Charging battery using both wind and PV.

[Blah]

Hi all.

Some questions for you guys regarding my system. It provides power for a remote astronomical observatory.

Loads are light, but seeing most usage is at night, I'm wanting to augment input during the dark hours, so I've aquired a small windgen (Air-X 400 W).

What is the best method to connect the windgen to my existing setup? Any tips, tricks, hints, dos-and-don'ts and HowTos would be most appreciated.

At the moment I have two paralleled banks of six Hoppecke 660 Ah 2 volt FLA cells (ie 1320 Ah @ 12 volts).

Up to now I've been charging them via five paralleled Sharp NE-80EJE 80 Watt panels (ie 400 Watts @ 12 volt nom.), with any topping-up charge being performed with a gasoline generator.

The panels are connected to the battery banks via a Steca/BP Solar 30A PWM regulator (GCR 3000M).

As I understand it, I'll need a seperate regulator for the wingen to shunt output to a dummy load when necessary as the internal Air-X regulator won't do it. Correct?

Can I then directly connect the new windgen regulator's output directly to the battery bank bus bars?

I'm assuming I'll have to switch the GCR 3000M to voltage regulation instead of the default SOC method it uses out-of-the-box.

Can I connect the new windgen to my PV system or will I have to have seperate bank for it?

Thanks in advance for any help with this!

Blah

[kurt]

doesn't the air-x have an internal regulator that is supposed to short the gen when the batteries are full??? i would suggest reading the manual see what it recommends. btw i don't think you are gonna be very happy with the air-x unless you have an exceptional wind site. i have heard many bad things about the air series.  but seems as how you already bought it you mite as well install it and see for yourself.

[Blah]

Hi Kurt,

The Air-X does have an internal regulator but I'd rather use an external device so that I can make use of the energy it continues to generate when the battery bank is full.

My site has excellent wind conditions which will suit the little Air-X quite well. I've read the criticisms of it previously but they usually come from people with the resources to purchase vastly more expensive machines than I can.

I got a new Air-X very cheaply, so I can't complain. I can't afford anything "better" either, so I'm happy to make do with what I have! ;-)

But leaving the Air-X bashing and heading back to the original question: can I safely connect the Air-X directly to a battery bank which is already connected to a PV-based charging system?

Thanks!

Blah

[TAH]

Unless you are using the generator very regularly to keep the batteries charged you will probably have very little extra power to worry about using out of the air-x. It would be much easier to use it as is and if you really want to use the extra power monitor the battery voltage and trigger your extra loads before the regulator in the air-x cuts back.

[Blah]

Hi TAH.

I don't have to use the generator very often. I don't live at the site and generally only run the telescope drives, a 12v mini-ITX based computer, and occasionally the red LED lighting. My loads are very low relative to my battery bank capacity.

The PV array gets excellent insolation, with no shading other than night time darkness. It's a relatively high altitude site and usually above the clouds in this area.

The windgen will hopefully permit me to use the gasoline-powered genset even less, as well as heat either air or water as a side benefit.

Do you know if it's okay to connect the windgen output directly to the battery bank busbar (via an external shunt-type reg)?

Thanks guys,

Blah

[ghurd]

"Do you know if it's okay to connect the windgen output directly to the battery bank busbar (via an external shunt-type reg)?"

Yes.  That's fine.

But. It depends on the wind gen and the controllers involved.

The external shunt, diversion, or dump type controller would do it... IF the load is large enough.

Like Kurt said, the Air-X is not likely to do a whole lot.

The state put a bunch up along the highway. They don't even turn very often.

With the loads I understand there are, and the insolation, it could be a better idea to have a little more solar and/or battery.

Maybe the controller in the Steca voltage could be set a bit higher?

Someone is sure to point out we have NO idea where this is.

Mt. Everest? AZ? NM? NH? Africa? North Pole?

We don't really care, but the guesses will be closer to answers.

G-

[Blah]

Hi ghurd.

The site is in New Zealand.

Wind is a feature of life on the site and so far the Air-X is doing fine. I have it test-mounted and it's putting out plenty of amps into a relatively small, temporary bank.

I have a bunch of big resistors in the 0.8-2.0 Ohm range, so the dump load shouldn't be an issue.

It'd be nice to get some more solar panels but, at NZ$10 per watt, I'm not in a position to do that. The Air-X was inexpensive and new, so it was affordable. (I got it from a boating friend who retired from sailing before he got the chance to install the windgen on his yacht.) :-)

As far as I know the solar reg voltage is fixed and not moddable. When I can afford it I'll upgrade but for now that reg is "it".

