the full life of a solar energy system. They are robust and have no degradation, partly because they are completely encapsulated in silicone, which of course also ensures long-term safety. But where exactly does that safety lie?
Berry: ‘Enphase microinverters are connected directly to the output of each solar panel. They immediately convert the DC that is generated in that solar panel into a low voltage AC. Old-fashioned string inverters work differently. DC cables run from each solar panel to the inverter which then converts the direct current into alternating current. As a result, the DC voltage in a circuit can increase enormously, up to 600 volts on the roofs of homes and 1.000 volts in commercial systems. That brings danger. If you use Enphase’s inverter technology, it stays below 60 volts DC. This offers various advantages in terms of safety, both for the installer and the end user.’
If an electric charge is passed between two electrodes, an electric arc can occur. This is also possible in solar panel installations, for example in case of short circuit, damage to cables or bad connections. If the current continues to flow, it will continue to feed an electric arc. The possible consequences are damage, or in the worst-case scenario fire.
‘Enphase inverter technology almost completely eliminates this risk’, says Berry. ‘We do not bring high voltages DC into a house or other building. The low voltage AC ensures that no electric arc can occur. In addition, within our architecture you only work with one cable in a series connection. Compared to string inverters, there is much less need for cutting, extending, insulating or bundling... This also reduces the risk of damage or fire occurring. Moreover, this means working with Enphase microinverters is a lot safer for the installer. After all, during installation, the current in a solar energy system already builds up, even if it is not yet connected. No one wants to get a huge shock with DC, also because unlike AC you tend to hold on. In addition to direct injury, when working at height, there is a chance that this will lead to a nasty fall.’
More and more standards and fire safety regulations call for a rapid shut down (RSD) function for a solar energy system. It is already mandatory by law in America and the European Union is going to vote on capturing this in regulation. Many insurers recommend the use of microinverters due to the presence of an RSD function. The primary reason is to improve the safety of firefighters while extinguishing a fire in a home or building with solar panels on the roof. Berry thinks the growing attention for this theme is justified. The more the rollout of solar panels progresses, the more often they are part of fires in buildings. Bringing the solar energy system to a safe state is of great importance in such a situation.
Berry: ‘It must be possible to reduce the current to zero in a short period of time to guarantee the safety of the firemen and rescue workers. The fire brigade wants to control that and have the certainty that it works. This is problematic with string inverters. As long as the sun is shining, the DC continues to flow, even when the inverters are switched off. If you come into contact with such a cable, this can result in a significant shock or even electrocution. With our technology, it’s a different story. We work with AC and the voltage in the cable circuit is already significantly lower. In the event of a failure in the electricity grid, or if you hit the off switch, our microinverters stop producing power. There is no power left in the system within 30 seconds. Interesting in this context is the home battery which is quickly becoming mainstream in many places. This involves similar issues with regard to fire safety, safe installation and the control of calamities. We supply our own Enphase battery. That is a lithium iron phosphate DC battery in which we also use microinverters. So we are also raising the bar in terms of safety with regard to this development
in sustainable technology.’