Adding wind generator to solar array

Joesouth75 · April 2018

Hello all. Here's what I have. 6 panels 320w each 24v. I have a Midnite classic 200 with 2 banks of four t105 batteries 24v each leading into a 3000w inverter.
I'd like to add a wind generator to continue the charging during night time hours. I don't need anything massive just enough to keep the batteries charged. Does anyone have experience with this? How is it tied into battery bank? Recommend a wind generator? Schematics?

mike95490 · April 2018

My suggestions

1) if you don't have to tie your hat onto your head, you don't have enough wind to bother with

2) you have maintenance chores at the top of the tower, 2x a year.

3) you will need a new controller, and likely a Dump Load rated 2x the wind turbine output

4) get a smaller inverter, unless you have some load that comes on middle of night that needs 3Kw. The idle losses can be killer

Joesouth75 · April 2018

I have a composting toilet that runs a fan 24/7 and a well pump that could come on at anytime. It seems the toilet fan draws batteries down overnight. I'm just looking to maintain them in the dark hours and on cloudy days.
If a wind generator would work, the 2x maintenance would be worth it. Anther controller was expected. Any other thoughts? Anyone?

littleharbor2 · April 2018

Wind generators only make power when the wind blows. No wind, no power. We're talking, constant significant wind, anything less and you'll be disappointed.

Your money might be better spent on a few more panels. Are you getting back to full charge everyday?

Maybe your batteries are getting tired. How old are they? Have they been maintained/equalized regularly?

Do you need the well pump to run overnight? If not you could shut down the pump and big inverter and run a smaller inverter. This might allow you to not need to add any wind or panels to your system.

Estragon · April 2018

I think some composting toilets not only run a fan constantly, they also run a heater. Just running a fan to move enough air to prevent it going anaerobic shouldn't be much of a load - a 3000w could use more just staying lit than such fan alone. Add a heater though, and the load could be much more of an issue.

If it's just a fan, I'd consider a separate small inverter or possibly a DC fan (maybe even a dedicated battery/pv). If there's a heater, I'd consider alternatives, such as alternate supply of heat or even alternative toilets before wind.

FWIW, I looked into wind a few years ago. I get by fine with pv in spring & summer, but in fall and winter the sun is too low, too weak, and too short. It tends to be more windy though, hence the interest in wind supplement to solar. Long story short, estimated cost got to well over $10,000 and realistic power production was pretty marginal. I suspect if I had pursued it with testing of actual wind in situ, installation costs would have risen further to get to needed siting and/or realistic production even more marginal. It would take multiple lifetimes of avoiding generator runtime to break even, and wind is still intermittent enough to not eliminate it entirely.

Even if your site has much better wind potential than mine, I'd suggest looking more carefully at the load first.

Joesouth75 · April 2018

Batteries are new last Aug. I believe they are being fully charged each day. And EQ runs once a month. Is that enough? The well only runs when the pressure tank drops in pressure so no not usually overnite. It's the toilet fan that draws the batteries down.
Does the inverter really draw that much? Maybe that is my problem? Is there a ratio between panel watts to inverter watts? Or can I have 2kw of panels and 1000 watt inverter?

706jim · April 2018

Curious as to what sort of toilet fan you are using. I have a Sun Mar Centrex system and used a 24 volt computer fan on a 12 volt supply. Current draw was in the milliamps and fan ran 24/7. Eventually I found that chimney effect was adequate for venting and scrapped the fan altogether. If you run a heater that is a whole other story.

mike95490 · April 2018

The ratio is:

Loads force the size of inverter & the battery size to support the loads & inverter overhead

PV is sized by your winter sun hours (2nd worst month) to maintain your battery bank (400ah bank needs 40A of charge)

It's hard to believe a 10W fan is causing the battery problem 10W x 12hours = 120 watt hours, solved by 200w of PV

Does your charge controller have any indicators on it, that signal what stage of charge it's performing ? Bulk, float, Absorb? Batteries generally need 2 hours of Absorb - and even then, they are only about 90% full. You may have to increase your Bulk voltage to cram enough power into the batteries.

Estragon · April 2018

My guess is a 3000w inverter will run ~30-50w just being lit. 50w x 24hrs = 1200wh, in the ballpark of what a fairly efficient fridge might use in a day.

