Enphase Energy Micro-Inverter

[Mike90250]

Emphase requires one solar panel and one Emphase inverter. Common sense dictates Emphase is more reliable.

Statistics lie.

Unless Enphase has OUTSTANDING QA, and beyond space age technology, I don't see how they can state "Mean Time Between Failure (MTBF) of 331 years". ( 2,899,560 hours)

http://www.enphaseenergy.com/products/products/micro-inverter.cfm

( oh, wait, they say "someone else said it" )

http://www.enphaseenergy.com/downloads/Enphase_WhitePaper_Reliability_of_Enphase_Micro-inverters.pdf

MTBF is obtained by the sum of all the individual internal components, and then wrapped around the final product.


So if they sell 331 inverters, ONE will fail each year.

They do have a 15 year warranty, which is pretty good, if you can meet the requirements.

http://www.enphaseenergy.com/support/enphaseentrust/warranty.cfm

[Mike90250]

Now for another fact. Emphase is a digital inverter. They apear to be very robust in design and performance.

Huh ? Digital inverters ? They may have a digital chip inside that runs them, but I'm fairly sure, if they are Grid-Tie rated, the power section is analog, to generate a grid quality sine wave.

I can assure you that a good chunk of the Xantrex GT series inverters, is "digital" (all the controls).

[Off Grid Solar]

Inverters are a good subject. First let me say this. If you take a whole bunch of solar panels and connect them to one inverter it works until the one and only inverter fails. These type of inverters are analog in nature. Emphase requires one solar panel and one Emphase inverter. Common sense dictates Emphase is more reliable. If a Emphase inverter fails you loose a little power. The single inverter fails and the whole system is down. Now for another fact. Emphase is a digital inverter. They apear to be very robust in design and performance. It is up to you. I will be talking to Emphase soon and then I can answer more of your questions.

[Frank in PG]

Yes, is anyone on this forum using these microinverters? I'm in the process of assembling a few DIY panels and I'm wondering if these will be compatible. Hoping to make 4 18v 60w panels. Whether those work or not, I'll have to wait and see...
So could 4 of these be wired together in parallel into one microinverter, and then expand on that with some professionally built panels later?
Thanks,
Frank

Enphase inverters work. This inverter connects directly to one solar panel. To me this type of inverter is better than a whole bunch of solar panels to one inverter. The reason is simple. If you only have one inverter and it fails for some reason. No more electric power. Enphase if one goes out you still have electric power. Simple!

How do the costs compare, for say a 2Kw system with the micro-inverters in the panels, compared to a 2Kw system with one 2200w inverter?

[Off Grid Solar]

Enphase inverters work. This inverter connects directly to one solar panel. To me this type of inverter is better than a whole bunch of solar panels to one inverter. The reason is simple. If you only have one inverter and it fails for some reason. No more electric power. Enphase if one goes out you still have electric power. Simple!

[sdtvmark]

Hi all!

I am new to the group and I was asked to join to post a copy of my evaluation of grid tie inverters as noted below, of which I describe the benefits of using a micro inverter for some applications.

I just came back from Las Vegas where I attended a conference on grid-tie inverters. The manufacturers that were present were Sunny Boy (SMA), Fronius, Solectra and Enphase. All good products, I must say.

I went to the meeting thinking of using the Enphase product along with the Sanyo HIT 'D' double sided panel for my patio roof project. I like the Sanyo Double panel because it lets about 10% of the light through, so I dont end up with a dark patio. The Enphase product was important to me because I could install half the system now and the other half later, thus saving some start-up build cost. The Enphase Micro inverter allows for easy system expansion.

I think all of the centralized inverters are all good, so it is hard to say which one is better. The SMA products are better known, so they have better market share.

I like the Fronius design because the inverter part separates from the wiring disconnect easy, so a replacement inverter, should one be needed, is a snap to replace. It has clean air flow in a good gasketed enclosure, also it looks cool!

The Solectria product is also good, for the hart if the design is based from an electric car inverter design they brought over from the Solectria Electric Car, that was sold off to Azure Dynamics. A solid and proven design, American made and used often in larger commercial installations of 60 and 100 KW. They also have a nifty 1 to 3KW inverter that lends itself for household use.

All the inverter companies seem to have an internet based monitoring system. Some better than others. The Solar Edge company you recommended seem to have a combination PV panel mounted PPT solution along with a specialized inverter. This system allows each panel to be optimised by the Power Point Tracking that regulates and optimizes the best point on the current and voltage curve of each panel.

All PV inverters now a days have some sort of (PPT) Power Point Tracking. The advantage to look at is can one PPT on a string of panels or each panel individually. So PPT on a string of panels is not as good as PPT on EACH panel, by a gain of a few percent.

Also to consider, on a string of panels you can get some real energy losses just by some partial shading from anything. Like the Christmass string of lights with the one bad bulb, making the whole string not work well. So by having a device on every panel you can minalize the whole string loss effect. The Solar Edge or the Enphase micro inverter one can miamise shading problems and still have PPT for each panel.

To correct problems with existing systems from shading, one can simply install the Solar Magic box to the shaded panels. Just as you recommended, this seems like it would correct the problem in a string situation. This device cost about $200 I think, just as much as a Enphase micro inverter!

