Not happy, Jan…….

8 04 2017

If you’ve been following this blog, you will know I’ve been saying for quite some time that out of the ludicrous Lithium battery rush happening right now as a ‘fix it’ for all and sundry energy problems, a lot of disappointed people will surface. Well, one just has, and he’s one of the most high profile person in the sustainability movement.

I met Michael Mobbs almost certainly before 2010, which is the year I went working for the solar industry. He gave a public lecture about sustainability in Pomona at the Rural Futures Network; I wonder how that’s going now..? Mobbs has undertaken converting an old terrace house in Sydney to ‘sustainability’ by disconnecting from the water grid and sewerage. He also went grid tied solar, the whole project is well documented on his website, and you have to give him credit for doing the almost impossible…. in Sydney no less. I for one would never undertake such a project, it’s so much easier to start from scratch in the country! And that’s hard enough, let me tell you….

It now appears, Mobbs decided to also cut himself off from the electricity grid…. and it seems that didn’t go so well….

mobbsbatteriesOn Mobbs’ website, there is an “invitation to install & supply an off-grid solar system” It seems he had one installed in March 2015, but it’s not working as it should, or at least as Mobbs thought it should…..

Firstly, let’s start with what he got……. It’s a bit hard to tell from the photo, apart from the fact it is an Alpha ‘box’. From the blog, I also established that this comes with a 3kW inverter, itself a problem, it appears to be too small. Going to Alpha’s website, I cannot find the system Mobbs appears so proud of in the above photo; and let’s face it, two years is a long time in the world of technology. All the products on display say that the output of these cabinets is 5kW, but nowhere does it say it even features an inverter.  Solarchoice’s website shows a 3kW Storion-S3 cabinet, but not even it looks like what Mobbs has in the photo – it only has one door, the ‘new ones’ have two….. The inverter is called an AEV-3048, and perhaps the A stands for Alpha, and 3048 means 3000W/48V, but it’s all guesswork because finding information is a problem.

So why is a 3kW inverter a problem in a house with a claimed baseload of 86W, very close to what we achieved in Cooran actually…..

Another huge flaw with the Alpha system that I’ve recently become aware of also stems from the fact that all the energy first goes through the batteries: the Alpha system’s output is always limited to 3,000W regardless of the solar size; it can’t deliver above this. This is an extremely important point to understand because it affects the way I live and how I’m able to use my appliances. I’ll break it down in a way that’s practical and simple; prepare yourself to be blown away by this outrageous system limitation.

We’ve already established that the base load of my house is 86W. Let’s say I wake up in the morning, turn on a couple of lights in the kitchen because it’s still dark (20W), turn on the toaster because I’m in the mood for toast with butter for breakfast (1,200W), and my daughter (who happens to be staying with me) turns on her hair dryer while getting ready (1,500W) and she decides she needs to put on a load of laundry before she leaves the house (500W). Doesn’t seem too out of the ordinary, right? Well, we would be in trouble: all of the power would cut off, and the Alpha system would shut down because we would have exceeded its 3,000W limit. Regardless of the size of my solar system, I can NEVER exceed 3,000W of power consumption in my house while using the Alpha system. This was very hard to swallow.

Oh Michael…….  welcome to living off the grid!

Mobbs gives a brief description of how he worked out this baseload….

Step one, determining my total base load, wasn’t as easy as I expected, especially given the fact that I have three different monitoring systems that could provide me with the information. The Efergy and Wattwatchers systems confirmed what I already knew: my house’s base load was about 86W (60W for the aerator and roughly 20W for the fridge occasionally turning on).However, where I ran into problems was with the Alpha ESS reporting system: it was saying my base load was 257W, which is three times larger than the base load reported for the house.At first I thought this difference of 171W was the base load of the Alpha system itself, but their numbers just didn’t add up.