450ah@24v is ~10,000wh, keeping DOD to 50% is ~5,000wh usable, so could be on the order of a quarter of usable bank capacity to keep the inverter lit.

littleharbor2 · April 2018

If as Estragon says, there's a heater involved then there's part of your problem. Creating heat, or cold, for that matter is taxing on battery systems.

Some better inverters have lower tare losses than others. Look up your inverter and see if you can find the idle power consumption., multiply that by 24 hours, you may be surprised at the results. some inverters burn more power doing nothing than an energy efficient fridge.

You can have as small an inverter as you need for low power consumption times. The Morningstar 300 watt PSW inverter can legitimately surge to 600 watts and, I believe, is a sensible addition to many off grid set ups. There are problems when your inverter and/or load is too big for your battery bank. In your case it sounds like either a heating element or inverter losses, or both.

Estragon · April 2018

Panel watts and inverter watts aren't directly related, although battery capacity can be a factor in both.

I run a 300w inverter on a 700ah@12v bank with 1000w of pv, which works fine in my application. I also run stacked 3.5kw inverters for 7kw total on a 350ah@48v bank with 4.5kw pv, which runs pumps, etc. The big inverters are usually off or sleeping at night.

Joesouth75 · April 2018

The only reason I have such a large inverter was due to my pump start up peaks at 1600w and the 3000w inverter was on sale so... Now that I've read all these replies I believe it maybe the inverter sucking the batteries.
No heater on the toilet. Just a fan.
So a smaller inverter for night time use. Very good idea.
I have a 24v system, are there any advantages to a 48v system? Other than wire size.
Anybody live near Pembine, Wi you are more than welcome to stop over and check this system out.

BB. · April 2018

If all you need the inverter for (at night) is the fan--Get a DC computer fan... They are available from 12-48 VDC pretty easily. A 48 VDC van on 24 volts will spin much slower and be very quiet.

https://www.jameco.com/shop/keyword=Fan-Dc-48-Volt

Regarding the AC inverter... Nominally, a T105 battery bank with ~215 AH @ 6 volt batteries (flooded cell?) with 4sx2p strings... That is a ~430 AH @ 24 VDC bank. And would suggest an AC inverter in the range of ~~1,050 Watts to ~2,115 Watts (typical max AC inverter for flooded cell 24 volt battery bank would be ~500 Watts per 100 AH of 24 volt battery bank). Also, typically ~2,115 Watt solar array would be a suggested maximum cost effective.

There is no reason to go with a 48 volt battery bank unless you are looking for a larger battery bank/AC inverter/Loads. The higher voltage the battery bank, the more difficult it is to find smaller AC inverters.

Here are some smaller 24 VDC input AC inverters that may be of interest from our host (NAWS):

https://www.solar-electric.com/residential/inverters/off-grid-inverters.html?nav_inv_input_voltage=24+Volts&sine_wave_type=Pure+Sine+Wave

You can get down to ~6-10 Watts Tare Load for 600 Watt or less 24 VDC Sine Wave inverters.

If you can wire your well pump/large inverter system to only run when the pump is running--That will probably save you a bunch of stored energy.

Another thing, get a relatively inexpensive DC Current Clamp Meter and measure your inverter's current (if you do not already have a shunt based battery monitor). DC Current Clamp meters are great for answering these sorts of questions, and for debugging electrical systems (AC and DC) in general.

http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P (oh darn, this $60 "good enough" meter is no longer available?)
https://www.amazon.com/gp/product/B019CY4FB4 ($130)

There are cheaper meters available--Don't know anything about this one:

https://www.amazon.com/gp/product/B00O1Q2HOQ ($41)

DC current clamp meters are a great invention for working on DC power systems. You can simply clip on one wire and measure the current flow without having to cut the wire and put the meter in series.

Make sure you get a DC current clamp meter (really an AC/DC Current Clamp DMM). There are also tons of AC ONLY current clamp meters--They are fine instruments, but they cannot measure DC current flow.

-Bill

BB. · April 2018

By the way, one thing to watch out for... If you run the cabin in the winter, it is not uncommon that your battery bank will charge/equalize at >~30 VDC in subfreezing weather... And many inverters will shutdown at ~30 VDC. A common complaint for our friends in the great white north.

