Adding Solar to Wind

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Adding Solar to Wind

Postby Scott B » Fri Jan 15, 2016 3:13 pm

Hi, I am back with my question. As I mentioned in my introduction, I have a 48V system to provide power to a 2x1 Transportable in the country where it is too costly to connect to mains. Currently the HM4.0-3000W Exmork Energy turbine is connected to FKJ-A2 (?) hybrid auto controller then to a HBC P3000VASW inverter/charger and 4x Vision 120Ah 12V AGM batteries. All the equipment came with the property but the batteries are brand new. Last time I had the batteries connected the turbine started turning and the FKJ was indicating 6-8 amps output which I was pretty happy with. The inverter was showing inverter mode not charging but I assume this was only because the house was drawing a current. So all that seemed to be fine, lights, tv and fridge were working. I also inherited 3x 250W Renesola panels and a Morningstar 60 MPPT controller which werent connected. I was at first stumped as to why the previous owner had bought/found only 3 panels but I now assume this is so when they are in series they are above the 48V limit to push the charge into the batteries. Now for the question, I know you would need the MPPT controller if I was only on solar but since the FKJ is a hybrid controller do I connect the solar panels directly into the auto controller or do I have to/is it better to go through the MPPT first?
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Re: Adding Solar to Wind

Postby Gordon-Loomberah » Fri Jan 15, 2016 3:59 pm

I didn't find the HM4.0-3000W wind turbine, but did find the ZH3KW Exmork, and it's way too big to connect to a small 120AH battery. Max output is 3500W, at 50V that is 70A, which is likely to damage a 120AH Lead-acid battery.

I'd connect the 3 panels to the Morningstar MPPT CC and that to the battery, not via the hybrid controller, as the Morningstar is designed to be connected directly to a battery, rather than another controller of potentially incompatible behaviour.
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Re: Adding Solar to Wind

Postby Scott B » Fri Jan 15, 2016 5:27 pm

Thanks for the reply Gordon, I would have thought 70A would be too much for any size battery! I thought the turbine controller took care of the charging current so that in the event of the turbine actually putting out 3000W (~60A) it would only send through to the battery what it could handle, the rest being sent through to the load dump? The documentation for the HBC goes through a calculation to determine battery size based on a consumption assumption and recommended only 200Ah battery in that case, not much bigger than what I have. What size battery were you thinking it should be? If it helps I can provide the manuals for the turbine, turbine controller and the inverter/charger that I have. As far as I know, the turbine, controller and inverter were sold as set (but seller is now offline), what batteries went with it I dont know. I believe they may have been second hand even when it was installed.
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Re: Adding Solar to Wind

Postby Scott B » Fri Jan 15, 2016 6:02 pm

Looking at visions home page I see it would be good to have at least a 300Ah 2v x24 battery bank in case the max ~60Amps is generated. Max charge current for 120Ah is only 36Amps. I couldnt see anywhere in my equipment documentation that a minimum Ah battery is required, just that it needed to be 48V. Hmmmm
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Re: Adding Solar to Wind

Postby Gordon-Loomberah » Fri Jan 15, 2016 7:30 pm

I hit my 400AH LiFePO4 with over 100A fairly often :) However, Lithium can easily handle much higher currents than Lead-acid.

The charge controller only limits the charge to a set voltage, unless it is able to be programmed to a lower current. If the battery is fairly flat, then it could easily exceed 36A and not exceed the Absorb charging voltage (Vabsorb).
Battery size is generally determined by consumption and limits to depth of discharge before you want to use a generator, but the old calculations which favoured buying more batteries due to high PV panel pricing don't necessarily apply, now that panels have dropped so much in price. It's better to go large with the PV and save money with a smaller battery, while making allowance for your overnight energy use and the max power that the battery needs to absorb from your solar and wind generator.
The wind turbine will probably put out more than its rated capacity, but that would be a rare event. At what wind speed is it rated at?
I'm not sure of your location, but one thing you may not realise is that in almost all of Australia, solar will produce more output than a small wind turbine for the same equipment cost.
It is generally best to have solar as your main generator, and wind as a supplement.

