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SMA Sunny Boy 240 micro inverter, what the?! April 4, 2014

Posted by Maury Markowitz in solar.
Tags: ,
Image of the SunnyBoy 240 micro inverter, all bright red and shiny.


The SMA Sunny Boy 240 micro is finally starting to appear in numbers at all the online stores, which is my definition of “real”. So now that we have some concrete numbers to work with, it’s time to write up a quick overview/review of the product.

And all I can say is “what the hell?” This thing’s been in development for years, and they still managed to release a product that is so obviously flawed that it would be a hard sell even if it wasn’t the most expensive product on the market.

And it is. The most expensive.

Well, at least it looks nice.

A long time ago…

Image of the interior of the SB240, showing that it uses electrolytic capacitors

See the brown thing on the right? Electrocap. In the SB240.

First a quick review.

Of all the micros that have come and gone over the years, it was Enphase that first hit the sweet spot of price and power that made it a practical system.

At first they were pooh-poohed by the “big guys”, including SMA, but as Enphase turned from one success to another the complaints grew more strident. In particular, everyone started complaining about the electrolytic capacitors in them, and how there was no way they were going to last.

But with the sales continuing to climb, it wasn’t long before the string inverter companies were seeing real effects on their bottom line. And then came their versions of the micro. Of the many micros released since, its the PowerOne and SMA models that are most interesting from an overall market perspective. These are the big guns.

When SMA announced the SB240 way back when, they were the big dog in the market. Now in 2014? Not so much. Nevertheless, I think it’s safe to say the SB240 was one of the most anticipated products in years. Everyone’s perfectly happy with SMA’s kit, and their reliability is legendary. So if they were going to do a micro, you know they’d stand behind it.

Sunny Boy to the rescue?

I have no reason to doubt that the SB240 is as high quality as any other SMA product. But if you want to have any effect on the market, you need to actually sell it. And that’s where I’m mighty sceptical of the SB240.

You see, the SB is, by far, the most expensive micro on the market. Real prices differ from the web considerably, but you can still get a good feel for the relative cost of the products with high accuracy by comparing prices on a single site. So let’s do that…

Store                      SB240     M250
WholesaleSolar    $190.00   $166.00
EcoDirect            $190.80   $164.00
CivicSolar            $203.52   $184.00

It’s like this everywhere, the SMA is clearly more expensive than the M250, by about 10 to 15%, across the board.

Now if that were all there was to it, we could end the debate right here. You could make a decision on whether or not the price is worth it, considering the SMA has a 30 year warrantee and might actually be good for that.

But that’s not all there is to it.


Image of the SB240 monitoring system in its bare form, normally one has to pay extra for the box

What, you want a box with that? $ure thing!

So then we come to the Sunny Multigate. The Multigate is the communications system for the SM240, like the Envoy is the communications system for Enphase. But there’s a couple of important differences.

For one, the Multigate runs the power cabling through it. This is in stark contrast to the Envoy, or anyone else for that matter, where the comms system plugs into any nearby power receptacle. As you might imagine, this makes the Multigate somewhat more complex than other products.

It also means you’re back to a single point of failure, if this thing stops working, your array is down. That’s not a good design! Micros were invented precisely to avoid this problem.

Since the wiring from the inverters has to run through the Multigate, that means that it has to be located wherever the panels are, or close to them anyway. So if your panels are on your garage, like mine, that means I need to run an ethernet cable over there.

That’s right, Ethernet. No Wi-Fi. In the 21st century. *sigh*

And then to add insult to injury, this SMA video boasts that they don’t use unreliable powerline communications, that they have Ethernet all the way. Except for that fact that the inverters are using powerline communications to talk to the Multigate. This sort of spin is only making matters worse.

Now the good news, if you can call it that, is that the product isn’t all that expensive. A version in a box, which you might want considering there’s bare 240V wiring exposed on the top where things can fall on it, lists for between $400 and $600, comparable to the (dramatically overpriced, IMHO) Envoy.

But wait, there’s more. You see, the Multigate can only communicate with twelve inverters. That’s right, 12. So if you have a medium sized system, you’ll have to buy multiple Mutigates and wire them all together. You can buy add-on units for about $250, so let’s round it off and say that this system adds $25 to the price of every inverter. Compare this to the Envoy which supports 250 inverters and has Wi-Fi.

