Cheapo Inverters vs. Expensive Ones

[eric@psmnv]

I know the old saying, you get what you pay for. Often that's true but sometimes it isn't. Sometimes all you get for your extra money is a name.

I'm brand new to all this stuff, so have mercy. I went looking for off-grid kits and found several featuring a Magnum MS4448PAE 4400 W 48 VDC pure sine wave inverter at a cost of around $2200. I've found a number of vendors selling seemingly equivalent inverters (same specs, at least) for $500-700, such as this one...

http://www.dhgate.com/product/12v-24v-48v-5000w-5kw-cheap-price-pure-sine/183300617.html#s1-0-1a|3060163214

Would a cheapo inverter like this work for those of us who must cut every conceivable corner to build something on a shoestring budget? Heck, I could buy two of them and just keep one as a standby and still save $1000.

What am I missing here?

[jflorey2]

What am I missing here?

Well, one obvious thing is that the inverter can't possibly work at those power levels. 10,000 watts/12 volts at 90% efficiency is 925 amps. There is no way the terminals on that inverter - or even the internal wiring - will handle that current. Even at 5000 watts you are at 462 amps, which nothing sane will handle.

What you will likely get is an inverter that will give you about a thousand watts of modified sine wave power - if your battery can support it.

Would a cheapo inverter like this work for those of us who must cut every conceivable corner to build something on a shoestring budget?

If you are really looking for a "cheapo" inverter, try something like a Prosine 1800. It will give you 1800 watts (for real) of real sine wave and you can pick one up for about $300 used on Ebay.

[lkruper]

I know the old saying, you get what you pay for. Often that's true but sometimes it isn't. Sometimes all you get for your extra money is a name.

I'm brand new to all this stuff, so have mercy. I went looking for off-grid kits and found several featuring a Magnum MS4448PAE 4400 W 48 VDC pure sine wave inverter at a cost of around $2200. I've found a number of vendors selling seemingly equivalent inverters (same specs, at least) for $500-700, such as this one...

http://www.dhgate.com/product/12v-24v-48v-5000w-5kw-cheap-price-pure-sine/183300617.html#s1-0-1a|3060163214

Would a cheapo inverter like this work for those of us who must cut every conceivable corner to build something on a shoestring budget? Heck, I could buy two of them and just keep one as a standby and still save $1000.

What am I missing here?

Where is the UL rating? 5000w / 48v = 104 amps is a fire waiting to happen. Also the warranty is only 1 year.

Also, I don't like their terms:

We provide 1 year warranty. If the item is defective, please notify us within 3 days of delivery.
All items must be returned in their original condition, in order to qualify for a refund or exchange of goods.
But shipping fee and insurance is not refundable.
Items returned after 7 days of delivery are only eligible for repair.
The buyer is responsible for all shipping costs incurred.

You can make sure the item is ok in just three days? And after 7 it cannot be replaced? And you have to pay shipping?

The web site is amateurish and contains grammatical errors.

[inetdog]

Where is the UL rating? 5000w / 48v = 104 amps is a fire waiting to happen. Also the warranty is only 1 year.

UL listing (not approval, not rating, not "built to UL standards") is absent. It cost enough that if they have it they will display it!

Note that CE rating, being a self-certification by the manufacturer with no independent testing, is only as good as the honesty and competence (one without the other is no good either) of the company. In this case that seems to be zero.

[lkruper]

UL listing (not approval, not rating, not "built to UL standards") is absent. It cost enough that if they have it they will display it!

Note that CE rating, being a self-certification by the manufacturer with no independent testing, is only as good as the honesty and competence (one without the other is no good either) of the company. In this case that seems to be zero.

Thanks for the reminder. UL lists devices, they don't rate them, correct?

[PNjunction]

Would a cheapo inverter like this work for those of us who must cut every conceivable corner to build something on a shoestring budget?

That only makes you a target / sucker for junk, and solar is not really for you. To do it right, you don't cut every conceivable corner, or else you end up buying things twice or more, or replacing with quality you should have done in the first place. Penny wise / pound foolish.

[inetdog]

Thanks for the reminder. UL lists devices, they don't rate them, correct?

Yup.

The also "recognize" components that can be used inside a device which will in turn be tested to some UL standard.
The recognized component mark is the backwards RU.
And it means nothing for the consumer or average electrician who cannot assert any kind of UL listing for an assembly that contains RU components just based on the RU mark.

[eric@psmnv]

5000w / 48v = 104 amps is a fire waiting to happen.

In that case, it's also a fire waiting to happen for these guys...

http://www.wholesalesolar.com

...because a lot of their off-grid kits are built around the Magnum inverter previously mentioned with the same specs.

The web site is amateurish and contains grammatical errors.

I knew I was taking a risk of confusing the question by using that particular product as an example. You're right, that one looks shady. I wish I had used a different example. However, as I mentioned originally, a lot of vendors sell inverters with the same specs in the $500-700 price range.

I probably didn't ask my question quite right. Issues of warranties aside, all I want to know is, electrically speaking, is there any reason why a cheapo inverter in the $600 range would not do the same job as the expensive $2200 inverters sold by wholesalesolar.com?