Thank you for answering my question! :-)

[Flux]

I assume your present solar controller is the type that open circuits the panels and that will not be satisfactory for wind unless you use the Airx regulator.

By far the best thing to do is feed the panels and unregulated Airx directly to the batteries and obtain a charge controller that can be used in diversion mode. It will then handle the wind and solar properly and its charge algorithm will be correct for the batteries without being confused by 2 sources. Using mixed controllers is not ideal and I am not sure that your existing solar controller has ideal charge characteristics anyway.

Flux

[Blah]

Hi Flux

As far as I can tell, the GCR 3000M is a BP Solar-rebranded Steca model. It doesn't have a diversion control feature which is why I'm planning to obtain a diversion load controller for the windgen (which also doesn't have one built in).

Do you know of any MPPT-type solar regulator/controllers which have an integrated diversion load controller and/or windgen input provision? I know Morningstar's TriStar can do it, but that model is PWM like my BP Solar/Steca, not MPPT and for the price I could add another one-and-a-half solar panels! :-)

Re your reply to my original question, I'm a little confused. Should I connect the *unregulated* output of the panels and windgen directly to the batteries? Or did you mean connect them via a new regulator? Your wording left me scratching my head a little, sorry.

The vilified Air-X windgen has an integrated regulator, but it doesn't have a diversion load control facility, and I would rather let the windgen operate constantly, diverting the excess energy to a diversion load, rather than let the internal reg simply stop the turbine when it senses that the battery is fully charged.

The GCR 3000M solar controller can be switched between State of Charge mode to Voltage Control mode. If it's in the latter, can I use the existing system correctly and safely, if the windgen output is connected directly to the battery bank (via an external diversion control regulator)?

My original concern was that having the windgen's output feeding directly into the battery bank (bypassing the PV reg) would cause the PV reg to not function correctly. I'd hoped that by switching it from SOC to Voltage Control mode I could avoid the problems, but wasn't sure if the solar reg would become "confused" or even damaged when it sensed the additional new input from the windgen.

Thanks for your reply and any further answers would be greatly appreciated! :-)

Blah

[ghurd]

"My original concern was that having the windgen's output feeding directly into the battery bank (bypassing the PV reg) would cause the PV reg to not function correctly."

You have the Air-X amps going through a solar controller?  That's not good.

A diversion controller doesn't care where the power came from.  It simply gets rid of the 'extra'.

Might look at a C60.  Then connect the solar straight to the battery. Connect the unregulated Air-X straight to the battery.

G-

[Flux]

Sorry I don't know of any mppt controller that will accept the solar and wind. It does make sense to try to get the maximum out of the panels with mppt. I would imagine you would need to set the mppt controller volts high, add the wind directly to the battery and then use an extra diversion control, all complicated and expensive. I was just thinking of connecting the panels and wind direct and using a diversion controller.

What I meant in the first case was that without a diversion controller you would keep your series switched controller for solar and to add the wind you would need to connect the AirX direct to the battery( it mustn't go via the solar controller, it will kill it ). To prevent the batteries being overcharged you would need to retain the AirX regulator. Not a perfect solution but it would work. I can see why you don't like the internal regulator in the AirX, because it reduces the power out of that machine as soon as it regulates, but I have a feeling that it does that to reduce speed and noise in high winds anyway ( not sure if you can over ride that speed limiting even if you set the regulator volts up).

Unless you could use the heat from the diversion load then keeping the Air X regulator would only be an issue at times when things are fairly well charged anyway so it may still make sense.

Flux

[Blah]

Hi again Flux.

Yeah, the heat from a diversion load would be very useful up on the mountain, either for room or water heating. It gets very cold up there. I was thinking it'd help keep the battery room at the right temperature. The room is heavily insulated (6" styrofoam) but having some heat imput would be useful. That heat couls also or alternatively be used to keep the water supply from freezing (tank and pipes, etc).

From what you and others have said, I'll obtain a diversion load controller, probably a TriStar and hang it off the windgen, connecting the output directly to the battery bank busbar. Hopefully that'll work without causing too many problems, especially if the solar reg is set to a fixed voltage in voltage control mode.

It'll be nice to know during the night that I'm charging the cells even as I'm using them. :-)

Thanks for all the info, guys!

[Blah]

Hi again ghurd.

No, the Air-X output isn't connected to the battery bank via the solar reg. My plan was to connect to wingen output to the bank via a seperate external diversion load controller. My concern was that the solar reg would become "confused" (or even damaged) when it sensed the bank voltage change caused by the windgen input into the bank.

