HECO solar

How HECO is Using Enphase’s Data to Open its Grid to More Solar

HECO solarOn the island of Oahu, Hawaiian Electric Co. is opening a backlog of about 4,000 customer solar systems it once feared could destabilize its distribution circuits. That move is being helped along by Enphase microinverter data that can provide a much clearer view of what’s really happening on the edges of HECO’s grid.

On Tuesday, Enphase revealed details on a months-long collaboration with HECO to map out how customer-owned rooftop solar affects its distribution grid on a circuit-by-circuit basis. The results have allowed HECO “to clear nearly all of the backlog of customers awaiting approval to interconnect their rooftop solar systems in a safe and reliable manner,” Jim Alberts, the utility’s senior vice president of customer service, said in a prepared statement.

New 3-phase microinverter for large scale applications

markt_pv_new_3-phase_microinverterMicroinverter expert APS is now shipping its new 3-phase YC1000 inverter, which can handle 277/480 grid voltages and up to four PV modules per unit. Up to eleven units can then be linked in a single 15 A circuit.

The maximum output of one YC1000 lies at 900 W and additionally it has integrated ground and features wireless communication via ZigBee. Thereby, the microinverter can be integrated with the APS Monitor to provide real-time data or the APS Communicator for comprehensive performance data, which are accessible via any device with online capability. According to the manufacturer, the YC1000’s price is competitive with that of conventional string inverters.

“With native 3-phase capability in a microinverter package, large-scale commercial customers now have a significantly better solution for distributed rooftop solar,” Paul Barlock, the Senior Vice President at APS America, said.

APS will showcase the YC1000 at booth number 3124 at the Solar Power International conference.

All About Solar Inverters

solar-inverters-line

Solar power in recent years has become completely modular and that is great news for potential system owners. In the olden days, it was necessary to buy not only solar modules but batteries as well. This dramatically increased the cost of your basic system. In 1991 SMA Solar Technology (the world’s largest solar equipment company) produced the first solar “grid-tied inverter.” Solar inverters remain key to all solar projects.

The grid-tied inverter is the piece of equipment which makes it possible to install a solar system on your home without the added cost and complexity of batteries. It is “grid-tied” rather than “battery based” which means it seamlessly connects to the electrical grid your home is already using for power. The “inverter” takes the electricity produced by the solar modules on your roof and makes it directly usable in your home.                                                                                                                                                              

The “Microinverter” Changes the Game

enphase inverter

Fast forward to 2008, Enphase Energy releases the first “microinverter” into the solar market and changes the game. The “microinverter” is exactly what it sounds like, it is a much smaller inverter. It works essentially the same way as its larger forefathers but has made it so you can have a workingsolar system with just one solar module and one microinverter. Each microinverter attaches directly under each solar module in the array   (i.e. if you have 5 solar modules you will have 5 microinverters). Before the microinverter you would have had to buy many solar modules and one larger “central” inverter.

The microinverter has made solar power systems completely modular, not just in their installation and operation but also in their monitoring. As a system owner you want to make sure that your system is operating the way you expect and producing as much electricity from the sun as possible. Enphase has developed a very user-friendly monitoring system that allows you to view the production of every module on your roof on an individual basis. As a system owner you are provided with access to your system’s real-time production information online as well as through an app on your smartphone. This allows you to show friends and colleagues your solar production whether you are at home or a world away.

                                                                                                                                                        

Enphase Enlighten Monitoring Portal and App

enlighten app

Central Inverters vs. Microinverters

As a result of these two different solar inverter options, the question becomes “Which inverter is right for my system?” It all depends on what type of system you want. Professional solar installers are able to help you make the right choice given your system location and size, as well as the goals you want to achieve with your solar installation. Central inverters and microinverters both have their strengths and there is no absolute winner in the contest.

The easiest factor that can help you decide is the system size. If you want to install a very large solar system, it will be more cost effective for you to buy a central inverter. Buying a central inverter for a system with many modules is analogous to buying your inverter power “in bulk.” Similarly, if you only want a few modules on your roof to try solar power before committing to a larger system you would want to buy microinverters. The nice thing about the microinverter is it allows you to easily add onto your existing solar system in the future. You could install 10 solar modules with 10 microinverters this year and next year add 5 more modules and microinverters to have a 15 module solar system. Adding solar modules onto a system with a central inverter is not impossible, but it is more difficult and is not often done in practice.

