Imeon 9.12

[Neb]

Hi Guys.

I've just purchased 30x 310w Canadian Solar PV modules, 4x Trojan 100Ah Vrla Agm Batteries and an Imeon 9.12 Smart inverter.

It's 9Kw DC input and 12kw AC 3 phase output

I'm planning on installing this on a north facing roof in Cape Town. (Renovating the house and installing this system as part of the renovations)

The house is a 4/5 bedroom but at the moment only 2 adults and a 5 year old will live in it

All lighting will be LED, there are 2x150l geysers that are heated by a solar water heater and heat pump.

There are obviously all the other appliances (washing machine, dishwasher, fridge) including a 1.5kw pool pump/chlorinator system that would run during Sunlight hours and a 750W well point pump Irrigation system that would run for an hour in the AM and PM.

I would also like to run energy efficient air cons if needed, but good insulation is first prize.

My worst case of usage recorded was 40KWh per day but with the efficient lighting and water heating it should be less.

I would like some expert opinion about the way the system has been sized and what I could run off it? My aim is to not use Eskom ever unless there's something wrong.

Would I need more batteries? Should I change the batteries to Lithium Ion?

I Look forward to a response.

Cheers Ben

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[Mike]

Hi Ben, welcome to the forum.

my opinion, your batteries are your weak link, to make it through the night with the majority of your home online, i would believe a minimum of 500ah battery bank. on a 100ah you could make it if the draw is no more than 300w per hour. the inverter is good giving you 3.4kw per phase but noisy. hopefully going in your garage as far as possible from lounge and bedrooms.

[Chris Hobson]

Hi Ben

Welcome to the forum.

Your system looks like it should carry your load. Your battery bank is to light for your system. You want to utilise the energy from panels during the day if possible. Your batteries are insufficient to carry overnight load. (Oh good Mike has replied I will go with his 500Ah. You must realise that batteries are the most expensive component of a solar system, the most easily damaged and has a finite lifespan (panels do too but we taking decades before you will need to replace them). You still will not have much more that a day's worth of energy stored in your batteries. If you have one of those Cape storms you will still need grid power. It is not worth spending too much on batteries (especially your first set) as the major advances to come will be in battery technology and in 5 years time current battery technology is set to be superceded. Lithium is very nice but tolerance to overcharging is minimal. 

[Neb]

Thanks Chris and Mike!

So what would be the easiest way to achieve 500Ah and 48V? Lower voltage batteries with higher Ah rating? More expensive?

Yes! All heavy loads like washing machines and pool pumps only work in the day,

the inverter is going in a DB room in the workshop. What do you guys think of those new Tesla Power Wall batteries, any good? Will update about how it's going when I've used my system for a while. I'm so excited about not using Eskom. Does the Imeon overcharge batteries? How do you prevent that? After reading about lithium Ion it seems like the wise decision long term?

Cheers Ben

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[Mike]

Tesla = 6.4kw and cannot be paralleled at this time, talk of a being able to parallel two by July. 2volt cells would be my choice if i had money lying around, at the moment i am using 12v 250ah gel type, they are working for me, panels during the day and battery at night - so far have not exceeded 30% of battery. No the Imeon will not overcharge the batteries, just have your installer calibrate them when installing.

[Mark]

Is the Windy Windy up yet Mike...

[Mike]

46 minutes ago, Mark said:

Is the Windy Windy up yet Mike...

nope, still awaiting the monopole's arrival

[___]

19 hours ago, Neb said:

4x Trojan 100Ah Vrla Agm Batteries

I agree with Mike here, this is the weak point. Capacity wise it is very close to my own. I have a 200Ah 24V bank. In both cases we have 200 * 24 = 100 * 48 = 4800Wh, which at 50% DoD means you have 2.4kwh to use at night. In my experience, it can be done, but then you must keep loads below 200W at night. Mine is more like 350W, and I don't even have all my lights on the inverter, I only have a few plug-circuits on the inverter. You need to at least double the battery capacity, and even that won't be good enough to go completely off-grid.