If you use your cabin in the winter, finding inverters that have ~32-33+ VDC minimum shutdown will save you some frustration.

-Bill

Estragon · April 2018

If the big inverter is only for the pump, maybe dedicate the big inverter to that load only? It may have a low power "sleep" mode, much reducing the load keeping it lit 24x7. If not, a relay activated by the pump pressure switch could be used. I use the big inverters for multiple pumps, power tools, etc during the day (often on available pv power while batteries are in absorb/float) , so the day/night thing works out for me.

Aside from wire size, 48v is 1/2 the current for a given wattage. This means more pv for given controller capacity, less voltage sag in batteries with large loads, less need for parallel banks, etc. One downside is it's hard to find good, small inverters for 48v. My little 300w Morningstar PSW inverter works really well, but unfortunately only comes as 12v.

Joesouth75 · April 2018

Thank you all. I will look into separating the pump and see what I come up with. Thanks again.

littleharbor2 · April 2018

BB. said:

There are cheaper meters available--Don't know anything about this one:

https://www.amazon.com/gp/product/B00O1Q2HOQ ($41)

DC current clamp meters are a great invention for working on DC power systems. You can simply clip on one wire and measure the current flow without having to cut the wire and put the meter in series.

Make sure you get a DC current clamp meter (really an AC/DC Current Clamp DMM). There are also tons of AC ONLY current clamp meters--They are fine instruments, but they cannot measure DC current flow.

-Bill

This one, found on eBay and Amazon is a really nice small one and really inexpensive.

Image: https://us.v-cdn.net/6024911/uploads/editor/v7/mm8s0qygfxkg.jpg

BB. · April 2018

Be careful, I am not sure, but I think that is an AC only current clamp meter with AC+DC voltage capability.

AC 600Amp AC/DC Voltage Resistance Meters

You have to read the descriptions very closely... AC 600Amp....

Bill

littleharbor2 · April 2018

BB. said:

Be careful, I am not sure, but I think that is an AC only current clamp meter with AC+DC voltage capability.

AC 600Amp AC/DC Voltage Resistance Meters

You have to read the descriptions very closely... AC 600Amp....

Bill

Yes, I own one. It does dc current.
Here's the info on it. Delete if not allowed.
https://www.ebay.com/itm/UNI-T-UT203-Digital-Handheld-Clamp-Multimeter-Tester-Meter-DMM-CE-AC-DC-Volt-Amp/252445352747?hash=item3ac6ea632b:g:fCQAAOSwHjNV99RG

ScoobyMike · April 2018

Joesouth75 said:

Thank you all. I will look into separating the pump and see what I come up with. Thanks again.

Also, look into the sleep mode Estragon mentioned as this could be implemented immediately. Some inverters call it standby mode. Basically the inverter goes into standby when the load drops below a user programmed level and then powers back up when the demand for power returns. Perfect for your pump...

BB. · April 2018

The 203 is a different model (200 shown).

Bill

littleharbor2 · April 2018

BB. said:

The 203 is a different model (200 shown).

Bill

Yes I caught that That's the photo with the UT-203 listing I found on Amazon, Sorry. Advertising error, I guess.
https://www.amazon.com/UNI-T-UT203-Digital-Handheld-Multimeter/dp/B07546L9RT/ref=sr_1_16?ie=UTF8&qid=1525050578&sr=8-16&keywords=uni-t++dc+clamp+meter

The UT-203 model is the AC/DC clamp meter. I will add, It reads the same as my Klein DC clamp meter in side by side tests and does have a good solid "feel" For the price it's a bargain.

DanS26 · April 2018

Joesouth75 said:

I have a composting toilet that runs a fan 24/7 and a well pump that could come on at anytime. It seems the toilet fan draws batteries down overnight. I'm just looking to maintain them in the dark hours and on cloudy days.
If a wind generator would work, the 2x maintenance would be worth it. Anther controller was expected. Any other thoughts? Anyone?

Joe..... put timer on that composting toilet......only run it when the sun shines.

Except when anyone notices.......then you are back where you started. Worth a try.....just don't tell anybody during the transition.......

