Microinverter & Power Optimizer options
More solar installers are beginning to offer module-level power equipment (MLPE) technologies as an alternative to conventional ‘string’ inverters. There are essentially two MLPE options that you may come across if you are shopping for a solar system:Microinverters and power optimizers.
Both solutions offer similar benefits: better performance when your solar panels are in shade for part of the day or at odd angles to one another, and the ability to monitor the performance of individual panels. At the same time, solar systems that use these technologies tend to be more expensive than those that use string inverters.
Here we take a look at the leading manufacturers of microinverters and power optimizers who supply the US market: Enphase and SolarBridge/SunPower (who make microinverters), and Tigo Energy and SolarEdge (who make power optimizers). How are they different and why should it matter to you?
Keep in mind that our analysis is by no means comprehensive - the MLPE industry is growing rapidly, and many new companies now offer or will soon offer their own solutions. That being said, the three largest companies (Enphase, SolarEdge and Tigo) comprise nearly 90% of the market.
Key takeaways: Microinverter & power optimizer options
Microinverter manufacturers
Microinverters perform the same function that a centralized string inverter does: They convert the DC electricity from your solar panels into appliance-friendly AC electricity. The main difference is that there is one inverter per panel with a microinverter system, so the panels operate independently of one another.
Enphase (Headquarters: California)
Enphase Energy is the largest microinverter manufacturer in the US, with a 37% share of the residential market in 2014.
Enphase’s microinverters are mounted on the racking behind your solar panels. There is one mircoinverter per panel. They are compatible with many solar panel brands and models, and it is therefore possible to ‘mix and match’ their products with various panels.
Want to learn more about Enphase? Check out Enphase’s profile on EnergySage, ordiscuss them in our Q&A Forum.
SolarBridge / SunPower (Headquarters: California)
Although a much smaller player in the US residential space (less than 1% of the market in 2014), SolarBridge is noteworthy for having recently been acquired by SunPower, which is one of the largest solar panel manufacturers in the United States.
SolarBridge’s microinverters are designed for integration into solar panels to create ‘Smart Modules’. It is unclear whether they will continue to partner with module manufacturers other than SunPower since their acquisition.
Want to learn more about SolarBridge? Check out SolarBridge's profile on EnergySage, or discuss them in our Q&A Forum.
Other microinverter manufacturers
String inverter & panel manufacturers who also make microinverters
- ABB / Power-One (Headquarters: Switzerland)
- SMA (Headquarters: Germany)
- Altenergy Power Systems (Headquarters: China)
- Samil Power - (Headquarters: China)
- Advanced Energy / Refusol - (Headquarters: Colorado)
- CyboEnergy (Headquarters: California)
- ReneSola (Headquarters: China - mainly a solar panel manufacturer)
Microinverter specialists
- Enecsys (Headquarters: UK)
- Petra Solar (Headquarters: New Jersey)
- Chilicon Power (HQ: California)
- SPARQ Systems (Headquarters: Ontario, Canada)
- iEnergy (Headquarters: Taiwan)
- Involar - (Headquarters: China)
- Lead solar - (Headquarters: China)
Questions about any of these companies? Look up their profiles on the EnergySageSupplier Search, or discuss them in our Q&A Forum.
Power optimizer manufacturers
Solar systems that use power optimizers also have one device per panel, so that the power from each can be ‘conditioned’ individually, thereby maximizing overall system performance. However, unlike with microinverters, systems that use power optimizers still require a central inverter to turn the DC electricity into AC.
SolarEdge (Headquarters: California)
SolarEdge is the global leader in power optimizers, and accounted for roughly 20% of the US residential inverter market in the first half of 2014. The company’s optimizers are designed to be used with its proprietary string inverters.
Want to learn more about SolarEdge? Check out SolarEdge's profile on EnergySage, ordiscuss them in our Q&A Forum.
Tigo Energy (Headquarters: California)
Tigo Energy provides a platform to enable manufacturers of both inverters and solar panels to take advantage of the benefits of its optimizers. According to the company, Tigo’s residential market share was about 10% in 2014.
Want to learn more about Tigo Energy? Check out Tigo's profile on EnergySage, ordiscuss them in our Q&A Forum.