However, I don't think it's a good idea to go completely off-grid just yet. Battery storage is still more expensive for electricity below 600kwh, and is close to the same price for electricity above 600kwh (in Cape Town anyway), so another way to deal with this "problem" is to revise this part:

19 hours ago, Neb said:

My aim is to not use Eskom ever

Try not to use Eskom, or CoCT rather, for electricity above 600kwh. That means you can go with those batteries for now, and get something better in a few years.

There's more to your story that sounds like mine. I too started at 40kwh a day (now at 25, 35 in winter). I just have way less panels. I have just enough panels to recharge my batteries every day :-)

[___]

3 minutes ago, plonkster said:

Try not to use Eskom, or CoCT rather, for electricity above 600kwh

... and so it begins. As time goes by, more and more middle-class people all cut their consumption to no more than 600kwh a month. <insert evil laugh>.

[Neb]

Thanks Plonkster.

I will consider the option of doubling my battery bank, I'm trying to employ a system that can comfortably sustain the house in an off-grid situation. It should handle the loads regardless of the weather and season (that's why I've gone for so many panels and a 9.12 Imeon Energy) the system should be capable of powering the house during the day without much help from batteries but I agree with you guys that the batteries would struggle, especially on long winter nights.

I want a bank that would be perfectly suited to my application, i don't mind investing in a battery bank that could last 8+ years because electricity is not going to get cheaper.

So for my application considering 50% DOD, what arrangement of batteries would work without problems?

On a sidebar, would it make sense to have freestanding aircon (heat pump) 1500W with temperature programmed at 20degrees Celsius in the DB room to keep the bank and inverter cool on hot days? I thought it should work because the Imeon should supply direct power from the panels therefore not creating a wasted energy cycle? (Eg. running the cooling system to cool batteries off the said batteries makes no sense) any thoughts?

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[Guest]

Neb, a thought from the sideline.

Their is a learning curve involved before one 'understands' what it means to become Eskom. 

Inverter and panels are fine, they last, the batteries are the weak point. 

It could be an idea to buy a cheaper bank, learning with them, before you go big.

[Neb]

I got you there TTT, I wouldn't feel very good marching a bank of Trojans to an early death[emoji106]

Any suggestions on a good cheaper brand that could do the job?

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[Guest]

Not sure, but two thoughts do pop to mind:
1 - 2nd hand set from someone who wants to upgrade here on the forum.
2 - These batteries http://www.dixonbatteries.co.za/dc105dt

They are not sealed so do require water checking and all that so that is sorted and all cabling for them will fit the Trojans T105RE's.

If you are interested, others agree, I can send you the documentation on them.

I.e. at 20% DOD, they could get 1100 cycles, at 50% DOD, about 600 - so try for 20% DOD to learn.

So start with less hours off-grid, see what the batts tell you, then increase the load and once you are comfortable, go for broke and run the hard.

Then you go for the Trojan IND range, either 2v, 4v or 6v with 2800 cycles at 50% DOD ranging between 1270 and 1849 amp hours ... If you can charge them. 

[superdiy]

16 hours ago, Neb said:

On a sidebar, would it make sense to have freestanding aircon (heat pump) 1500W with temperature programmed at 20degrees Celsius in the DB room to keep the bank and inverter cool on hot days?

Not 20°C, but rather 25°C. Batteries are rated for 25°C and if they are operated at higher temperatures their service life is reduced dramatically.  Keeping the room at 25°C instead of 20°C will also reduce aircon energy consumption a lot.

[Neb]

Shot superdiy

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[Neb]

Interesting !

http://pqrs.co.za/s-a-solar-pv-list-2/

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[___]

There is something else that worries me a little, and that is hybrid inverters with large solar arrays but small battery banks. On another thread someone touched on this already, that when a large load turns off, sometimes there is a spike of charge current before the charge controller backs off. I also know that with Victron Hub-2 setups (GTI tied to the output of the Multiplus/Quatro) there is a rule that the GTI cannot be larger than the inverter it ties with, probably for the same reason, that large loads suddenly turning off tends to push power either into the grid (if you feed back) or into the batteries, at least until the electronics react. I suppose that it is entirely possible to react within a cycle or two, but I still have a feeling that one ought not push the limits. With your very large 9kw array, I'm thinking your batteries ought to be in the 500Ah to 900Ah range.

