how to compare inverters?

System

I’m going install 3KW panels on my roof. I see a lot of panel’s and inverter’s manufacturer and everyone promises me that his product is the best. I do not want to follow installator’s recommendations and want to see comparison test.
Would you recommend me a company who makes and publishes these test results ? Like Tom’s hardware does for PC market.
Google says nothing.

newenergy

Re: how to compare inverters?

Inverter manufacturers publish their own efficiency. The California Energy Commission publishes their own efficiency ratings.

http://www.gosolarcalifornia.ca.gov/equipment/inverter.php

Personally, I've installed a fair amount of SMAs, Fronius, and Xantrex. They are all good, but I had to replace a couple Fronius and one Xantrex and never SMA. All the replacements were paid under warranty and the manufacturer paid some for the labor of replacement as well.

SMAs are heavy as hell.

Supposedly Xantrex is easier to tinker with as far as software for monitoring goes, but you can get monitoring equipment with the others as well.

System2

Re: how to compare inverters?

thanks newenegry

wow, you replaced 2 of 3 invertes. I was sure that these middle-80th-technology boxes have to work 20 years minimum
I'm thinking about inphase but so scary coz they promised the life time over 100 years. I t sounds like "I was going to live forever, and so far all things are going well ))

newenergy

Re: how to compare inverters?

I've replaced a Fronius once and a Xantrex once, but I've installed several/many of them. The Xantrex was part of a recall, but it was working fine. I've installed far more SMAs than anything else.

arkieoscar

Re: how to compare inverters?

I have recommended, specified, installed Trace/Xantrex for many years. From DRs and SWs up to XWs now. I'm not happy with the way their quality and customer service has been trending. I'm having continuing problems with an XW system and they tried to ignore me for awhile and now finally have stayed on the case to try to get it resolved. I did a couple of small UPS systems and used the HF1800 inverter chargers and had to replace one twice. Now they are going to replace it with a Marine 2000 unit. It looks like an old DR. I hope it's as stout as they were but we'll just have to try it and see. BTW- They acted offended when I said they should pay some of my labor.

newenergy

Re: how to compare inverters?

Fronius definitely had no problem paying for labor. They just sent Two hundred something for replacing an inverter (4100W I think). Tech support was very good when I was running through the inverter tests before they decided it needed to be replaced.

I haven't had to replace an SMA, but twice I've had to call tech support and they were quick and helpful. (Once was about bypassing the string combiner and another was on a 3 phase system that needed something changed which wasn't mentioned in the manual).

System2

Re: how to compare inverters?

Finally I've bought Sanyo panels. wow... I've got good references, read several articles, and called four installers. Done !!!!.

But, in regard inverters...
I visited warehouses, touched inverters, tortured sales guys )))But still have not decided.

I've found the following boys ( 3KW. grid connected) on the market.

Kaco
SMA 3.0 KW
Xantrex
OutBack
Solectria
..
Enphase (scarry)

Which one (or two) would you buy guys ? Please help.

icarus

Re: how to compare inverters?

I have a somewhat Rhetorical question? Why don't you trust your installers opinion? Isn't he the one that is going to stand behind his work and his products? Doesn't he have (some) real world experience in your part of the world with installations/hardware/reliability?

It just seems that if you trust your installer enough to do a bunch of work on your house it might be wise to at least consult his opinion, and if you disagree, figure out why.

Tony

PS Why did you choose the Sanyos? Did the installer recommend them?

a0128958

Re: how to compare inverters?

With the exception of Outback, the remaining inverters you note are all compared in an Oct./Nov. 2009 article in Home Power magazine ("Grid-Tied Inverter Buyer's Guide").

My guess is Outback wasn't included in the article because Outback may not offer grid-tie-only inverters, which was the focus of the artcle.

Hope this helps.

Best regards,

Bill

System2

Re: how to compare inverters?

icarus wrote: »

I have a somewhat Rhetorical question? Why don't you trust your installers opinion? ..

I do, but.
Installers are businessman. They want $$$ and do not want any problems. That's it. Nothing else.
Sometimes they have relationship with a particular vendor and push his product only. Even If they have several vendors they suggest more profitable product. It is ok, it is just business-- but my profit is a little different than installers one.
I'm trying to buy a system for 20 years. It is not a car even , it is almost a home.

So I trust them, but I trust you guys more.

icarus

Re: how to compare inverters?

I am not arguing the logic of due diligence and getting other opinions. It would seem to me that part of that same due diligence is to do it for the installer as well. You did say, that the dealers don't want problems. (f they expect to be around a while).

I suspect that as a percentage, the dealer profit on Brand X or Brand Y is probably insignificant in the net/net. I personally would go with a brand (all other issues being essentially the same) that the dealer has the most experience with, has the best relationship with, so in the event of warrantee service he might have an easier time.

For example, how best would a situation resolve if the inverter fails near the end of the warrantee? Would the dealer who sells and installs Brand X for 99% of his installs have a better result than trying to get warrantee service on the 1 Brand Y he sold?

I'm not suggesting any particular course of action, merely pointing out that there are other issues out there that would matter to me.

BB.

Re: how to compare inverters?

Probably start with the $$$/Watt price installed. Then look at secondary issues that would guide you one way or another.

Other than Outback (which may not have a pure GT inverter at this time)--I am not sure that any of those you are looking at are a bad choice.

So, looking at other issues... Business stability/backing is good for warranty repairs--but in this current climate--who knows how long anybody will be around.

Next, I would look at the Voc/Vmp operating range and string sizing. See if the numbers that end up being suggested for your system have alternate sources. For example, the Xantrex units tend to have the widest operation range of ~200-600 VDC. You may find some 150-400 volt, and others at 250-800 volts (sort of making numbers up). If 10 +/- 5 years down the road, you need a replacement GT inverter, sizing your strings to the "generic" sweet spot of 240-450 VDC or so can give you easier options for replacement down the road.

Regarding Enphase--at this point they don't seem to have a viable second source--perhaps later they will (I have a relative that is working on the silicon for these types of per panel inverter systems with power line communications).

But--in the Enphase case, you could be left with 19 panels with Enphase in 15 years, and one panel with either no replacement available, or one that that is not compatible with the Enphase network monitoring system. Then watt? (what--a joke. A bad joke ).

Lastly, what kind of monitoring do you want to do. Some have pretty open standards that let you run your own PC/server. Others you have to purchase cards and software. And others yet you have to purchase the local hub and pay for a yearly website subscription to access all of your own data (Enphase).

Personally, I am not that much into monitoring. I try to just write down the kWhr per day running total and throw that into and Excel spread sheet once in a while to monitor the performance of the system (see if anything is failing). I did not want to spend the money/waste the extra energy on monitoring (a used laptop can eat 0.5 kWhr per day of my average 13 kWhr per day generation--a pencil works fine for me.

At this point, I am not a big fan of per panel inverters (I am not convinced that they can meet the life of the panels, and they may not be easy to access/replace/no alternate sourcing). But, if Enphase wants to sell into large system markets--there is a good chance that they are working with another vendor for plug compatible alternate sourcing and/or alternate manufacturing (just a guess--I have no information from Enphase or anyone else). No large system engineer is going to sole source major components from a start-up for a 20-40 year system (at least if he/she want to keep their job).

-Bill