I do have a theory here, he may have got the sums wrong because he used to be grid tied, and maybe, just maybe, his figures did not include what was exported. But I’m only guessing. My main reason for thinking this is that he is running a conventional fridge, while we achieved our low baseload using a freedge which consumes 20% of the energy a conventional fridge does…. make no mistake, a conventional fridge’s ‘baseload’ is half or more of his 86W. He’s claiming 20W for his fridge (480Wh/day, 20W x 24 hrs), but I have never seen any fridge perform that well…. Most fridges today still consume a whole kilowatthour a day. So there could be another error there.

But it gets worse……

Now you see why I said that I probably made a huge mistake by purchasing the Alpha system when going off-grid. The simple truth is that the Alpha system is not designed to be used in an off-grid setting, and they have not implemented the necessary retrofits to make it work in that environment. However, during my recent research, I came across a product that is designed specifically to be used off-grid and shows great promise for high efficiency and effective energy management: the SMA Sunny Island system.

Bad news Michael……  the SMA Sunny Island is not designed for off the grid either, it’s made to work with other SMA grid tied units in a hybrid grid/backup batteries system.

Worse still, he also seems to have storage issues….

For the last few weeks, in the particularly cloudy and rainy weather Sydney has had to endure, Mobbs had to turn off his fridge (bloody fridges, they are a curse…) during the day to ensure that the house, which he shares with two others, has enough power for a “civilised life” at night-time. Worse than that, the system has a bug in it that causes it to trip out every couple of days. It seems flashing digital lights have become part of his life….!

“I’m running short of power,” Mobbs said complaining that the system that he has in place is delivering 1kWh/day less than he expected. “I thought this would be a walk in the park, but I appear to have tripped over.”

I’m seriously starting to think a lot of installers have no idea what they are doing. I recently related the story of my friend Bruce whose inlaws replaced a perfectly good system (because of a fridge no less!), and they were sold a Sunny Island, with I was told over the phone just two days ago, gel cells for storage……… completely not what either Bruce or I would have bought. Solar companies (including this well known one who shall remain nameless) have simply turned into salespeople selling whatever it is they have in stock off catalogues…….

Mobbs then writes……

The main difference between the Alpha and Sunny Island system: Sunny Island can send solar energy directly to the house when it is needed and completely bypasses the system’s batteries. SMA’s Sunny Island system not only extends battery life by not cycling all loads through them, but using solar directly into loads means items can be set to run on timers during the day, (washing, dishwasher etc) to maximise the benefit of an abundant afternoon supply of solar. It also has a larger peak design capacity than Alpha. For example, if you have a 4kW solar system, with the SMA units that would allow a potential delivery of 4kW of solar (in optimum conditions) directly into the house’s load + the 4.6kW of power from the batteries delivered by the Sunny Island controller (they can run in parallel to each other).  That’s a big potential 8.6 kW of continuous capacity to loads.  As I’ve already pointed out, in contrast the Alpha output is always limited to the 3,000W delivery of the battery inverter regardless of the solar size.

More bad news Michael…… this only works that way if you are grid tied with a hybrid system!

Michael also doesn’t seem to understand how off the grid works…

Alpha has an inefficient way of managing my solar energy (by diverting all of it through my batteries first), which decreases my battery life by constantly charging and discharging them…

Errr…..  Michael, that’s how battery storage works! Which is of course exactly why Lithium batteries are not good at this. Mobbs also wrote…:

Like any system that transfers and converts energy from one form to another, there are going to be losses. No system is perfect. However, as I started doing more research, I became aware of a key element of the way the Alpha system operates that may mean my decision to purchase it was a huge mistake: the Alpha system transfers all its incoming solar energy through the batteries before it delivers it to the house. When I learned this, I was devastated. One of the most important figures of merit in a system such as mine are the battery losses. If you put 1kWh into a battery it doesn’t all come out! There are losses associated with both charging and discharging. The higher the charge/discharge rate, the greater proportion of energy is lost and the shorter my battery life becomes. So, I repeat, all my energy is getting charged and discharged through the batteries before I ever even see it in the house. For someone living off-grid, this level of energy loss and battery depreciation is unacceptable, and I was never made aware of it by the installer.

