There is no doubt that one of the most exciting companies in the microinverter industry is Enphase Energy.
The focus of this company has always been to offer an interesting and different alternative to the typical central or string inverter solution most solar systems have.
Enphase revolutionised the solar industry with its microinverter alternative, a feature that has allowed it to deploy more than 17 million microinverters across 110 countries with nearly 12 thousand systems installed in Australia alone.
Why Should I Choose An Enphase Solution?
Here are a few reasons to go Enphase:
1. Increased Reliability
The system allows each module to act independently from the other, therefore, any failure in one of the microinverters or modules will not affect the others.
2. Reduction In Mismatch Losses
Attributed to disparities in the maximum power point of solar modules due to shading or manufacturing differences between modules.
The expansion is easy and cheap, as you only need to add as many microinverters as the number of modules you intend to add to your existing solar system.
Conventional configurations could require a change of central inverter which could drastically increase the cost of the expansion, making it unviable.
Working with high DC voltages is dangerous and the higher the number of modules in a string, the more dangerous it is.
Enphase microinverters reduce the risk of fire by not allowing the voltage to rise and create an arc flash in the case of a damaged wire.
5. Rapid Shutdown Compliance
This requirement involves the addition of a special combiner box and communication system (like Midnite’s Bird House) which also increases costs.
With Enphase microinverters you can save the cost of the special combiner box as it will automatically stop producing AC power if a grid failure is detected.
6. Energy Management
The Enphase Models
Across the 10 years of microinverter technology development, several models have been released into the market, each one of them for different applications.
Take, for instance, the basic M-series models in their two versions the M250 and the M215. Both of them are designed mainly for the residential sector and are compatible with 72 and 60 cell modules, with rated continuous AC output power of 240 W and 215 W respectively.
Other unique models such as the C-250 and the D-380, are designed mainly for the commercial sector.
The first one is coupled with an autotransformer of 480Y/277 V for three-phase applications, is compatible with 60 and 72 cell modules and can reach up to 350 W in AC power.
The second one, designed to include two microinverters inside it, is coupled with two PV modules.
Moreover, Enphase also released the IQ 6 and IQ 7 system - complete interactive systems that contain the microinverter, the combiner box, IQ cables and the IQ Envoy system for energy management purposes.
The ultimate release, the IQ 7X, is able to work with 96 cell PV modules and can reach up to 435 W and 80V DC modules.
The IQ 8 Model – The Context
Enphase has now announced the upcoming release of the new IQ 8 system with a very promising feature that many solar installers and users are eager to test.
In order to understand the importance of this new release, we must first see it in the context of the current limitations of the Enphase microinverter system.
Firstly, the Enphase microinverter is currently intended to be a grid-tied system.
What does that mean? Well, similar to other grid-tied inverter brands such as Fronius, when the grid fails, the solar system will shut itself down.
There are two reasons for this shutdown.
The technical reason is that the grid acts as a huge energy storage device for the solar system. In other words, if the solar system is not able to provide all the energy required by the load of the house, the grid supplies the missing energy. therefore the system would not be suitable to work on its own.
The second reason is related to the security of the technicians from the utility service company. When there is a failure in the grid, the technicians are likely to be in contact with the distribution lines, which are supposed to be de-energized.
If your solar system is still connected to the grid, they could suffer an electric shock. This is why it is a requirement that the system disconnects itself from the grid when there is a failure.
So far, all the microinverters from Enphase follow this course of action.
In this sense, in the face of a storm or hurricane that causes any blackout, the microinverter would automatically reduce the output voltage of the modules to zero leaving you without power as with any other grid-tied system.
Moreover, people often assume that the AC Battery System from Enphase is a solution to this situation - supplying them with power during blackout conditions. The truth is, it isn’t.
The energy storage solution from Enphase consists of an AC battery of Lithium Iron Phosphate (LFP) with a utility-interactive inverter and a battery management system incorporated of 1.2kWh.
The battery is designed for two main applications:
Under this scenario, the homeowner stores the energy generated from the PV source in the AC battery of Enphase for later use across the day.
Here, PV energy can be exported to the grid, but in Australia it might not be the applied solution due to high electricity rates and low feed-in tariff values.
So the solution would be to store the generated energy for later use.
2. Time Of Use Bill Management
Here the system stores energy generated by the PV system during the day when electricity rates are low and uses it at night when the electricity rates are higher.
The idea is that homeowners shift energy demand away from the electricity provided by the utility when it is more expensive and uses their generated PV energy instead.