This baffles me. It appears that the Multigate also contains some of the electronics for the rooftop system, sort of like SolarEdge, but if that’s the case, none of the documentation is very clear on exactly what functions it performs. Long and short though, your system doesn’t work at all without one. This too is in stark contrast with, well, everyone else.

If that wasn’t enough, the included wiring is L1, L2 and ground. I’m not 100% sure, but I don’t believe that can be used in many locations, at least not if the power is running back into the house’s wiring or a pony panel. I think you need to have the neutral as well, but I’ll check into this.

No, stop, my ribs are aching!

Image of the SB240's cable that adapts from the micro to the panel connectors, which adds cost to an already expensive system

It just keeps adding up.

If you want to understand just how long this product has been in development, let’s consider one unique feature of the system, its panel connections. You see, the Sunny Boy doesn’t have any. Instead, it has a socket, and you have to buy an adaptor for your panel’s connectors.

Back in the late 2000s when the 240 started development, this actually solved a problem. Back then there were several connectors being used, MC4s, Tyco Solarloc and even some REC. But that war is long over, everyone uses MC4 now, Tyco even makes MC4 compatible junction boxes.

Why do I mention this? Well every connector you put on a box adds to the cost. In the case of the SMA240 they have both the MC4 connectors and this fancy plug-n-socket that you plug the cable into. Or they could have, like everyone else in the industry in the last five years, simply selected the MC4 and built those onto the box.

But they didn’t, so expect to pay at least another $10 on top of everything else.

If there’s anything good in all of this, it’s the cabling from inverter to inverter. In spite of having connectors on both ends, instead of one-per-inverter like the trunk solution, the price is comparable to the Enphase and PowerOne cables. The advantage here is that there’s no cutting and splicing of the cabling, which is a serious PITA with the others.

Wait, not quite

Did I say no cutting and splicing? Not so fast… while that’s true on the roof, there is one place where you do have to cut the cable, at the Multigate. Why is that worth mentioning? Well basically since each string of inverters has to plug into a Multigate, and the last connection on the string is one of these sockets. So for every string you have to buy a socket with wires coming out, and then splice those wires into your own runs to the Multigate.

Why is this even worth mentioning? Well in most places you, the end user, are free to assemble any wiring that has a “convenience socket”, but you’re generally not allowed to do wiring to the grid if there was any sort of assembly required. The socket used on the inverters is a convenience socket according to code.

So in other words, if the Multigate used a socket, you could do all the assembly right to the end of the system by yourself. You’d only need an electrician to do the very final step, the connection to the grid. So, yeah, this is actually kind of annoying.

So, in the end…

I don’t doubt for an instant that this is, technically, a great product. But the minor annoyances and cost adders make me think it’s a turkey. I know the solar market, and it’s cheap-ass. If one inverter is $1 more than the other, they’ll save that $1 every time.

So here we’re looking at:

$190 for the box
$25 for the Multigate
$25 for the cables (two sets)

Which brings you to $240 for a 240 Watt inverter, so $1 a Watt. This is in an era when 50 cents/W is considered widely expensive.

When I look at this, strange things happen in my brain. You see, when you talked to the SMA people about this product any time before it launched, two things would always happen. First they’d badmouth everyone else. But then they’d bad mount their own product. Every time, without fail, they’d try to tell you that the entire micro concept is crap.

Its like they wanted it to fail. In my more febrile moments I imagined internecine warfare among the cubicles in the German offices – nerf everywhere, shouts of “death before micro!” ringing out, delays all along the line…

And then its delayed for years, and launches like this. Could I actually be right? That’s a scary thought, but how else to explain it?


1. Richard - May 13, 2014

Nice explanation of this failing market introduction. You feel that SMA doesn’t really want to make and sell the product.

Maury Markowitz - May 13, 2014

They have brand recognition and a reputation for quality like no one else, but they’re just not capitalizing on that.

2. Kara Mirch - September 21, 2015

Unless SMA can see the wood for the trees, they will in due course fall by the wayside like many in this industry when technology overpowered the neanderthals.

Maury Markowitz - September 21, 2015

No sign that they have so far…

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