How To Choose A Good Solar Inverter

How do you choose a good solar inverter? It’s a really important question. If you choose a bad inverter, it may turn out to be noisy, inefficient and unreliable. If you have a look at the inverter reviews that are coming in to SQ, some inverters appear to have an awful failure rate. For example at the time of writing the Beijing Kinglong New Energy (KLNE) inverter reviews report 7 failures from 13 reviews! Ouch!

Here is my attempt to answer this important question. And I’ve provided a transcript of my rantings below the video.

Transcription:

Hi. I’m Finn Peacock. How to choose a good solar inverter? That is an absolutely critical question because I would argue that the solar inverter is the most critical component in your solar system.

Why? Well, one, all the power goes through it. So if the solar inverter goes down, then the solar system goes down. Another thing, because all the power goes through it, the efficiency f the solar inverter will directly affect the efficiency of the solar system as a whole. And thirdly, the solar inverter is the most likely component fail early in the solar system, even a good one. So it’s absolutely critical that you don’t skimp on these components and if you can afford to upgrade any components in the system before you buy then upgrade the inverter to a quality one. I really think it would be worth it over the next 20 years that you own the solar system.

Now, the two most critical factors when choosing a solar inverter are: Number 1, reliability and then number two, efficiency. I would even go so far as to say it’s worth taking a small hit on the efficiency if you have to to get a highly reliable inverter. Now of course you can get super efficient, super reliable inverters.  Some of the good SMA’s for a start, but you would pay more for those. So if you have to… If you are on a budget and need to make a trade off, take a small efficiency hit before you take a reliability hit on the inverter. You don’t want your inverter to fail, trust me.

Now the other big debate in the solar industry is Chinese inverters versus European inverters and you definitely get two camps here.  You get the guys who say, “Oh Chinese inverters are crap.”And then you get the guys that say, “No, Chinese inverters are actually better than the European ones.” Well, I personally think that the European inverters are a little bit better than the Chinese inverters. Just. China will probably catch up with Europe soon because the Chinese they learn fast. Five years ago, Chinese inverters were pretty crap. I wouldn’t get one. Today, 2012, I would be happy with a good Chinese inverter. Although if I would be spending my money, I would pay a little bit more and go a European. Just because they’ve been making them for longer you know, they have been in the business 25 to 30 years. They have ironed out most of the reliable issues in the modern inverter, those European guys have absolutely nailed it. So it’s a lower risk. I think it’s a slightly better quality inverter if you go for European one, but some Chinese ones are good.

Let’s talk about some brands, good European brands: there’s the big daddy of the inverters that’s SMA, giant German company, biggest manufacturer in the world. You can’t go wrong with the SMA inverter, generally. But they are the most expensive. Horses for courses right? Slightly cheaper and also out of Europe is, Power One Aurora, those guys are Italian and they make great inverters. The other European brand is, Xantrex. I think all of those inverters are now made in the Far East but they’ve got great quality control. And I’ve never seen a bad Xantrex.

Good Chinese brands: you’ve got three that stand out; pretty low risk you’ve got Samil Power, you’ve got Growatt (who have had a few reliability issues maybe 3 years ago but they seem to have fixed them.) And you’ve got Zeversolar making some really good inverters these days. There’s probably some of the good Chinese brands that I’m not across and if that’s the case, give us a “shout” let me know and I’ll add it them to the list. But you know, at the end of the day why go with the brand that’s unheard of and you can’t get third party information on it. There are plenty of good inverters just go with the good brand. It’s worth it trust me. Even if you have got to pay an extra couple of hundred dollars.

The one thing you should know is this: get a 10 year warranty on your inverter, that’s critical. The standard warranty is 5 years. You can usually get a 10 year warranty if you push for it or you pay an extra hundred dollars or so.  It’s worth it. Like I’ve said, if anything will fail in your solar system, if it’s a well installed solar system, it will be the inverter. It is just the nature of the beast.