Benefits of a Central (String) Inverter

The central inverter (also sometimes referred to as a “string” inverter) is tried and true. The central inverter has been the workhorse of the solar industry for many years and is still going strong. In the areas of utility scale (1MW+) and commercial solar (50kW-1MW) central inverters hold 99.9% of the market since they are so much more cost effective on the large scale. In the residential space microinverters have captured a large part of the market, but there is an inflection point where it becomes cheaper to use a central inverter. Here is a rough cost analysis showing the inflection point where a central inverter becomes more cost effective.

The chart shows after 24 modules it is more cost effective to buy a central inverter. A 24 modulesolar system is equivalent to about 6 kilowatts of power and is on the larger side of residential systems. Although these are rough numbers it is a useful rule of thumb when considering the basic system size you want. If you are looking at a larger system on your home a central inverter is probably the right choice for you.

Central (String) Inverter Pros:

  • More cost effective for systems over 6kW
  • Proven technology with robust performance
  • One convenient inverter location

Benefits of Microinverters

Microinverters have many benefits on smaller (less than 6kW) size systems in addition to being more cost effective. Microinverters provide for a simpler installation as well as mitigating design concerns such as orientation and shading. With microinverters you are able to install modules at multiple orientations without experiencing dramatic losses in efficiency.

uniform insatllation

multi direction

                         

If shading is a concern at your site, microinverters are great due to their ability to optimize each module individually. Largely the considerations of system design are not the responsibility of the homeowner and a professional solar installer will help you design the right system for you at a price you can afford.

Microinverter Pros:

  • More cost effective under 6kW
  • Mitigates shading and orientation losses
  • Modular and Expandable in the future
  • Individual module optimization and monitoring

Bill Ehrlich is a Mosaic blog contributor who works in the electrical industry. After graduating from Notre Dame with a degree in Finance he worked on a cattle ranch in Wyoming and then taught English in China. Returning home to the States he worked at Inovateus Solar, a solar integrator in South Bend, Indiana. Originally from Minnesota, he is currently getting his hands dirty doing electrical construction in the city of Chicago. Outside of work Bill enjoys investing, solar power, and most of all, investing in solar power!

Microinverters vs. String Inverters

microinverterr

If you’re a homeowner or an installer doing residential or small scale commercial solar installations, you essentially have three choices for converting the solar system’s DC power into AC power: You can either go with new microinverters or with string inverters—with or without DC power optimizers. All will work, but there are differences, especially in certain situations.

String Inverters: The solar industry standard

The KACO Solar blue planet xi-series inverter design is not only efficient, it also offers patented MPPT technology and produces optimum total output from your installation.

With residential string inverters, all solar modules are connected in a series circuit to a DC electric cable, which is then connected to a single inverter box mounted on a wall by the home’s main AC panel (as well as to any required DC disconnects). So it’s a very centralized system with a limited amount of labor.

Modern string inverters not only convert the power from DC to AC, but also use Maximum Point Power Tracking (MPPT) to deliver the maximum amount of power available. This is important, since each solar panel can produce different amounts of power due to manufacturing anomalies, intermittent shading, leaves, dirt, passing clouds, and/or other factors.

While a string inverter’s MPPT works fairly well, especially in sunny areas with no obstructions, having all solar modules tied in a series circuit can still be a disadvantage for several reasons:

1)   MPPT technology is essentially drawing the average amount of power available, rather than the full amount available from each module. As a result, the entire solar array can lose 15% to 30% or more of its full potential output because one or more panels in the string are temporarily shaded or have debris.

2)   If you have limited roof space and need two arrays with different sun orientations, each array will need its own string inverter.

3)   Similarly, since module mismatch can cause efficiency issues, you’ll need to use the same brand and panel voltage within each string.

4)   String inverters don’t easily allow for expanding the system in the future unless you purposely oversize the inverter, wiring, and other BOS parts.

5)   While it’s common to have online monitoring with string inverters, the monitors only measure the performance of the entire array. So, if an array isn’t producing the expected power, installers will need to individually test each panel for malfunctions.

