Need some help starting my solar panels

Alsayyed

Hello friends I am new to this forum and needs help very badly.
You do not know how much happy I am to find this forum because I ma in real trouble with the solar panels. I am woodworker I mill some wood for personnel use and have 20 feet container I store my wood for air drying and this require hot air going through. I have installed 30 watt solar cell and other Siemens solar cell but do not know what the rating is but it looks like about 50 watts. I have two batteries 12v 100amp + 66 amp battery including 12v 1000watt inverter. My load is regular swinging fan do not know how many watts that consumes.\
The problem is the fan works for almost 1 hour then voltage drops down to 11 v on my charge control.
Know how can keep the fan running for almost 8 hours without getting alarm from the inverter. I need some help.

BB.

Re: Need some help starting my solar panels

If you get heavely into conservation and solar, you might want to get a kill-a-watt meter to measure your 120 VAC loads...

But, we can do some estimates here...

Lets assume that you have 30+50=80 watts of solar cells and you have a reasonably sunny climate.

Roughly, you are generating about 160 watts of power per day for use by your 120 VAC appliances (for now, just believe that the real ratings of the panels, efficiency of the charge controller, efficiency of charging the battery, and inverting your 12 VDC to 120 VAC gives you, very roughly, a rating of 2 hours of sun on your panels or 2 H * 80 Watts = 160 Watt*Hours).

You said that you don't know the rating of your fan, but from working backwards, your fan should be 160WH/1H~160watts.

There are several ways of approaching the problem. First is to simply through more solar panels at the job... In this case, at least, 8x more than you have now.

Also, you did not say how large your storage battery is, but you may also need a larger battery (or several smaller ones) to supply 8 hours of fan power.

The other method is to first find the most efficient method of moving your air (perhaps a few smaller DC computer type fans), get rid of the inverter (which, depending on model, probably wastes 15-30% or so of your energy).

The real problem here is that mechanical motion is really quite "expensive" in terms of using electricity. If you could use natural ventilation techniques (like a chimney, paint the storage building black to warm it up to get air circulation, use a Wind Turbine type ventilator on top of the building, etc.), you probably would get as good (or better) performance for much less cost, vs just throwing more solar panels and batteries at the problem.

There is a thread or two here on attic ventilation and one person installed solar powered attic fans (you can sometimes even get them from Home Depot type stores--but they are not cheap--and they only run when the sun is out). The new fan and larger venting worked well--so well in fact, that several years later, when the fan motor failed, that the attic was still nice and cool simply because of the extra venting created when the large solar fan was installed.

Also, besides painting the building black to absorb heat, there are many home made solar hot air heaters that work quite well for the application. You could build a glass wall (one person even used corrugated fiberglass) on the side of the container and pump hot air into the top of the container to help drying (plus additional venting/stirring, as needed).

I will stop here--because I don't know where you wish to go from here. Hope it helps.

-Bill

PS: Here is a link that describes a roof mounted Wind Turbine ventilator in case the US term is not familiar to you...

Also, if you are interested in air exchange with the outside, the area of the outlet vents need to be at least as large, or larger, than your inlet vents to get the optimum air exchange (air expands as it gets hot).

Lastly, I should also add, in Qatar you may not use 120 VAC @ 60--you can take a current meter (Digital Multi-Meter--DMM/DVM/etc.) and measure the current used by your inverter+fan combination (Power=Volts*Amps=Watts). But, be careful, your inverter may be drawing 15-20 amps and your standard DMM only goes up to 10 amps before it will blow a fuse.

Alsayyed

Re: Need some help starting my solar panels

Thank Bill that is very nice of you to pass me information and it was helpful for a new bee like more. First of all the voltage I am using is 220 v. I have set timer for the fan to start at certain time and shuts off at certain time. The battery I am using is just regular car battery.
I was surprised to learn that in order to keep this thing running I need at least 8 pieces these going to be a lot of money, for me is not good investment.
I was experimenting with the solar panels I have thought this will do the job easily. I might borrow from the scientic club another two and see if it is going to make a difference or not.
One more question Bill I have connected all the + together and the – together is right of I am doing something wrong.
By the way Bill the sun here is very hot and bright all day long.

mike95490

Re: Need some help starting my solar panels

You might be better off with solar hot air, and a small fan, as you've found, solar electric for a large fan is going to get expensive.
How does the wood react to hot air daytime, and cold at night, will that warp it ?