Finally, let’s talk about inverter sizing. Don’t get an oversized inverter.  It’s a waste of time and a waste of money. Unless, you’re going to expand your solar system in the next 12 months, you are probably just gonna spend more money than you have to. There are companies out there selling 5 kilowatt inverters with 1.5 kilowatts of solar panels. They say, “Oh you can upgrade your system in the future”. Yeah, but if you upgrade your system in 3 years, the chances of you still being able to buy the same solar panel are almost none. Why? Because the technology is changing so fast. I’m getting calls from people who bought their system 2 years ago, big inverter, back then 165 watt solar panels were the go. Try and find a 165 watt solar panel in 2012. Good luck, If you do find them, you would pay a fortune for them. So they are really struggling to upgrade the solar system. It’s working out cheaper to just get a new solar system. So don’t get an oversized inverter, it’s just a marketing ploy. Don’t do it.

It is actually okay to get a smaller inverter than your panel array and not a lot of people know this. You can, it’s in the standards, it’s in the guidelines. You can oversize your panel array to your inverter by up to 15% and that’s because you get inherent losses in the solar panels which means that you’re unlikely to ever get more than 80% of the rated power out of your solar panel array. So basically what I’m saying is, for example, if you’ve got 2 kilowatts of panels and the installer specifies a 1.8 kilowatt inverter. Don’t stress; he’s not ripping you off, it’s just kinda good, efficient design. The inverter in that case is 10% smaller than the panel array which is well within the safety margin of 15%. And it’s just a good economical way to size your system and you are not gonna be losing out.

So that’s everything I think you need to know about inverters to make an informed decision on your solar system. The inverter is absolutely critical. Please don’t skimp on the quality. If you can afford a few extra hundred dollars, upgrade the inverter, upgrade the inverter warranty. Many Chinese inverters are fine. If you can afford it, European inverters there’s a probably a little lower risk. Efficiency is very important and reliability is more important. So good luck buying your solar system, don’t skimp on the quality of the inverter.

About Finn Peacock

I'm a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and founder of SolarQuotes.com.au. My last "real job" was working for the CSIRO in their renewable energy division.

Comments

  1. Really??

    Xantrex went out of business 2 years ago!!! Company products were sold to Schneider Electric which since then already did 2 full product recalls…

    • Hi John,

      Schneider Electric are a top quality manufacturer. I have personally installed their control gear in Nuclear power stations. Only responsible manufacturers do voluntary recalls. Mercedes, BMW, and Volvo have all recalled cars recently. Would you say they are low quality manufacturers?

      Cheers,
      Finn

  2. Finn,

    This was an excellent read for me, as I seem to be in the inverter market. I had a grid tied PV system installed in 2005 at my home in California and have loved it. Except for the fact that one of my inverters, the Sunny Boy SB6000U, has began to fail. It is “derating” because of a heat issue which seems to be an issue with the fans. After contacting SMA, they offered me a newer one with a ten year warranty and said that they don’t service this model any longer. Are these just a disposable product? Why doesn’t anyone talk about repair of these units? I’ve searched on the internet and can purchase new fans for the unit and may look into having it repaired, but not sure if it’s the right thing to do. I was also concerned about getting another SMA product after this one failed in just 7 years time. Seems like a short life span to me, but I’m no electrical/solar scholar. Just a guy who thought that this PV system was a good investment and didn’t realize the the weakest link in the entire system is an expensive inverter!

    thanks for all your good info,

    Bill

  3. Walter Coruzzi says

    I am looking for a quality inverter as the chinese one failed after only 2 years . I have 11 panels installed above a 2 story pitched roof. I wish to buy to buy another inverter and require this to be fitted.
    Who can I trust this time

  4. John Thwaite says

    I agree with that argument Finn. I work for a medical device company – the largest in the world – and we annouce possible product alerts and recalls way sooner than any of our competitors do. The market trusts us more than the other guys because of it.

    I’m going through the initial self-education phase about solar power right now and I really appreciate your candid discussion of the key points. Thank you.