Tigo-Energy-maximizer_1_large

Designed for residential, commercial and utility scale photovoltaic solar arrays, the Tigo Energy® Maximizer™ system optimizes the power output of each solar panel, delivering module-level data for operational management and performance monitoring.

6)   String inverters are typically warrantied for 10 years and have an expected lifetime of 12 to 15 years, while solar panels typically last 25 years or longer. Thus, the string inverter will need to be replaced at least once.

Adding DC Power Optimizers to String Inverters

Adding DC power optimizers to a string inverter system can solve most of the above string inverter challenges. Power optimizers are relatively new electronic devices that perform MPPT tracking at the module, instead of at the inverter. As a result, optimizers feed the most optimized DC current and voltage for each panel into the string, significantly reducing power and efficiency losses due to shading, module mismatch, etc. Power optimizers also allow you to:

  • Monitor each solar panel for performance and/or troubleshooting.
  • Mix and match solar panels and brands.
  • Have two strings in parallel for one inverter, thus allowing you to combine two arrays facing different directions.
  • More easily expand the system—but only up to the inverter’s power rating and wiring gauge.

Microinverters – Inverters for one solar panel at a time

In many ways, microinverters do all of the things that string inverters do and power optimizers do—all in one small and simple package.

The Enphase Micro-inverter shifts DC to AC conversion from a large, centralized inverter to a compact unit attached directly to each solar module in the power system.

The Enphase Micro-inverter shifts DC to AC conversion from a large, centralized inverter to a compact unit attached directly to each solar module in the power system.

Unlike centralized string inverters, microinverters convert the solar panel’s DC watts into AC watts at the module level and then connect in parallel to the main AC box. While panels with microinverters aren’t exactly “plug and play,” they do make installation and monitoring very simple.

Microinverter advantages include:

1)   MPPT tracking of each solar panel. As with DC optimizers, each solar panel can harvest as much solar power as possible, regardless of the intermittent shading, passing clouds, or the mismatch of other panels in the array.

2)   Individual panel monitoring. If the array isn’t performing as expected, the microinverter monitoring system will show which panel(s) is at fault and can even send you an immediate email alert.

3)   Full modularity. With the correctly sized AC wire gauge, microinverters allow installers to install a small system and easily add more solar panels later. In fact, added future panels can be different brands and different voltages, and they can also be installed at different solar roof orientations.

4)   Easier design and installation. Especially when using pre-mounted micro-inverters or true AC panels, designing and installing a micro-inverter grid tied system can be much easier and faster.

5)   Microinverters are typically warrantied for 25 years. As a result, there shouldn’t be a need to replace the inverters at year 12 or 13.

So what’s not to love about microinverters? A few things to consider:

  • Microinverters are new technology. Yes, the warranties are for 25 years, but microinverters haven’t actually been in the field for that long. If they don’t last that long, depending on the warranty, installers may be responsible for the labor costs to replace each failed microinverter. Thus far, however, microinverters have generally performed well. And don’t forget that DC power optimizers are also new technology.
  • It’s more expensive. Currently, microinverters are more expensive than string inverters for the same sized residential system, and slightly more expensive than a string inverter/power optimizer system. The more panels in the solar system, the more microinverters needed, so the microinverter cost can be significantly higher for larger systems. That being said, microinverter prices are falling gradually.
  • Possibly more labor time. If purchasing microinverters separately from solar panels, installers will have to spend more time attaching each microinverter to the solar panel. Meanwhile, a string inverter can mount fairly easily to a wall.
  • Multiple failure points. This could be an advantage or disadvantage. If a string inverter goes down, the entire solar system goes down. If a single microinverter goes down, no big deal. Then again, if a lot of microinverters go down at once…there will be a great deal of labor cost replacing them. But once again, to date, there have been no reported mass failures or recalls of microinverters.

Bottom line, both microinverters and string inverters with or without optimizers work well, but each has its own set of risks and advantages. Choose the technology that’s right for your insolation, budget, and size.

Original Article on Go Green Solar

Micro Inverters: What You Need to Know

Are you thinking about installing solar panels on your home or business? You may just want to update your current system and add value to your investment. There are two types of inverters that you can install on your solar panel array. These may be either an array inverter, which will convert the DC current on your set up to AC, but it is less efficient than micro inverters. A micro inverter can convert the DC current on one or two panels. This will help you in getting the maximum efficiency out of your solar installation.