[eric@psmnv]

Here's a better example.

http://www.alibaba.com/product-detail/original-manufacture-5000w-12v-24v-48v_447508088.html?spm=a2700.7724857.35.1.uhv2wj&s=p

Why would an inverter like this not work just as well as a $2K inverter from Magnum?

[lkruper]

Here's a better example.

http://www.alibaba.com/product-detail/original-manufacture-5000w-12v-24v-48v_447508088.html?spm=a2700.7724857.35.1.uhv2wj&s=p

Why would an inverter like this not work just as well as a $2K inverter from Magnum?

It has all the same problems as the other example. No UL listing, no proof of worthiness or safety. The web site and product must meet the burden of proof, not the other way around. You should be asking the question, how does this site prove the product is acceptable and not assume it is unless it can be proven otherwise. What do you expect from a sales web site, that it give accurate and dependable reviews and information?

[eric@psmnv]

It has all the same problems as the other example. No UL listing, no proof of worthiness or safety. The web site and product must meet the burden of proof, not the other way around. You should be asking the question, how does this site prove the product is acceptable and not assume it is unless it can be proven otherwise. What do you expect from a sales web site, that it give accurate and dependable reviews and information?

Did you scroll down to the certifications section? There's a lot of information on the page. Overall, it looks pretty legitimate. Is UL listing the only way that you check a product's worthiness or safety? That said, suppose for the sake of my original question that I eventually find one that has the UL mark in the same price range. The real question is, is there any reason to think that a $700 inverter would not do the same job as a $2200 Magnum inverter?

[lkruper]

Did you scroll down to the certifications section? There's a lot of information on the page. Overall, it looks pretty legitimate. Is UL listing the only way that you check a product's worthiness or safety? That said, suppose for the sake of my original question that I eventually find one that has the UL mark in the same price range. The real question is, is there any reason to think that a $700 inverter would not do the same job as a $2200 Magnum inverter?

When I pulled up certs I did not see anything. And yes, if the unit is to be used in the USA, then UL listing is important, if not critical when installed in a residence where my family lives. Would it do the same job? Like I said, THEY bear the burden of proof, a burden I have not seen met.

So, whether or not I give you a reason, it is irrelevant. I do not have the burden of proof, the manufacturer does. And I see none.

[jflorey2]

Here's a better example. http://www.alibaba.com/product-detai...5.1.uhv2wj&s=p Why would an inverter like this not work just as well as a $2K inverter from Magnum?

Same problem. It is available in a 12V version that they claim goes to 10,000 watts surge. 10,000 watts/12 volts at 90% efficiency is 925 amps. Those terminals (and likely the guts of the inverter) cannot handle almost 1000 amps without a (probably spectacular) failure.

That means they are lying. What else are they lying about?

Did you scroll down to the certifications section?

Yep. Think they are telling the truth? For example, do you think for IEC 60950-1 testing, they told the test lab to test at 5000/10,000 watts? Or did they perhaps told the test lab "this is rated for 1000 watts" when they submitted it, to ensure it passes?

I think everyone goes through a phase like this when they get involved with alternative energy. "Hey, I found instructions that let me build a solar panel for pennies!" "I could take this old alternator and build a super-efficient wind turbine that will work in low winds." "Look how cheap this inverter/charge controller is!" Then you make those mistakes a few times and learn. It may be that you have to make the same mistakes. Since this is a fairly inexpensive inverter ($395) it will be a cheap lesson.

[eric@psmnv]

Same problem. It is available in a 12V version that they claim goes to 10,000 watts surge. 10,000 watts/12 volts at 90% efficiency is 925 amps. Those terminals (and likely the guts of the inverter) cannot handle almost 1000 amps without a (probably spectacular) failure.

That means they are lying. What else are they lying about?


Yep. Think they are telling the truth? For example, do you think for IEC 60950-1 testing, they told the test lab to test at 5000/10,000 watts? Or did they perhaps told the test lab "this is rated for 1000 watts" when they submitted it, to ensure it passes?

I think everyone goes through a phase like this when they get involved with alternative energy. "Hey, I found instructions that let me build a solar panel for pennies!" "I could take this old alternator and build a super-efficient wind turbine that will work in low winds." "Look how cheap this inverter/charge controller is!" Then you make those mistakes a few times and learn. It may be that you have to make the same mistakes. Since this is a fairly inexpensive inverter ($395) it will be a cheap lesson.

I hear you, and I am certainly in that phase right now, but I do not give up easily. Here's a page that lists about a zillion similar products.

http://www.alibaba.com/showroom/5000w-power-inverter-48v-pure-sine-wave_3.html

I have a hard time believing that all these products are out there causing fires in homes all over the place.

[lkruper]

I hear you, and I am certainly in that phase right now, but I do not give up easily. Here's a page that lists about a zillion similar products.

http://www.alibaba.com/showroom/5000w-power-inverter-48v-pure-sine-wave_3.html

I have a hard time believing that all these products are out there causing fires in homes all over the place.

I am done following links. None of them meet the burden of proof. From the link itself I can see that it is a 5000w inverter which will not be safe (ie > 100 amps) even at 48 volts. Without a UL listing I would not touch it.