  5. I have two Sharp inverters 1.6 K.W. split with 12 panels. I thought it was a good idea at the time that the installer quoted for the system because if one inverter fails you are still generating with the other. As luck would have it one failed almost in week 2. I never noticed nor did I know what fault codes were. When I finally woke up it took a couple of weeks for them to come and find that they couldn’t fix it on site and now it’s another 2 weeks and sharp seem in no hurry to repair and return it. All in all five and a half months of half the system not working from virtually day one means it has been a very expensive system. Fault code was relay open and then it threw an over voltage fault code.

  6. I am looking to buy a system for my house. I am a radio ham and worry about RF noise from the inverter? I am trying to find out if I am best to go with pannels with inverters built onto each or one inverter to control all. Any pointers please ?

  7. Hi Finn

    I’d Green Engineering salesman come to my house and quoted me $6700.00 5kw on JinkoSolar panels 250watt each JKM265P-60-A with a SMA dual tract inverter (note that I have not even been told in details what SMA I would get). He has told me that Jinko is an American product. I signed up my contract on the day 13/12/14 as the guy said if I hold it until next week the price won’t be the same as the government subsidy scheme will be finished by 20/12/14 the price he has offered will not be the same! I have found out (from Eco Relief) that Jinko is not an American product and that the government subsidy scheme is still going. I was so disappointed with the salesman. I called this guy back, and he is still denying: he keeps saying Jinko is an American product. My question is should I still go for JinkoSolar system? and the SMA Sunny Boy 3800 is a way to go for 5kw solar system? Can you please help to give me some advice. Many thanks.

    • Jinko are a Chinese company. The solar rebate is not scheduled to finish on the 20th December. The rebate may change when the government decides what it is going to do with it’s RET review, but no-one knows what the outcome will be.

      Jinko are good panels. SMA is a good inverter. But if you are worried that the salesman has given you false information, you should probably go with an alternative company?

  8. Potential Energy says

    You highly rate SMA. I had a Sunny Boy 3800 installed in late Oct 2010. It went defective at the end of June and reading levels have halved. SMA don’t want to know and a repair, providing 1yr warranty, and transport costs come to as much as a new Samil with a 5yr guarantee. The proverbial 2 fingers is my view of SMA..

  9. Evelyn Rees says

    Thanks Robert,

    I have had my solar panels for five years now. I have a Sharp1600HD inverter. I did read your review on them and you said they were 95% efficient which was good to know. Four of my panels are facing north and four panels are facing east because of restrictions on my roof. So i have lost 15-20% efficiency on those. If i remember correctly they are German made panels so are highly efficient.

    If i have to get a new inverter which would you recommend and what size.
    The info you’ve given me and others is absolutely fantastic, thank you. Eve

    • Ronald Brakels says

      Evelyn, Ronald here. It sounds like you might be losing a bit of generation from your panels as the Sharp 1600HD inverter can only properly handle a single string and doesn’t handle having two sets of panels facing different directions very well.

      While I don’t know the capacity of your panels, with only 8 it is likely to be 2 kilowatts or less, so a 1.5 kilowatt inverter should be fine. If you want a high quality brand you can get an SMA or Fronius. But you could get a reasonable budget inverter for perhaps half the price.

      One thing you may want to consider if and when you replace your inverter is using microinverters instead of a string inverter, as they can make placing panels on a difficult roof much easier. At the moment this will cost considerably more than a string inverter, but microinverters are coming down in price.

  10. Finn
    You say dont get an over sized inverter but is cost the only reason for this? I am getting a 3.9Kw system installed and they are providing a 5Kw inverter as they say the company does not make 3.6 anymore.
    Thanks

    • Ronald Brakels says

      Hello Olfella, Ronald here.

      It usually pretty easy to check online if a claim that a company is no longer producing smaller inverters is true. Provided they have an Australian office you can also ring up the manufacturer and check.

      When an installer wants to put in a larger inverter than is necessary it is often because they got a good deal on a bulk buy of the most popular sized inverter.

  11. hi finn looking at investing in a new solar system, had received several quotes one is listing a solis 6kw inverter. can you please give me your opinion on the solis brand

    regards

    bruce

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