Getting Started With Micro Inverters on Your Solar System

It has been two decades since the first micro inverter was fabricated, and in this time there have been vast improvements. Now, you can find micro inverters for several types of set ups. These inverters can be linked to an internet gateway to help you monitor the efficiency of your solar array.

You can use a unit that connects a 60 cell unit, such as, the APS YC200 micro inverter. There are also others like the Enecsys micro inverter, which can handle some extreme temperatures and is a little more robust than the APS YC200 micro inverter, though not as cost effective.

If you want to have the internet monitoring capabilities you will also have to have an Internet Gateway Module. Both APS and Enecsys have Internet Gateway Modules for monitoring the efficiency and performance of your solar array. The units will allow you to access the statics of your system from any Internet connection and monitor performance and see any potential maintenance problems.

Getting Your Micro Inverters Connected to Your Grid

Once you have decided on the system that you want to implement, you will be ready to start the process of installation. It will be easiest if it is a new installation and you are mounting them on the racks as you go. You can string up to 15 can be daisy-chained together per string. What does this mean? This means that you can connect up to 15 units to connect to your power grid.

When you are installing the inverters and any other electrical equipment you want to make sure that there is no current, and that all power is disconnected from energy sources. You will need the cable, and connecting points to mount a daisy chain of micro inverters to your solar panels and disconnect switch.

First you will want to mount the micro inverters on the racks and run the cable and connections that you will need for each individual micro inverter. After the cables and micro inverters have been installed you will be able to start with connecting it to the disconnect switch, but if you want to have an Internet Gateway the module will need to be mounted before it is connected to the disconnect switch and meter.

The Internet Gateway can be mounted and connected to an array of panels and to the disconnect switch and meter. There are cable and wireless Internet Gateway modules that can be mounted to give you the information of the solar array you have setup.

If are using wireless; you will probably need to use a range extender that is connected to the solar panel array. In addition a wired Internet Gateway Module will need to have CAT5 cable to connect it to the internet.

You may even be able to return energy that you do not use back to the power grid of the power company with a Gird Tie Inverter, and save even more on your energy costs.

Original Article on Greener.Ideal

PV Inverters Market: 52.3 Gigawatts by 2018

Soaring oil prices and growing environmental concerns intensified the focus on alternate energy in recent times. The photovoltaic industry is a major benefactor of this growing interest, with large scale solar parks mushrooming in advanced and developing countries alike, propelled by favorable regulatory environment, Government subsidies, falling PV module prices, and the growing pressure on buyer rates. In particular, the feed-in-tariff (FIT) and micro-FIT programs in several countries, particularly Europe, reaped rich dividends in the form of increased solar installations. As a result, PV system installations grew at a healthy rate of over 30% over the last decade and are expected to continue at a robust pace through the year 2020, fostering a similar increase in demand for PV system components such as inverters.

While Europe remained the major growth driver for the global photovoltaic industry for most of the previous decade, the announcements of roll-backs in FIT subsidies created shockwaves that rippled throughout the worldwide supply chain. The Spanish Government triggered the trend in 2008, announcing deadlines for cut-backs in FIT incentives. With other Governments following suit, the unprecedented surge in demand drove a short term spurt in prices in 2010. The Eurozone crisis is expected to stifle regional Government support for solar installations in the near term, weighing heavily on the global market. At the same time, US Government is showing renewed interest in solar photovoltaic power, as part of its ‘green economy’ drive. The recent nuclear incident at the Fukushima plant prompted the Japanese Government to revisit its alternate energy infrastructure.

Photovoltaic Inverters are transforming from simple energy conversion devices into ‘Smart’ PV inverters with capabilities of intelligent energy storage and grid interaction, and reactive power that are fast becoming a core part of the fast expanding smart grid infrastructure. Due to issues related to grid imbalances factors such as increasing deployment of grid-tied PV inverters, the need for intelligent energy storage and disbursal systems and integration of solar power into the utility grid are driving demand for ‘smart’ PV inverters. Moreover, regulators are tightening inverter specifications and demanding that PV inverters play a greater role in grid stabilization, thereby improving the scenario for smart PV inverters in developed markets. Germany set the example for other European countries, by issuing the Low and Medium Voltage Directives for integrating solar power into the utility grid. The implementation of this directive is expected to propel the market share of smart and semi-smart PV inverters. In the medium-term, energy inverters are expected to constitute about half of the total of PV Inverter shipments, driven by Government subsidies and the development of cost-effective alternatives for the expensive lithium ion batteries in widespread use at present.