My fear was that it may not charge (from the PV array) properly, but I figure that if I switch the reg from SoC mode to Voltage Control mode (a fixed reg voltage) the reg would be able to handle a bank with a second charging source connected to it.

The solar reg is not a diversion load controller type and the windgen's internal reg won't do that either (it'll just brake the blades if it senses the bank voltage as being charged). I want the windgen to keep operating constantly (except in dangerous winds) so that I can make use of the "spare" output, for things like air and water heating.

I have the Air-X connected to an old and small temporary bank which runs an inverter which I use for powering tools and a radio, etc, because I'm still in the construction phase. The load is pretty high, so the windgen is going continuously. I'm not certain what problems others had with the Air-X, but this one runs like a trooper, providing lots of amps even in quite light winds. The battery bank has never dropped very low and is charged up quickly again once I stop work.

I'll obtain an external diversion load controller (a TriStar or Xantrex if I can get one cheap) and hang it off the Air-X. I'll use some 1 Ohm-ish resistors as the diversion load. I'll connect the controller output directly to the same battery master busbars the solar reg is connected to. Hopefully this won't be a problem. If necessary, I can always switch off the windgen until nightfall.

If anybody is interested, I'll post the results here at a later date (once I have a diversion load controller to connect, etc.)

Blah

[DamonHD]

For reference, the "MWI" inverters at the bottom of this page:

http://www.power-one.com/renewable-energy/wind-inverters.html

I understand they claim to be that these take wind and PV.  They may be MPPT.

Rgds

Damon

[jonas302]

can you adjust the automatic shutdown on the mill? Dump power at the batts keeping the voltage down allowing the mill to keep  turning

[Blah]

Hi jonas302.

I thought about that but, if I crank the Air-X internal regulator way up, maybe I'll just overcharge the cells?

The second option just seems wasteful - burning volts just to keep the charger going! And I'd never get any heat from the dummy loads! :-)

[ghurd]

I think you have a misunderstanding of how a dump load works and what it does.

If the mill is set to 16V, the solar has no controller, and the dump controller is set to 14V, the batteries will never get past 14V.

The mill will keep going, the solar will keep charging, but the dump controller will keep bleeding it out to maintain the battery at 14V because that is what they do.

G-

[Blah]

Hi ghurd.

If I have no regulator on the PV array, what's to stop them boiling the cells? The battery bank loads are very low. Even after a long winter's night of use I've barely taken anything out of them. When the sun comes up and the amps start flowing, won't I have an issue?

The dump load kicks in once the diversion load controller senses the battery voltage is at the preset level (whatever it may be) while the windgen is still operating, thus preventing the cells from being overcharged, yes? If I mod the windgen charge voltage up to it's highest setting, won't that risk overcharging the cells, bearing in mind that there's never much of a load drawing them down most of the time?

I don't have much of a problem keeping the cells topped up most of the time. What I'm really trying to achieve is gaining energy from the windgen in the form of heating which otherwise wouldn't be there because the windgen's internal reg would normally brake the blades once the normal preset battery voltage level was sensed.

And I want to make sure I don't connect anything in such a way that the system is damaged, or becomes inefficient.

Blah

[Blah]

"The dump load kicks in once the diversion load controller senses the battery voltage is at the preset level (whatever it may be) while the windgen is still operating, thus preventing the cells from being overcharged, yes? If I *have no diversion-load controller* and mod the windgen charge voltage up to it's highest setting, won't that risk overcharging the cells, bearing in mind that there's never much of a load drawing them down most of the time?"

Clarified...

[Flux]

Having seen more of what you are doing, it seems to me that you would gain little from an expensive mppt solar controller as your solar seems capable of what you need without it.

I can appreciate that the heat from the diversion controller will be of advantage at night and the solar will do nothing there.

In this case I would not spend extra money on a mppt controller, at the present time there are none for wind.

One good diversion controller will take care of everything, the solar can be connected direct to the battery and so can the wind ( either set the wind controller to it's highest setting or disable it in some way). If the solar gets the batteries well up during the day you will have the full wind capability at night and the benefit of any excess in the heater.

Just to clarify one of your points, the AirX is fine, it is a high wind area machine and you have wind. The complaints come from people in low wind areas ( most of us), it does nothing in winds below 10mph. It works well on boats at sea and decent wind sites like yours, it is virtually useless on poor inland sites.

Flux

[Blah]

Hi Flux.

Once again I have to say I'm a little apprehensive about connecting unregulated charging sources to my battery banks. The cells I need are hell expensive and I can't afford to be cooking them. I'm not always at the site, sometimes for weeks if the snow is very heavy or the spring thaw turns the track to mudpies, so the risk is that the electrolyte could boil away before I discover it in time.

