The micro inverters you didn’t know you needed

Posted on 20 Mar, 2017 in Energy Storage, Solar Power

What are the ins and outs of micro inverters?

Inverters are the unsung heroes of the solar panel industry. They provide an answer to the question: "How do I turn solar power into useable electricity for my home?"

Solar energy is produced in direct current (DC), yet houses use alternating current (AC). It's as if the two are speaking different languages. Inverters play the vital role as translators, converting DC current to AC, which is then fed into our homes or the grid.

However, not all inverters are created equal. Traditionally, 'string' series inverters have been the norm, but have more recently given way to 'micro' inverters. They both play the translator role, but also contribute to the overall efficiency of your solar panel system in different ways.

Inverters play a vital role in solar power.
Inverters play a vital role in solar power.

What's the difference between micro and string inverters?

The difference between micro and string inverters comes down to where they're placed within a solar power system. Kunal Kapoor, electrical engineer at RK Solar and Consulting Services explains:

"Essentially, a normal string inverter works by connecting each panel to the next in a 'string', with the current passing through a single inverter to convert power from DC to AC. However, with micro inverters, instead of the DC power going from the roof down to the meter box, there's a small inverter connected behind each panel converting the current to AC directly."

With micro inverters, the 'translation' happens right away, whereas with string inverters, the system waits until all the power is collected before translation begins. This is a subtle, but crucial difference when it comes to the overall efficiency of the system.

Are micro inverters better than string inverters?

The biggest drawback of string inverters, according to Kunal, is that a drop in efficiency of a single unit (such as a shaded or faulty panel), lowers the output of the whole string. Micro inverters circumvent this, and are designed to function in sub-optimal conditions, allowing for variations without affecting the outcome of the system. 

"In the string inverter system, if a panel or a part of the string is shaded, the efficiency of the full string gets affected. Basically, the inverter accepts the lowest power output of all the panels and then brings the string down to that level before converting it," says Kunal.

Even in perfect conditions, micro inverters outdo string inverters by 9 to 25 per cent.

For example, each panel has a power tolerance (generally ranging between 0 to 5 per cent). With this tolerance in mind, some panels could produce 105 Ws and some could produce 100 Ws. In a string inverter system, even if the majority of panels are functioning at 105 W, the inverter brings down the output of the system to the lowest performing panel. The end result is a drop in output.

With micro inverters,  there is an inverter behind every panel – each one works independently from the other to give the best overall performance of the system. A panel is giving 105 W? Its output is 105 W, regardless of what its neighbouring panels are doing. 

Micro inverters provide a solution for clients where there's unavoidable variation in environmental conditions – such as partial shading, cloudy skies or when panels are spread over multiple roof faces – causing difference in performance between panels. Yet, even in perfect conditions, micro inverters outdo string inverters by 9 to 25 per cent, according to Kunal.

"Sometimes when people have smaller roofs and they want to put panels on three different sections, you can do this with micro inverters because each individual panel is performing to the best possible output they have. In a string inverter system this isn't possible."

Micro inverters are perfect for panels on different roof faces.
Micro inverters are perfect for panels on different roof faces.

Enphase micro inverters

Many people install solar panels because they want a level of control over how they use and spend energy. Because micro inverters are linked to individual panels, users can monitor how their system function in a way series inverters cant. 

RK Solar and Consulting Services Enphase micro inverter gives peace of mind for users who want to track their energy consumption and how their panels are performing. Through the online tools, users are able to monitor their system in real time and how much energy they're producing and consuming via smartphone, tablet or computer.

Knowing what your system is doing at any given time is a fantastic tool for getting the most out of solar power, says Kunal. By pinpointing when you're likely to consume the most power, or when your system is producing the most energy, you're about to optimise your energy consumption on a daily basis. lets 

Linking micro inverters and solar batteries

Batteries are the future of solar power, giving homeowners a way to store the energy produced by the sun they're not using for a later date. Micro inverters are 'battery-ready' from day one, so users who have an existing Enphase system can retrofit batteries when it suits them, without needing to install additional equipment. 

To find out more about RKS Solar and Consulting's solar panel solutions, or to find out how to get more detailed information out of your Enphase micro inverter system, get in touch with our friendly team today.

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