PV inverter manufacturers are displaying increasing propensity for disruptive technologies, as is evident from the huge growth in shipment volumes of microinverters and power optimizers in 2010. DC-to-DC power optimizers and solar microinverters are expected to cross the $1.0 billion mark in terms of revenues over the next few years, with shipments also projected to double over the period. These technologies offer enhanced power harvest besides enabling easier installation, improved monitoring and safety. Microinverters offer benefits for PV systems that are prone to shading and require constant re-orientation, as well as overcoming the single-point failure of central inverters. While solar microinverters are anticipated to find application in residential and commercial applications, power optimizers would be employed in large scale commercial projects that involve the deployment of central inverters. Despite this, the segment accounts for a fraction of the total PV inverter market, with penetration limited to less than 10% of the total market. The substantially high prices and technological immaturity of microinverters are the greatest barriers to their adoption, particularly in commercial applications. However, prices of the disruptive technologies are sliding downwards, as scales of economies are being realized through OEM contract agreements.

Europe dominates the worldwide PV Inverters market, as stated by the new market research report. The European market, led by Germany, France, Italy, Spain, Belgium, Greece and the Czech Republic, also accounts for the majority of the global installations. However, in light of the economic recession and subsequent Eurozone financial crisis, several Governments rolled back PV subsidies and incentives as part of their austerity measures, thereby culling demand in the region. In the near term, China and India are forecast to emerge as major centers of growth in the Asia-Pacific region, with China evolving into a major PV inverter manufacturing hub for the region. Government authorities in emerging Asia economies are also promoting PV system installation, driving the domestic demand for solar inverters. As a result, the market is expected to register healthy CAGR of over 25% through 2018.

Original Article on PVdepot.com

True Sine Wave or Modified Sine Wave Inverters?

Because the AC electricity from the electric grid is in the form of sine wave, the inverters we use aim to produce a current that is as close to sine wave as possible.  While modified sine wave inverters present an inexpensive alternative, there is no comparison to the clean, undistorted sine wave provided by pure sine wave inverters.

A pure sine wave inverter, also known as a true sine wave inverter, produces a clean, undistorted electrical output.  Depending on the manufacturer of the product, pure sine inverters have a perfect sine wave output that’s in phase with the AC grid of the utility company.  Because of the sinusoidal form, pure sine wave inverters are used for grid-tie solar systems and work for virtually any AC load.
 
Cotek SK3000-148, 3000 Watt 48V Pure Sine Wave Inverter

Because they produce no harmonic distortions in the frequency, pure sine wave inverters allow any electronic device to function well without overheating or creating an irritating “buzz” sound.  Though pure sine wave inverters are undoubtedly the best and most versatile kind of inverter, they are more expensive than modified sine wave inverters.

Pure sine wave inverters are necessary for highly sensitive products such as digital clocks, audio equipment, and video-game consoles.  As a general rule of thumb, if you’re powering any electronics, you’ll probably want to stick with a pure sine wave inverter.

The image below displays the difference between a pure sine wave and a modified sine wave.

The cheaper alternative to a pure sine wave inverter is a modified sine wave inverter.  A modified sine inverter converts DC electricity to a nonsinusoidal AC wave that is “modified,” or distorted.   When an inverter produces modified sine wave, the voltage output (represented in the Y axis of the image) essentially jumps from zero volts to positive, where it plateaus and drops back to zero, to negative voltage, and then back to zero again. This is signified in the image by the squared edges seen in the modified sine wave, which is contrasted by the smooth oscillation of a voltage that is produced by a pure sine wave inverter.  The modified sine wave is a stepped waveform that is designed to mimic a true sine wave.  Because it is not a clean form of energy, modified sine wave does generate a certain kind of interference called harmonic distortion (though not as much as a square wave).