MrM1 · April 2018

I have this one that BB posted, works very well

https://www.amazon.com/gp/product/B00O1Q2HOQ

Estragon · April 2018

> @MrM1 said:
> I have this one that BB posted, works very well
>
> https://www.amazon.com/gp/product/B00O1Q2HOQ

The detail lists this one as having a 17mm jaw, which I think would be too small for my battery wire (2/0, 4/0). Do you use it for big wire?

The 203 lists jaw opening as 28mm, which I think might work. @littleharbor2 , do you use yours for large wire?

I kept checking for the Sears one while I was in the US a few months ago, but it was always listed as "out of stock". I'm guessing Sears is involuntarily "discontinuing" a lot of SKUs these days.

westbranch · April 2018

I have a UT 210 which has a ~ 1/2 inch jaw opening.

littleharbor2 · April 2018

Estragon said:

> @MrM1 said:
>
The detail lists this one as having a 17mm jaw, which I think would be too small for my battery wire (2/0, 4/0). Do you use it for big wire?

The 203 lists jaw opening as 28mm, which I think might work. @littleharbor2 , do you use yours for large wire?

2/0 is the largest wire I have in my system. 28 mm is 1.1 inch. Typical nominal O.D. for 4/0 is about 3/4 inch.

Image: https://us.v-cdn.net/6024911/uploads/editor/ee/71orqdqj7v45.jpg

MrM1 · April 2018

Estragon said:

The detail lists this one as having a 17mm jaw, which I think would be too small for my battery wire (2/0, 4/0). Do you use it for big wire?

The 203 lists jaw opening as 28mm, which I think might work. @littleharbor2 , do you use yours for large wire?

I kept checking for the Sears one while I was in the US a few months ago, but it was always listed as "out of stock". I'm guessing Sears is involuntarily "discontinuing" a lot of SKUs these days.

I use it for 4/0. It does fit but to get a good read, you have to press the clamp together after you get it around the cable. The jaw does open up enough to get it around the cable though, at least the 4/0 fine strand that I have from Windy Nation. Once around the cable, it does close, but not perfectly tight, and when you press the clamp closed with your fingers, it does have a different amp reading, But once closed it agrees with both my Classic 150 Whizbang Jr and The Schneider SW inverter SWP readings. Seems to be more accurate and consistent than both. But that little meter does NOT have In Rush or Max current for start of motors. There are a few others on Amazon that I am looking at for that purpose.

These 3 (which look nearly if not exactly Identical) have In Rush
https://smile.amazon.com/dp/B015QSAJTM/?coliid=I106IQNJ78CW66&colid=28GSOAUQ6M2YF&psc=0&ref_=lv_ov_lig_dp_it

https://smile.amazon.com/dp/B0017WRH7O/?coliid=I20YTSJ8FILN4T&colid=28GSOAUQ6M2YF&psc=0&ref_=lv_ov_lig_dp_it

https://smile.amazon.com/dp/B01L0GABM4/?coliid=I1O8H1XG5FE5IR&colid=28GSOAUQ6M2YF&psc=0&ref_=lv_ov_lig_dp_it

And this one
https://smile.amazon.com/dp/B005VUBGZW/?coliid=I13HK88KRJTWNJ&colid=28GSOAUQ6M2YF&psc=1&ref_=lv_ov_lig_dp_it

MrM1 · April 2018

Here is the view ...

Image: https://us.v-cdn.net/6024911/uploads/editor/sl/sk2je19dyps0.jpg

Image: https://us.v-cdn.net/6024911/uploads/editor/pj/c3zj81b3tyva.jpg

Desert Rat · April 2018

Allow me to get this thread back on track, that is, bashing small wind power, one of my favorite pastimes.

The NREL 30 meter wind chart for your area shows an average annual wind speed of 4 m/s or less. That's around 9 mph, less than what is considered even barely adequate for a small wind generator. And here's the kicker: that is being measured at 30 meters off the ground, nearly 100 feet. Think about the expense and labor involved in erecting a 100 foot tower, not to mention how you're going to do maintenance. Not worth it.

Joesouth75 · May 2018

Ok Everyone, my 3000w inverter us an Aims Pure sine wave model. I have in my shed on the shelf a 2000w modified sine wave model. It was my understanding that modified does not run motors well. Is this correct?

Adding wind generator to solar array

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