We know that solar panels produce Direct Current electricity. This needs to be converted to AC (Alternating Current) in order to power the appliances connected to the solar PV system. This is where the inverters come in. The types are:
- Central and String Inverters: Individual solar panels are connected in series to form strings in order to get a higher voltage rating. DC power from these strings is then taken to central or string inverters for conversion. Central and String Inverters have been around for a long time. Connections from all solar panels are taken to one inverter of high rating in case of a central inverter. In string inverter system, there are multiple smaller inverters for several strings.
- Micro Inverters: These are relatively new entrants to the market.
Now what exactly are micro inverters?
Micro inverters are small inverters (both size-wise and rating-wise) that are designed to be attached to the back of each solar panel of the array. In some cases, they are attached to two solar panels instead of just one. With these, the direct current produced from the respective panels is inverted to alternating current and is then sent into the appliances.
What are the advantages micro inverters provide in comparison to the traditional inverters?
Micro inverters, being a nascent and advanced technology, score over the conventional inverters in quite a few aspects. A few important ones are listed below.
- Individual optimisation:
The biggest advantage of using these inverters is that even if one panel becomes shaded or fails due to some other reason, it won’t affect the rest of the array. In a set up where solar panels are attached in series, the panels act like one unit. Here, if one panel under-performs, the whole array will be affected. Micro inverters eliminate this problem because every solar panel is independent and if the there is any defect or problem with one of them, the rest of the panels pump out power normally. With micro inverters, there is no single point of failure.
Central or string inverters come in limited power ratings. Solar arrays on the other hand, come in various sizes, depending on our energy needs. Because the size of these inverters is limited, we might end up having to pay for a bigger one than what exactly matches our needs. Micro inverters, on the other hand, can be customised to the exact number of panels we have.
Since they have to handle low power, they are designed to be more reliable than the traditional inverters. Due to this, manufacturers are able to quote a longer warranty period for these, a period of 15-25 years as against 5-10 years for the traditional inverters.
- Improved Safety:
Solar panels, when connected in series, together produce DC voltage of high rating. This power needs to be conveyed to the central or string inverters. Handling DC current of a high rating are potentially life-threatening .Micro inverters eliminate the need for high voltage DC wiring which improves the safety factory, both for the owners and the installers.
As we see above, there are considerable advantages for the micro inverters. However they come with quite a few disadvantages as well. Some are:
- Micro inverters are associated with more upfront investments. It comes with higher installation costs. It also involves higher costs for servicing and maintenance.
- Micro inverters are exposed to harsh weather conditions like high heat. Central and string inverters are usually housed in protective environments.
- Voltage drops in long runs of AC power as needed by micro inverters are more significant than those associated with DC transmission required by central and string inverters
So, as we see, micro inverter is a winner in many levels. If you are looking for the highest quality, safest and the best performing inverters, going for these make sense. Micro-Inverters are yet to go really popular because of the cost it comes at. The economics of micro-inverters are currently being looked into and it is believed that soon micro-inverters will take over from the others in terms of usage.
- What is a String Inverter?
- What Type of Inverter Should I Choose for Rooftop Solar? Central, String or Micro Inverters?
- What is the Lifetime of Solar Inverters?
- What are the Different Types of Inverters Used in Solar PV Power Plants?
- What are the Typical Guarantees and Warranties That Come with the Solar Power System?