Modified sine wave inverters can work for the majority of low-end appliances, but take caution when using them for your electronic devices.  Because these inverters do not produce a clean output, a “buzz” often accompanies modified sine wave inverters.  Highly sensitive electronic products that were intended operate with a clean AC waveform will certainly overheat when connected to a modified sine wave inverter.  Since modified sine wave inverters are less efficient than pure sine wave inverters, the excess energy produces heat that can be detrimental to some devices.  The impure energy produced by modified sine wave inverters can curtail the longevity of many appliances, and utterly destroy some electronics that were originally designed for clean AC.

Samlex America PSE-12125A, 1250 Watt 12V Modified Sine Wave Inverter

Though it would be wise to choose a pure sine wave inverter for a television, video-game console, or audio equipment (so they don’t overheat), a modified sine wave inverter is suitable for most rugged, low-end products.  At such a low cost, it makes financial sense to use a modified sine wave inverter if your equipment can handle it.
If your goal is merely to power some lights and a refrigerator, a modified sine wave inverter will surely satisfy your needs.  If there’s even a chance that you will be powering sensitive electronics with your inverter, opting for a pure sine wave inverter is highly recommended.  Don’t stress over what is compatible- with pure sine wave inverters, there is no hassle, no interference, no noise, and a longer lifetime for your appliances.

What are your thoughts on modified sine wave inverters?

_______________
Thomas Jackson
www.gogreensolar.com

Original Article on Go Green Solar

Microinverters vs. Central Inverters

So you’re installing a brand new solar system.  Do you go with microinverters or stick with a central inverter?

What’s the function of an inverter?
The task of an inverter is to convert direct current (DC) to alternating current (AC), which is needed for the vast majority of electrical devices.   Solar energy comes in the form of direct current, which must be converted to AC for this reason.
Central Inverter
Traditionally, central inverters have been used in solar systems to convert DC to AC.  One central inverter is connected to multiple solar panels.
Central inverters are trusted by many because they have been around for so many years and people are familiar with them.  This technology has been around longer, so the collective amount of real-world use gives central inverters a certain kind of credibility in the industry.

SMA SB 3000US Sunny Boy Grid Tie Inverter 3250W with DC disconnect

The key benefit of a central inverter is cost.  The bottom line is that central inverters currently cost less per watt than microinverters.  This is why many home owners and most utility scale industrial applications opt for central inverters.  A good number of people argue that having a single conversion point simplifies grid management for such large applications.

Critics of central inverters point out that high voltage levels are centralized with these inverters and thus pose a safety hazard.
The main disadvantage of having a central inverter is that your system is “only as strong as its weakest link.”  If one panel is subject to shading or some other form of coverage, the energy output of your array can be decreased by fifty percent.  This setback has created an opportunity for microinverters to make their way into the market.
Microinverters 
Microinverters convert the DC electricity from each panel to AC electricity.  They attach behind individual solar panels in the array, allowing each module to operate independently.  Microinverters can maximize the power produced by each panel, rather optimizing for the “weakest link” in an array.  Because of this, microinverters are particularly advantageous for systems in locations that might have shading or some form of coverage (i.e. dirt, snow, etc).
Using microinverters definitely has its advantages, predominantly for residential applications.  Microinverters, such as the Enphase M215 on the right, are desirable for DIY applications because they’re so easily installed.  Microinverters are easily scalable, meaning you can add to your existing system with little trouble.  Microinverters also allow for module level monitoring and comprehensive analytics, making it possible for you to view how much energy is being produced by each panel.  For these reasons, microinverters have become increasingly popular for residential applications, particularly in California.
The main disadvantage of microinverters is the price tag; they still cost more per watt than central inverters.  Dual microinverters have been introduced to address this issue.  Because dual microinverters connect with two panels at once, the cost per watt is cheaper than single microinverters.

Currently, Enphase Energy dominates the market for microinverters.  Enphase offers a fifteen year warranty on their microinverters.  Over the last several years, Enphase microinverters have made a remarkable breakthrough in the solar market.  Many believe that microinverter technology will continue to gain traction in the years to come.

What do you think?

As microinverters (and dual microinverters) become cheaper, what can we expect to see?  If microinverters become cheaper than central inverters, will central inverters eventually become obsolete?  Perhaps there will continue to be a place for both technologies, each with their respective applications.  I guess we’ll just have to wait and see!

Original Article on Go Green Solar