single inverters vs micro-inverters

[coffeepodman]

İ didn't realize 'faith' was an engineering term?

They have done their best analysis that says (either or both):
1) Proper engineering analysis has been done - now we hope and pray
2) This is what we have to have to get into the market and by the time the failures start to come we will have come up with a defense.

Warranties only count from companies that still exist at (after) the time of failure. That excludes probably 90% of the companies in the solar field today.

Russ - perhaps faith is not the best choice of words -- perhaps I should have said confidence .. I have confidence in Enphase .. they just opened a facility here in Ontario to manufacture for the Canadian Market .. now I think I can say that is either faith or confidence or a commitment. .. It's also too bad we have to adopt an attitude of plausible denial about every thing or figure out an excuse in advance of a problem... SO ..for example ! why not be honest and admit you had problems with the BLOW OUT PREVENTOR and make sure it doesn't happen again ! now that's engineering.

[russ]

@coffeepodman - Greetings and for your information İ live in neither the US or the UK. The BOP problem you manage to sneak in is a BP problem which last İ heard stands for British Petroleum. Probably not an engineering problem really but a management problem in drilling where they should have never gone - too deep when the technology doesn't exist to support the program.

Ontario will still be paying for the trip into fantasy land on RE when your grandkids have to foot the bill. Enjoy! The FİT is far too high to be sustainable and these companies showed up due to guarantees on things like no taxes for many years? free or cheap land? and many other assurances/guarantees.

İ see no big rush to accept a new technology based on a companies words. Those words will, almost certainly, be self serving and not necessairly have anything to do with the truth.

Enphase may work out fine time will tell.

[coffeepodman]

No Taxes ?

The Ontario Government has not promised anything like free land or no taxes ... actually they will gain ..the risk will be born by the producer and the power authority will benefit by not having to put in place so much expensive infrastructure ... that's why they are giving 80.2 cents per kW !

The pay back on a Tracker System is 5.5 years with the contract for 20 ... better than a GIC or stocks ( little risk) and the banks are chomping at the bit to lend against a contract from OPA / Ontario Hydro.

The Ontario Content restrictions bring Jobs to Ontario and discourage import of off shore product. Some think that's a good idea.

[russ]

Could be but İ expect that if you know the deals details you would learn different.

All big companies are looking for their own incentives when they locate a major facility - this time is no different and certainly other locations would be offering deals.

İn the present economic difficulties and with states/provinces wanting job creation landing a big one like Ontario has is not cheap or easy.

The local content part is causing a bit of a problem for guys İ know. That will get sorted out in a sort time no doubt but installers are learning what all is not locally available.

[coffeepodman]

we are getting off the thread

Before we get back on the thread ... perhaps it's prudent to remind our readers that the OPA contract of 80.2 cents per kW is only for now and until the end of 2011 .... any one care to speculate what it will be offered at in 2012 ?

If the world doesn't come to an end ... thank you Mayan's

[Naptown]

there is a new report out

http://www.renewableenergyworld.com/rea/blog/post/2010/04/micro-inverter-misconceptions?cmpid=rss

about central / micro inverters

Written by a string inverter manufacturer.
What did you think they were going to say?

[Sunking]

Written by a string inverter manufacturer.
What did you think they were going to say?

While the article was written by KACO with some bias, I tend to agree with most of the opinions. Micro inverters have their place with shading, odd tilt and direction orientation, and mixed panels issues, but when it comes to cost and high failure rates it just does not add up for most applications.

[Naptown]

Do you have documentation on the high failure rates?
We've installed hundreds and had one failure and that was on start up so it was a defective unit from the factory not a failure per se.
As far as cost goes pretty much anything below 2KW is more cost efficient with the micro inverters. I would have to be above 5 KW before the cost tips substantially in favor of the string. Add in a sunny portal or other monitoring system and the margin becomes even smaller.

That said we do not use 185W modules, standard module is in the 220-240W range. Enphase cost me about $150.00 each That puts the inverter cost around $.65 a watt.
In many jurisdictions it also allows me to run romex through the house instead of pipe down the oustide which reduces installation costs.

As I alluded to in another thread we also have problems with trees different directions etc on our installations. It also does not get as hot here as in Texas so over heating is not as much of an issue for us as it might be for you.

[Mr. Mik]

Is the information on Wikipedia about microinverters accurate?

http://en.wikipedia.org/wiki/Solar_micro-inverter

[silverhorsefarm]

The MD Public Service Commission gave me a higher derate factor for having micros, which translates into higher harvest estimates, which, in turn, translates into more SRECs/year that I can sell. It's a modest difference, but it adds up over 15 years.

[Mike90250]

Is the information on Wikipedia about microinverters accurate?

http://en.wikipedia.org/wiki/Solar_micro-inverter

This part is:
Microinverters have several advantages over conventional devices; they eliminate high voltage DC runs, reduce line losses, individually control the panels output and act as maximum power point trackers, and introduce redundancy to the array.
Their primary disadvantages are that they are generally more expensive than the equivalent string inverter, and are normally located on the panel, where they may be harder to maintain.


and the rest of it is pretty good too. I still don't like them for installs in good conditions, but for solving a problem in marginal installs, they work.

[Sunking]

This part is:
Microinverters have several advantages over conventional devices; they eliminate high voltage DC runs, reduce line losses, individually control the panels output and act as maximum power point trackers, and introduce redundancy to the array.
Their primary disadvantages are that they are generally more expensive than the equivalent string inverter, and are normally located on the panel, where they may be harder to maintain.


and the rest of it is pretty good too. I still don't like them for installs in good conditions, but for solving a problem in marginal installs, they work.

Pretty good assessment, it depends.

[Sunking]

The MD Public Service Commission gave me a higher derate factor for having micros, which translates into higher harvest estimates, which, in turn, translates into more SRECs/year that I can sell. It's a modest difference, but it adds up over 15 years.

There is one minor flaw in your logic. You are assuming SREC will last that long.

[Naptown]

There is one minor flaw in your logic. You are assuming SREC will last that long.

Correct Maryland SREC's will run out in 13 years if not extended.
However the flaw in YOUR logic is you have discounted the savings due to added generation. SREC's or not I have seen an average of 5-7% increased harvest using the micro's above the PV Watts prediction which is used to certify his system.

[Sunking]

Correct Maryland SREC's will run out in 13 years if not extended.
However the flaw in YOUR logic is you have discounted the savings due to added generation. SREC's or not I have seen an average of 5-7% increased harvest using the micro's above the PV Watts prediction which is used to certify his system.

Rich I do not have any problems with microinverters. They have their place, but should not be used in every circumstance. I have no bias as I do not represent any manufacture or product, I am an electrical engineer who owns my own company, solar is just a niche we do and represents less than 4% of my business. It could go away tomorrow and would not affect me or be missed one bit.

But I know from experience SREC will go away, and even though they may be in the books for 13 years, don;t count on it, tax and rate payers are fed up with government waste and subsidies. Many states in the next few years will default, when and if it happens it is all gone and wiped off the books. All you have to do is look around at what is happening today.