This is why I know there will be a lot of disappointed grid disconnectors. They have swallowed the idea that living off grid is just like living on it hook line and sinker, when it cannot possibly be. How long have I been saying solar has shortcomings?

If you’re going to go off the grid, first, you need to know exactly how much energy you’re consuming. Then you need to know what your peak power demand will be so you can size your inverter. Then, you must size your battery bank so that you can go on living through a series of cloudy days without your batteries falling over. Accurate climate data is really important. And if you ask me, any off the grid system should be tailor made for the household, not all fitted in a box…..

The comments on Mobbs’ blog are interesting, including one from Alpha who obviously can do without the bad publicity and are suggesting entering into consultation….. well if you ask me, the time for consultation is before installation, not after it’s established the gear does not perform as needed….

Furthermore, and this is most important, get batteries that can be flattened and recharged for as many times as you like, almost forever if you go the way of Nickel Iron batteries……

At least Mobbs is aware of what his system is doing, but most consumers don’t. They will buy these cabinets, not understand what the monitors tell them, and the Lithium batteries will be cycled to death, failing early without a doubt, driving incompetent solar companies broke and giving solar power a really bad name. Plus, let’s face it, by the time all these systems die, you won’t be able to get replacement bits in a post collapse world….

There is one more issue…… on his blog Mobbs shows..:

In 1996, I installed 18 solar panels, each with 120-watt capacity. It reduced the amount the house took from the grid by more than 60%. Since then, I have installed 12 additional panels, bringing my home’s total system capacity to just over 3.5kW. mobbs panels

In addition to the roof solar cells, the house uses sunlight to heat water through a standard solar hot-water system. The environmental savings achievable by using solar hot-water heaters are summed up by Gavin Gilchrist in his book, The Big Switch:
“If all the electric water heaters in Australia were replaced with solar ones, greenhouse gas emissions from Australia’s households would be cut by one-fifth.” One fifth is one mighty big saving!

The Bottom Line… I am saving hundreds of dollars every year not paying electricity bills by powering my household appliances using the Sun. 

I totally concur re the solar water heaters. Amazingly, I have friends in Geeveston who have one, and they hardly ever boost, which is astonishing considering how everyone was telling me how poorly solar would work in Tassie.

BUT…… all those original PVs were replaced when Mobbs cut the cord and increased his array size from 2kW to 5kW…… they were only ten years old, and as Prieto pointed out recently, the early retirement/replacement of PVs and balance of system can drive the ERoEI of solar to negative territory….. I can’t find mention of what happened to the obsolete 120W panels for which it might be hard to find compatible equipment.

One last thing……  his baseload of 86W is clearly wrong if a 3.5kW array can’t drive it. Our electricity habit was run for years on just 1.28kW, and I intend to now do it in Tassie with just 2kW. I rest my case.




18 responses

8 04 2017
8 04 2017

Hmmm pretty well agrees with what I’ve been saying. What I don’t understand though is this says he has a separate 5kW inverter, so why won’t it deliver more than 3?

8 04 2017

Would the output all have to go through the inbuilt inverter and would that be the limiting factor irrespective of the size of the external inverter?

8 04 2017

I doubt he has two inverters……. without Mobbs telling us exactly what he’s got, we’re only speculating, but I think he has a 3kW inverter myself…..

8 04 2017

So not only did he not research what was available or fully understand his needs, he maybe doesn’t even know what he purchased

8 04 2017
Doone Wyborn

A 3kW inverter will take a surge of 6kW, and run quite happily for a few minutes at 4.5kW so I don’t understand why there is a 3kW limit with the Alpha sustem.

8 04 2017
Nathan Surendran

But, but, Tesla!!

9 04 2017

In 2012, Progress Energy Florida offered to subsidize 66% of a grid tie 7.5 kw system on my home. After careful analysis I declined, electing to continue with conservation via solar assisted hot water, line dry laundry, and improved insulation. My last monthly electric bill was $47 (USD), and nothing I’ve read in the ensuing almost five years has caused me to regret that decision.