Alsayyed

Re: Need some help starting my solar panels

well Mike I do not know what to do. the place where i dry wood has no electricty becuase it is only small lot and surwonded with wall form four direction. in order to get electricity you have to build a 3 rooms at least. Beside if no air circulating the wood tend to cracks at end then what ever I store I have to throw a way, beside we do not have much tree in Qatar like you have in US. Even if I take the wood in the shade it will cracks too.

mike95490

Re: Need some help starting my solar panels

What causes wood to crack?
Are these logs (no bark) sawn wood boards ?? Does drying too fast cause cracks? I'm not really sure I can can help with that. Maybe the wood likes slow, controlled drying?

We can tell you how to get a fan to run, but the rest is up to you, how do you want it to run?

BB.

Re: Need some help starting my solar panels

Alsayyed,

Part of the problem is that both the 220 VAC fan and the inverter, and even the lamp timer (I assume) take power from the battery--and simple car battery will go flat in no time, even with a relatively small load (an roughl estimate for a car sized storage battery would be 2 amps (2a*12v=24 watts) 24 hours per day would be all you could expect...

And it needs to be a deep cycle storage battery, not just a car battery. A storage battery is designed for 50% (or even more) discharge (thicker lead plates, etc.). A car battery is designed to be "light" and have high starting current, and a maximum of 20% discharge (more, thinner plates).

Or, for 8 hours per day, it would be about 6amps (72 watts * 8 hours = 576 Watt*Hours per day)) would be the maximum power from one car battery.

Solar panels, you would want, roughly ~100 to 150 watts of panels to supply a 72 watt load. That could be a couple of 12 vdc computer fans scattered around the storage area. But, a large AC fan with inverter and timer--it would have to be a large system...

I am not sure what you question is... "...I have connected all the + together and the – together...". If your system is running (and not smoking), it sounds like you have the basic connection right.

However, it can get much more complicated to make a reliable system that does not quickly ruin batteries and smoke your connected equipment... It sounds like you have a charge controller and Low Voltage Disconnect. So, assuming that is all connected and working correctly, it sounds like you have a stable beginning system.

Wind-Sun has quite a bit of information (FAQs--Frequently Asked Questions) in the subsections (like Batteries).

But, just the other day, I ran across a Kyocera Solar information website and there is a Catalog (right click save, 3MB pdf download) which seems to be a great source of Solar information... From site planing to installation... Not bad for a free PDF download. It may have more information that you will need... If so, just ask more questions here.

Regarding your needs, it sounds like you may need internal air circulation more than air exchange with the outside? If so, there may be little you can do other than trying to find very efficient DC fans and connecting solar panels to them.

If, you can live with the fans only turning when the sun is shining, you can just connect a panel to the appropriate sized DC fan motor (saves a solar charge controller, batteries, and inverters).

It does get a bit tricky, because electronic fan motors (brush-less DC fan motors) are sensitive to their input voltage--and solar panels tend to output variable and "non-standard" voltages (a "12 volt panel may output between 17 and 23 VDC depending on temperature and loads--usually higher than a 12 volt dc fan can withstand).

I looked around before, and found that some 24 volt fans looked like they may run OK on 12 VDC solar panels. If you can find some 24 VDC brush-less computer fans in your area--I would give them a shot.

If you need the fans to run when it is dark, you will need batteries... But then adding a charge controller with 12 VDC computer fans would not be a bad option either... There are some programmable 12 VDC timers that you should be able to find locally that would work.

-Bill

System2

Re: Need some help starting my solar panels

Here's a link to some 12/24V ceiling fans: http://store.altenergystore.com/Lighting-Fans/Ceiling-Fans-DC/c509/ I have no experience with them but the info states that you can run them directly off a 10 to 20 watt panel. This would remove the inverter, battery and charge controller requirement and their inefficiencies. Maybe a couple of them mounted on the ceiling with your existing panels will work for you.


Cheers,

Bad Apple