As you can see, the Enphase Storage System is not intended to act as a backup solution or off-grid application of solar systems by itself.
As a repeated request from solar designers regarding this limitation, Enphase included in the IQ 7 system the possibility of working in an AC-coupled solution with a battery-based inverter with its separated battery bank.
Nevertheless, the solution is separated from Enphase and requires several manufacturers mixed into a communication system that works mainly with Enphase products, which could present compatibility issues.
The IQ 8 – The Big Release
Now that you are aware of all the features and limitations of the Enphase system, you may ask the question:
What is the big deal with the IQ 8?
The IQ 8 system involves improving the electronics of the microinverter model as in previous versions, meaning more power, adaptability to different modules or energy management features. But that’s not all.
The release of the IQ 8 actually means a change in how Enphase modifies the solar industry. It also means it has access to new markets with all the benefits and challenges that implies.
The reason is that the IQ 8 system will be the first solar solution from the company to work independently from the grid with a complete energy storage solution. It will be able to provide backup and off-grid systems to the whole market, enabling any homeowner that installs it to have their own microgrid.
It will also transform Enphase into the first company to provide a complete integrated solar system with the ability to provide all types of solar systems with the devices from a single company, all of them integrated to provide the most reliable solution in the microinverter market.
This new feature will allow new market opportunities for Enphase as the African market is technically an off-grid type and the Indian market is a weak-grid market. Therefore, with the new slogan of “providing resilience to the grid” it is likely that the new release will start in Q1 2019 in Africa and India as stated by the CEO of Enphase Badri Kothandaraman.
What Will The IQ 8 System Be Like?
The key feature of the IQ 8 will be a brand new technology developed in Enphase, named Ensemble.
The Ensemble system bases its functionality in the IEEE 1547, IEEE 2030.7 and 2030.8 standards, all of them related to the implementation of voltage and frequency drop and micro-grid control structures.
Taking these standards as a reference, Enphase developed an 8th generation hardware microinverter based on a technology known as the Swift ASIC (Application-Specific Integrated Circuit) that performs all the grid control on a single chip.
The microinverter will be able to perform at 295 VA and up to 450 VA during an overload with application for starting motors for example, where a high demand of current is instantly needed.
Moreover, the microinverter will be 97% efficient and will be able to work as a bidirectional inverter - able to transform DC into AC and also AC into DC. That allows it to provide energy from the PV array to the load or to charge and discharge the batteries.
Regarding some other technical advances for solar geeks out there, the IQ 8 will be able to improve the THD power factor on transformers and even dampen sub-cycle harmonics, which are all interesting benefits to the grid.
Moreover, the IQ 8 uses a hierarchical control with three levels:
1. The primary control which is strictly related to voltage and frequency stability of the system with an incredible speed of 100 kHz.
2. The secondary control is related to keeping the power quality according to standards at a much slower speed of 1 Hz.
3. And finally, the third level of control relates to the economic optimization of the system, which is updated every 5 minutes. This will adjust the power flow according to economic benefits or requests from the user or the grid operator.
In order to keep the voltage and frequency control, the system needs to include at least 6 microinverters to supply a typical household.
The IQ 8 keeps all of its predecessors’ benefits (explained above) while at the same time providing a more robust and flexible system, under which expansion of the system can be performed at any time by simply adding more microinverters. Storage can be added at any time by adding the battery coupled microinverters (IQ 8 microinverters destined to merely charge and discharge the AC batteries from Enphase).
The IQ 8 system would consist of a solar array (from another manufacturer) with its microinverters attached to the roof, a storage component, an energy hub (monitor of power flow in the point of interconnection with an Ethernet interface), a remote management system and finally a device that will help you control your consumption.
Enphase’s upcoming release has been awaited for quite some time, especially in countries with weak grids, as the principal limitation of energy storage would be eliminated and changed by the first microinverter system that can autonomously backup your house.
This will transform Enphase into the first company that offers a complete solution (except for the modules) to the solar industry while at the same time doing it with the unique characteristic of the Enphase product.
With the release of the IQ 8, Enphase will still have to compete with other remarkable energy storage solutions such as Tesla Powerwall 2.0, LG Chem RESU and Sonnen Eco, but will have no competition in the microinverter market.
Finally, another crucial matter in the selection of a PV system from a particular brand is the expected lifetime of the system, and in this aspect, the Enphase IQ 8 system does not disappoint either, as a 20-year warranty on the microinverter and a 10-year warranty on the AC battery are expected.
With all these great features, we expect the IQ 8 to have a major impact on the off-grid and backup market worldwide.
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Photo credit: Enphase