I can't recommend a battery size for you without knowing consumtion, location etc details, but just based on generator size, I'd suggest 300AH minimum. You do probably need to double or triple your PV panel array size though.

If the batteries are 2nd hand, their capacity may be somewhat less than the rated capacity.
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Re: Adding Solar to Wind

Postby Scott B » Sat Jan 16, 2016 11:09 am

Gordon, I think I have confused you a little, the batteries are brand new, the equipment is 2nd hand and probably was when last owner acquired them. "just based on generator size, I'd suggest 300AH minimum" thats the answer I was after, but answered myself looking up the battery specs after your prompting. I'd never thought to consider max charge capacity before. Where we are is quite regularly windy so I'd imagine it producing a significant amount of power. At this point in time I just want to maximise what we have before expanding anything so battery size is driving consumption rather than the other way round. If the turbine (design life supposedly 15 years and I dont know how many of them are left) ever stops working I will just let it go and move onto solar only but in the mean time if it works I'll use it. Hypothetically, if I added a second string of 120Ah batteries to make it a 240Ah 48V system would that mean I have a max charge current of 72Amps? Not that I will do that in a hurry, having just bought the property I am still recovering from all the transaction fees and charges so apart from some new batteries I wont be buying anything in the short term, but would be looking at something like 12 panels long term. Turbine is rated 3kW at 10m/s, 3.5 at about 12. Has a 100A fuse. Thanks for your comments, they have given me a lot to think about and a better understanding of how the system works.
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Re: Adding Solar to Wind

Postby Gordon-Loomberah » Sat Jan 16, 2016 12:28 pm

Yes, if you added another string of the same battery, you could charge at twice the rate. Remember though, that max charging rate is probably for 25 or 27C - at higher temps it will be lower, but at lower temps you could safely go a bit higher.
However, if you think you may need more than double your existing battery capacity, it may be worth thinking of starting afresh, rather than adding more parallel strings of 12V batteries. One is best, 2 is ok, 3 is pushing things a bit- sure it will work, but you dramatically increase your chances of premature failure as the cell count rises, especially if high charge and discharge rates occur, and 12V batteries in parallel maximises cell count. It would be worth thinking about a Lithium battery, which can be more heavily discharged without shortening the its life, as happens with deeply discharged Lead-acid batteries. Large 2V Pb-acid cells are another option.
Realistically, if you plan to discharge no more than 25% depth of discharge each night to give the batteries a reasonably long cycle life, you have under 1.5kWh available with the existing battery. That will cover the fridge, TV, lights, phone chargers, etc ok, but you would have to limit any other large loads. On cloudy days you will have to use a generator extensively if it isn't windy enough.

If your ambient temperature (at least around the batteries) varies much from ~20 to 30C, you will need a temperature probe on the batteries, so that the charge controller can compensate, raising Vabsorb and Vfloat in cold weather, and decreasing them in hot weather, to protect from under and overcharging respectively.
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Re: Adding Solar to Wind

Postby Gordon-Loomberah » Mon Jan 18, 2016 2:03 pm

BTW, how high is the tower for your wind turbine, and how high are any obstructions in the vicinity - ie up to ~100m away?
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Re: Adding Solar to Wind

Postby Scott B » Mon Jan 18, 2016 2:34 pm

12m high tower. Mostly empty paddock except for the transportable and a few small sheds nearby, which are necessary since you need the controller/batteries less than 40m away. The house probably does affect it if the wind comes from that direction but its not its predominant direction. The main directions are fairly clear of major obstructions. Put it this way - I aint shifting it! :)
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Re: Adding Solar to Wind

Postby Gordon-Loomberah » Mon Jan 18, 2016 3:11 pm

OK :) how about lifting it up a bit? ;)
The higher you mount the turbine, the more energy you'll get out of it, and for a 3kW unit, 12m is on the low side of ideal.
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