Thank you for this blog.

9 04 2017

You’re welcome…… but there are situations, like the one we had in our last house, where the feed in tariff can actually give you an income, which, when you live on the smell of an oily rag like we have been for the past twenty odd years means we could actually afford to pay our rates/land taxes!

9 04 2017

That would have been a deciding factor Mike, if Progress Energy paid retail rates to pv suppliers here as the Gainesville FL co-op does. Some guys were getting $200-$300 per month up there. Now, with Duke energy in control in my area, I’m afraid it’s hopeless. At least the deceptive ballot initiative was voted down, what a pack of jackals!

9 04 2017

“the SMA Sunny Island is not designed for off the grid either, it’s made to work with other SMA grid tied units in a hybrid grid/backup batteries system.”

Sorry to contradict Mike, but the Sunny Island *is* designed for off-grid. That’s the “Island” part. It provides an ac bus (‘grid’) for the normal grid-tied SMA inverters to work with.[1]

And, there’s more wrong with Mobbs’ understanding… there’s really no such thing as having to “go through” the batteries. There are only two terminals… So whether it’s an ac or dc bus, if there’s enough incoming energy to meet the instantaneous needs, then the batteries won’t be cycling. If there’s more (and they need it), they’ll charge, and if there’s less they’ll discharge.[2]

What kind of technical guy calls an inverter power output limit an “outrageous system limitation” and a “huge flaw”. Does he complain when his car doesn’t go “infinity kph” or when he can’t flush a swimming pool into his off-grid sewerage? 🙂

[2] Electrical engineer, worked in the industry

9 04 2017

I agree with the sunny island being for off grid and that most do not understand the concept of off grid.
The problem with the system Mobbs bought is it is fine for what it was designed for, but it is not an off grid system, it is a back up system or UPS.

I think he thought the inverter would power the house from the panel output and charge the batteries for use after dark, not cycle through the batteries which it is dong.
Pity, because most of what Michael has done to date is very good.

At least his discarded panels weren’t sent to the tip.
But I suspect he could have still used them, they would have been 12v not 24v, and with a little thought could have linked to become 24v/240w, similar to todays smaller main stream panels.

9 04 2017

OK, point taken….. I’ve only ever seen them as a ‘plug and play’ add on to turn grid tied SMA devices into hybrid systems…..

10 04 2017

It also occurred to me that likely SMA have actually changed the Island since I last saw one, which was now several years ago…. that link you supplied talks of “A NEW CLASS OF SUNNY ISLAND”, and the last one I saw wasn’t yellow either!

I’m pretty sure the original Island inverters were add ons to grid tied ones, and there are obviously not. I’ll have to edit my article……..

10 04 2017

I worked in the industry in 2008/9, and they were yellow then.
As far as I know, they’ve always been for off-grid applications (“Island”) and they’ve, as you said, always required grid-tied inverters. They just provide the “grid”, and the grid-tied inverters interface to panels and do the usual stuff – MPP tracking, protection, etc.

10 04 2017

I am pretty sure sunny island has always been an off grid unit, saw one off grid set up 15 years ago at a place I was buying some gear at.
One 3or5kw sunny island and three 1kw sunny boys, panels and batteries etc.
There has been about three versions, blue, red and now (?) a yellow one.
And yes they are basically plug & play, very dangerous if connected wrong.

Easy to be confused, most retailers don’t know what they are selling, and will spruke the latest company line/catalogue.
Which is a great pity as selling solar is different than selling lounge chairs, as we all know.

9 04 2017

Some people, eh?
We set up our small system for a small fridge and some lights, cost a lot even just for that. I was telling some typical townies only the other day that it is about the same money as being on grid and paying the bills. I bet they didn’t believe me!
It doesn’t get any more civilised than running a fridge. The hair dryer, toaster and tv are not necessary.

9 04 2017

To prove to SWMBO that we could go off grid I am setting up a trailer with panels, batteries inverter etc to run some of the house.
If she is still not happy then powered camping is the future.

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