New guy needs your suggestions

System

Hi, first I gotta say I like this site, and I've learned a lot from you guys.
I'm pretty new to this solar and wind, I will make it short, 1st, My Battery bank is 2964 Amp-Hour, I got 245 watt PV, and a homemade wind turbine made from 2 back to back Ametek 38 volt motors, our wind here in San Antonio, Texas is about 7 MPH in a normal day turbine will generate about 6 -12 volts My battery bank is connected to 3000 watt inverter, that I have 1 computer + fax machine (100 watts ) which is on 10 hours a day, and a small TV, 40 watt, is on about 4 hours a day.
My wind turbine is connected direct to battery bank, PV’s are connected with a Xantrex C60 charge controller to the bank. I have diodes in positive lines of PV’s and wind turbine.
Now my problem, Looks like it that I don’t have enough charging power for everyday use. What do I do wrong?

All suggestions are welcome
I got pictures too if would help
Thanks in advance

icarus

Re: New guy needs your suggestions

In short, as we say do the math,,,(I'm sure Bill will update,,,)

Your 240 watts of panels, assuming IDEAL conditions will put out (net) ~750 watt/hours per day. (240x5 hoursX60 net ef) I am assuming for the moment that the wind contributes nothing. Putting out ~6-12 volts doesn't mean much unless you give an amperage and a time frame.

You loads, using your numbers are ~1.4kw hours,, so you can see that you are generating only ~50% of what you are using. Even the biggest battery bank in the world will run down in that situation. Long and short you either need more generating capacity, or smaller loads, or a combination of both. We have ~ 200 watts of panel, and use about 500wh/day. This gives us about a 3 day reserve before our batteries drop below 80% soc.

Tony

Cariboocoot

Re: New guy needs your suggestions

2964 amp/hrs of battery would want a charging rate of at least 148 amps. That's a lot of battery and a lot of charge. You'd need nearly 3000 watts in panels to provide that at 12 volts. Also, it's crackers to try and come anyplace near that rate on a 12 volt system.
I suggest you re-work your system starting with calculating your usage requirements. 100 watts for the computer seems low: mine runs anywhere from 90 to 190, depending on what it's doing. Anyway, 100 watts * 10 hours is 1000 watt/hrs. 40 watt TV * 4 hours is 160 watt/hrs. That's 1160 watt/hrs per day. In a 12 volt system that's only 96 amp/hrs. THESE CALCULATIONS DO NOT INCLUDE INEFFICIENCY LOSSES!
But basically, if your numbers are right you'd only need about 200 amp/hrs worth of battery to see you through a day (discharged to 50% maximum). Your 245 watt PV array should be able to charge that much, even without the wind generator.
Try disconnecting a few of those batteries and see what happens. (You should test them all too; some may have given up through lack of charging.)

icarus

Re: New guy needs your suggestions

I agree with CC about the size of the battery vs the size of the PV, I disagree that the panel is big enough to power you loads.

240 watts of panel for 6 hours will give you a gross of 1440 watt/hours
But by the time you put that into the battery and take it out and invert it in rough number you will get ~60% or ~860 wh/day. As I noted before (edited the bad math!) you use ~1160 wh/day, so you start out way in the hole,,,even on a perfect day.

I also don't consider drawing a battery down to 50% soc/dod to be a good practice. While the battery manufactures rate the number of discharge cycle using 50% dod I have always been more comfortable using 20% discharge rate.

In any case, clearly you have too much battery, not enough PV and too big of loads for the Pv you do have. I also agree with CC that fully charging and equalizing your battery asap is essential if you expect to save them.

Tony

System2

Re: New guy needs your suggestions

I also posted something in my own thread about a reference to array size to battery bank..I never knew that the bigger the bank the bigger the array needs to be...

thanks!

Cariboocoot

Re: New guy needs your suggestions

And I agree with Icarus on all points!
That panel would only work for a 1.2 kWhr load on a really sunny day in June with perfect panel exposure.
So to recap:

1). Check your actual usage with a kill-o-watt meter, and don't forget that inverters use power themselves: could be 25 watts over 24 hours; another 0.6 kW
2). Size the battery bank to suit the usage. 50% discharge is a maximum draw-down. For preference, amp/hr capacity should be 3-4 times usage.
3). Make sure you've got enough array to produce sufficient charging of the batteries. Typically, panels only average about 70% of their rated wattage over the course of a good day. How many hours of sunlight you get and how much of it actually hits the panels is highly dependant on your locale.

And remember: it may be good enough for now, but you'll always want more power in the future.

niel

Re: New guy needs your suggestions

thx1138 wrote: »

I also posted something in my own thread about a reference to array size to battery bank..I never knew that the bigger the bank the bigger the array needs to be...

thanks!

yes, that is to keep with the minimum charging parameters required by the batteries. although sometimes it is warranted to go outside of the range, we generally specify not to go outside the rate of 5-13% of the 20hr ah battery capacity. too low of a charge could deplete the battery of its needed charge allowing sulphation to set in and take away battery life and on the other hand we don't advise over 13% because of extra maintenance and possibly going against the recommendations of some manufacturers. some batteries do take higher percentages quite well, such as agms, but can still vary by manufacturer's recommendations.

System2

Re: New guy needs your suggestions

Thanks for the all the answers, now how about if I replace my Ametek generator with "windblue DC-540" with 6 feet blades, on the same 34 feet tower, does anyone has any experience on that one?

btw I'm using Kill-A-Watt

mike95490

Re: New guy needs your suggestions

Wind is going to be a dead end road, I'm afraid. Unless you have a fantastic location, a 500W genset, typically only puts out 20W in slow winds, if even that much. look for their power graph, in the 7MPH area.

System2

Re: New guy needs your suggestions

I just have replaced the blades with 3 skiny Aluminium blades, a lot faster now, and also I was thinking since my turbine is made from 2 Ameteks in series ,how about, change it to parallel, what do you guys think?
here is the pics before and after the blades
before
After new blades

mike95490

Re: New guy needs your suggestions

Only way to tell is to MEASURE how much power it puts out for a week, in config 1, and then a week in config 2.

Mount the Ameteks in the easier manner you can, series, parallel, it's actually all the same to the turbine. If you WIRE them in series, you will get higher voltage at lower speeds, which is generally a good thing, up to the limits of your insulation and rectifiers.

And see here about placing rotors in series
http://www.speakerfactory.net/wind_old.htm
http://www.selsam.com/
http://www.speakerfactory.net/TURBINES/INNOVATIONS/7ROT-7FOOT-2GEN/PAGES/7ROT-7FOOT-2GEN.html
Lots of ideas there, I like the mooring buoy, and it's U joint !