Need some help starting my solar panels

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.