Talking about Enphase, they seem to have a manufacturing problem keeping up with demand as they switch the manufacturing base to become more global. Also with the Enphase product there is no need to have a wall hung inverter on the side of one's house.
Otherwise all centralized inverters need to be mounted in a shady spot so the stay cool.

The next component of the inverter decision is the web based monatering solutions. This bell and whistle approach to what kind of eye candy one gets with the inverter one picks is important. Some charge a small fee for hosting this information of your system and others do not. Mostly monatering is needed to check on the performance of the system, and some rebate or utilities require it.

I like to be able to see the performance of 'each panel', this helps with troubleshooting. So the Solar Magic system or the Enphase system allows for this. The string or centralized inverters do not.

As with every inverter, panel sizing to match the inverter voltage is most important. You dont want to smoke that expencive component, now do you? So most manufactures have a web based selection tool where you pick the type of panel you want to use, input the coldest typical day at your location (This can cause the panel to make more voltage be being efficient than normal) and the warmest day at your location. You need to be within the operational voltage limitations of the minamum and maximum of the inverter you selct. So one needs to make the PV panel count on each string match as to what is recomended by your inverter specifications.

So, you can see that I have given a thought or two to my PV system design, I may still stick with the Enphase Microinverter, eliminate the need for a combiner panel and DC home runs, or otherwise hang a Fronius on the wall. I do like to be able to ad to the system later and still monitor every panel without worring about the tree shading half the system in the afternoon, a microinverter allows for this.

I also wanted to include supporting information of the trend of PV panels and panel manufacturers moving towards an all inclusive panel with integrated Power Point Tracking (PPT) and enhanced shading corrections, all mounted on the panel itself. Perhaps this is a trend to become the mainstay of PV in the future, or "Plug and Play" PV.

As you may know panel makers like Akeena and Schott have aligned themselves with such PV power correction companies to develop an all in one panel product.

Here are some good supporting links:

http://www.solaredge.com/files/news_pdfs/dow_jones_27_may.pdf

http://beta.technologyreview.com/energy/22661/

http://www.renewableenergyworld.com/...009/02/akeena- enphase-introduce-ac-solar-panels-54665

http://www.solaredge.com/articles/schott-solar

It seems by having this futeristic manufacturing base of plug and play PV panels in the industry will simplify installation for the common home owner, make additions easy, increase the harvest of system energy, lower installed cost and open up an increased use of PV, all a good thing for the world!

Mark

[LeesaLee]

Hi folks,

Thanks for the interest in Enphase products. To provide some input from Enphase:

1) Yes, Enphase products are CSA listed per UL 1741.

2) The temperature question is one that we get a lot. It's logical to be concerned about temperature behind the modules, but it turns out that the temperature rise above ambient is pretty minimal - about 6 degrees F - and much lower than the surface temperature of the PV module and the exposed rooftop. We have a tech brief that describes this - http://www.enphaseenergy.com/downloa...emperature.pdf.

Leesa Lee
Director of Marketing
Enphase Energy, Inc.

[Mike90250]

Healthy Enphase Debate

3) Permits & Approvals:

City building permit. Required if you mount on a permitted building

Electrical permit

Electric Company Approval/Registration - unless you want them to cut you off, you are "affecting" their meter.

And if you add more next year, you have to go through the whole process again.
Or go "Gorilla Solar" and take your chances.

May as well go for a full out 5KW system, the $/watt is much better.

[GoodDaySolar]

Healthy Enphase Debate

Mike,

I don't work for Enphase, but they have all the UL-listing necessary. See the whitepapers at enphaseenergy.com for the dirt.

The inverters are mounted on the rack, not against the back of the panel, so they don't touch the 'hot' panels, in fact, they're semi-protected from the heat by recommended 4" standoffs. It seems like the shade is a better place for inverters than the side of a building.

The company seems to go to great lengths to extend the reliability factor, which is why the warranty is 15-years, longer than most inverters, and they do extensive third-party testing, claiming a 300 year mean failure rate.

Still, you're point is correct, they're not proven in the field. I have to think they're planning to be around longer than 15 years so we can find out.

[Mike90250]

1) are the Enphase Energy Micro-Inverters UL listed? (home insurance)

2) do you really think some electronics package glued to the back side of a sheet
of dark glass (HOT !!) is going to last, or will you be replacing it every 6 years.
Really think on this one folks. Hot days. Cold nights. Winter cold. I can't think of a WORSE place to park the inverter. PV panels are good for 25 years, what if this gadget burns a spot in the back of the PV panel. Who warranties that ?

[GoodDaySolar]

Enphase As Disruptive Technology

FYI, I'm starting up a solar integrator in Boulder using only microinverter technology, because it has multiple advantages.

Like: Scalability, 10-15% less installation labor, integrated performance monitoring options, no large inverter mounted, reliability. And more.

[D_Robbins]

Hey Geoff, I watched the video on their website and it said they can get about 5-25% more efficiency.

[solar_geoff]

There would be certain advantages to this technology in shaded conditions, and also that you would not need to worry about string sizes. With micro inverters shade would only affect the peformance of 1 module at a time. You also would not need to worry about string sizing or keeping all modules per string facing the same pitch/orientation, again because there are no string voltages to worry about. You could just plunk them down on the roof wherever there was room.

I would be curious to see what the efficiency of these inverters are.

[D_Robbins]

thanks for pointing this out, never heard of this company until now. I just checked out their website and saw a video and their product looks promising