Ampt (Headquarters: Colorado)
Ampt is primarily a manufacturer of 'string optimizers' for the commercial and large-scale solar markets. The company also has a panel-level optimizer product for the residential solar market, which is compatible with a range of brand-name inverters.
Do you really need microinverters or optimizers?
Microinverters and power optimizers: Key metrics
If you have decided that a solar system that uses MLPE equipment is the right choice for your home, the next step is to decide which company’s products best suit your needs. This next section takes a look at the key metrics for comparing microinverter and power optimizers products, as well as how the major manufacturers’ offerings stack up against one another. The three most important things consider when choosing a product are: 1) warranty duration, 2) operating temperature range and 3) efficiency.
Warranty duration
Warranties provide a good indication of the reliability of a company’s products, and are readily available on the websites of most microinverter and optimizer manufacturers. All of the MLPE companies listed below offer a 25 year warranty on their microinverters and optimizers.
While a warranty will cover parts, it may not cover other costs associated with replacement. It is therefore important that you understand exactly how a product’s warranty works: Ask questions about who will pay for shipping and labor in the event that a product needs to be replaced.
Also keep in mind that companies may require other products (communications gateways, inverters, etc) for their systems to function properly. These devices may each have their own separate warranties, generally shorter than those those of the microinverters and power optimizers.
Operating temperature range
The operating temperature range on a microinverter or optimizer’s spec sheet indicates the safe operating range for that product. The range does not refer to ambient temperature around the solar panels, but rather the temperature of the device itself.
Heat causes stress for all electronics, and electronics that are located outside or on top of a building may be particularly vulnerable to the elements. (Cold is less of a concern, and extreme heat is more likely than extreme cold in most US climates.) All of the devices listed below have been engineered to self-ventilate and keep themselves cool, but do produce a small amount of heat during normal operation.
While it is difficult to quantify exactly how a given microinverter or optimizer will fare in the event of extreme heat, as much as possible it is better for them to be kept cool. For this reason, the higher the operational temperature range is, the better.
Peak and weighted efficiency
With respect to microinverters and power optimizers, efficiency is the measure of how well a device converts electricity from one form to another. In the case of microinverters and string inverters, this refers to converting DC electricity from solar panels into AC electricity. In the case of power optimizers, it refers to the conversion of DC electricity from one voltage to another before it is sent to an inverter for DC-AC conversion.
‘Peak efficiency’ refers to how well a device performs ideal conditions - when your solar panels are producing power at their maximum capacity. It is a useful figure for gaining an understanding of how much - or how little - power is lost during conversion. You can compare peak efficiency to the maximum miles-per-gallon fuel economy of a car.
Weighted efficiency is a more sophisticated approach to measuring an inverter’s performance. Weighted efficiency takes into account fluctuations in solar panel output throughout the day (e.g. the fact that solar panels produce less power at 7am than they do at noon). Weighted efficiency is therefore an indicator of how well an inverter will perform in the field, and therefore how much more electricity you can expect your solar system to produce. Again, with the car fuel economy analogy: You get better gas mileage on the highway than you do in the city. You can think of weighted efficiency as being like an average fuel economy calculated using the fuel economies of various driving situations.
Weighted efficiency for inverters can be calculated using different formulas that have biases towards heat or cold. The California Energy Commission (CEC) developed one commonly used method specifically for inverters; it does not apply to power optimizers. Instead, power optimizer manufacturers will usually display a weighted efficiency figure on their products’ spreadsheets based on a calculation they have developed internally.
All power optimizer systems still need a central inverter, so in order to meaningfully compare the efficiency of microinverters to power optimizers, it is necessary to look at the efficiency of the system as a whole - inverter and optimizers. This can be done by multiplying optimizer efficiency by inverter efficiency (e.g. 98.8% x 97% = 95.8%), or by asking your solar installer.
In practice, if the peak or weighted efficiencies of one microinverter or power optimizer product are very close (e.g. 97% vs 98%) there is unlikely to be a significant difference in electricity yield in real life operation.
https://www.energysage.com/solar/101/microinverter-power-optimizer-options
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