Now, you want to be able to comfortably handle your house load. Assuming it is similar to mine, around 500W or so (with some spikes for the kettle, microwave, and so on), you want 500W to be around the 20C mark of the batteries. 500W at 48V is around 10 amps (more or less), so 200Ah will do. Just. I'd rather go for 400 (but I don't have that kind of money right now :-), otherwise your 2kw kettle/microwave loads gets a little tense.

You're asking about cheap batteries. If you find any, let me know. The Trojan batteries are some of the best bang for buck batteries for now.

[Mike]

2 hours ago, Neb said:

Interesting !

http://pqrs.co.za/s-a-solar-pv-list-2/

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I like , i see i have been ranked 11th in S.A for under 10kw systems......

you can get Ritar 12v 260ah for around R4900 excl each, they are agm's

[Neb]

Thanks Plonkster.

Yes! definitely not wanting to push the limits at all, that was my thinking behind using a system that is pretty much twice the capacity it needs to be (except the batteries).

My understanding is that in the middle of winter with less daylight hours, my array should still sufficiently charge the bank(?).

The biggest single load I will have is probably a pool filtration system, 1.75 kW running off a variable speed drive and only in sunlight conditions!

The most power I think I could draw at once is about 5-6kw, and that will only happen if I make it happen on purpose.

That Imeon is rather heavy, it feels like 50-60kg, lots of copper in that thing and maybe a capacitor to handle a spike, I'm not sure. Your theory about the spike load is interesting but in my setup I don't imagine being near the limits (except on the batteries, but the systems not connected yet so I can change it)

If I understand Plonkster correctly, the spike problem would be solved by employing bigger battery capacity?

The batteries, I can either get 4 of those Ritar 260Ah that Mike mentioned (1040Ah), thanks Mike! or get another 4 Trojans(800Ah). Economically the Ritars make more sense, are they good reliable quality?

I'm also going to check out some bigger Trojans, I like the idea of keeping the battery units minimum, less units to replace!

Well done Mike!, Is your company called Thorne Solar?

Thanks for the help, looking forward to connecting this puppy and ironing out the bugs.

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[superdiy]

16 hours ago, Neb said:

The batteries, I can either get 4 of those Ritar 260Ah that Mike mentioned (1040Ah), thanks Mike! or get another 4 Trojans(800Ah). Economically the Ritars make more sense, are they good reliable quality?

One thing to note and let's assume we refer to batteries of the same type/model and age (don't want to upset anyone by getting too technical  ):

• If you connect the batteries in series, the voltages will add up and the amp-hour rating will stay the same, e.g. 4 x 12V 100Ah batteries connected in series will  give you a bank of 48V 100Ah.
• If you connect the batteries in parallel, the voltage will stay the same, but the amp-hour rating will add up, e.g. 4 x 12V 100Ah batteries connected in parallel will  give you a bank of 12V 400Ah.

In your case your inverter requires a 48V battery bank, so 4 of those Ritar 260Ah 12V batteries will give you a bank of 48V 260Ah, not 1040Ah.

 

[superdiy]

Something else to mention while we are on this topic, for various reasons it is better to have one string of cells or batteries with large Ah ratings connected in series than to have two or more parallel-connected strings of smaller Ah ratings.

The following jumps to mind if I think of parallel battery strings consisting of smaller Ah cells/batteries:

• More battery balancers
• Fusing required per string
• Equal resistance in cabling etc. per string
• All the associated problems / fireworks when a cell fails (shorted) in one of the parallel strings 

[Guest]

And I want to add ... make sure the charger has enough amps to charge the batteries.

[Neb]

What's the highest Ah rated 12v battery on the market available in SA?

Shot again. Ok so in parallel the voltage stays the same and Ah multiplies? In series voltage multiplies but Ah stays the same.

So what I have now is only 100Ah 48v.

No way I'm going with 5 strings!

Rather 2 strings of the Ritars.

I know this is simple stuff for you guys but thanks again, good forum.

It's making more sense now.

So I want something like 24v 250Ah +? That would be 2 strings of 2 and give me 500Ah 48v......

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[Neb]

Would it be OK to connect batteries in parallel and use a 1:4 DC transformer to up the voltage?

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[Neb]

It seems that transformers don't work on DC.

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