If I had heavy loads constantly discharging the cells, I wouldn't be so concerned about overcharging, but at the moment the loads are so light that really I'm just keeping them in a float state much of the time. Without regulation, I can imagine the PV array doing some real harm.

Hopefully I'll be able to get hold of an affordable diversion-load controller for the windgen and also keep charging the banks with the PV array via the 30 amp PWM reg for now. I expect that in the future my loads will increase but, if all goes according to my cunning plan, so will my budget and I'll be able to afford an MPPT controller.

I just want to say thanks a lot to you guys for all the suggestions and help. It's much appreciated!

Blah

[AbyssUnderground]

It sounds like you still can't grasp how the dump load controller works... It will NEVER let your batteries become over charged... EVER. It uses the excess power from BOTH charging sources meaning there is no extra power available to over charge the batteries.

[Flux]

If the dump load is sized to dump more than the combined wind and sun input then the batteries can't be overcharged.

If you are unhappy then it is perfectly ok to leave the solar series controller and let the diversion controller only take care of the wind. In that case the dump load could be smaller but it may still be wise to rate it for the total input as a precaution.

The main objection to using multiple controllers is that no one controller can decide on the exact charging parameters. The existing solar thing may not be very sophisticated in this respect and it may not let a decent high quality diversion regulator charge batteries to best advantage, but using both is still possible.

Leaving things unattended for long periods is rather more worrying than schemes that are monitored daily, but there are remote telemetry and other things that fall into this category and they survive. Just make sure you are sized for more than the total system can produce.

Flux

[DamonHD]

Hi,

I am today or tomorrow going to build my ultra-simple shunt regulator for wind.

PV is my primary source, and I trust my MorningStar controller to do relatively clever battery management.

Wind is a secondary source and only a little extra power.

I'm just going to use a crowbar overvoltage circuit to short out the wind turbine upstream of a diode to the battery when the battery appears to be charged.

I am considering putting in another set at a slightly lower voltage to to dump into some 1Ohm loads.  You could use this stage to dump into your heating elements.

Ignoring the dump resistors, each stage takes 4 components and should handle much more power than my turbine can ever generate with ease.

If the wind starts to produce a bigger slice of the power then I have GHurd's dump-controller kit to hand to give me more finesse.

I expect my system to remain essentially entirely maintenance free.

Rgds

Damon

[coldspot]

Blah-

"you have a misunderstanding of how a dump load works and what it does."

 Solar panels to Battery bank, with or without that controller, (if with turn it up a bit on the voltage), Wind Turbine to battery bank, DIRECT!

THEN, you hook up the "Dump controller".

To the Bank not between the turbine or the PV's to the bank, Direct to the bank!

When the bank is full,(as set by the dump control voltage setting), and extra power is going into the bank the dump controller starts to dump this extra power to the heating elements. What ever source this power is coming from, PV or wind, all extra power is drained off the bank not sent some place else, the power still goes into the batteries but the dump is drawing off the bank to keep them from overcharging.

 I hope you can understand how it works.

(I hope I drew it out right)

[ghurd]

I'm not sure how many people can explain it in how many different ways,

but I will try one more time.

You seem to want to regulate the solar and wind and battery separately.

But you want to use the extra power.  There isn't really a good way to do that.

The idea of a dump controller is to regulate the BATTERY.

Solar and wind make all the power they can make. They send it to the battery.

When the battery has all it needs, the dump controller regulates the BATTERY by sending the extra power to the heaters.

If the wind and solar are regulated, then there is no extra power for the heaters, because the other regulators do not allow that power to be made.

Here is a sketch of my dump controller circuit and battery.

Notice there is no solar or wind or hydo or anything shown, because it does not matter. And whatever it is, it is not regulated.

The controller keeps the battery voltage at the maximum you decide. The controller regulates the battery.

http://www.otherpower.com/images/scimages/2050/CtrlSch.gif

G-

[Blah]

OK. You guys are saying the dump load sheds excess energy from the battery bank.

I was under the impression it was needed to divert away from the bank the excess energy generated by the windgen.

All of the diagrams I've ever seen for hybrid systems show the diversion controller on the windgen output and a normal solar reg on the PV array output (because the solar reg just disconnects the array when it senses the full charge).

One disadvantage I can think of when using the diversion load controller to dump the excess from the combined input is that during the day the solar panels might supply almost all of the power and my windgen's internal reg will shut off.

But at least I'll only need one controller now!

Thanks for your patience guys, I'm finally starting to see the light.

Blah