Posted by *Ron Rosenfeld* on February 13, 2009, 2:35 pm

wrote:

*>Thanks for help...I have a 45 watt pv panel that charges a battery to*

*>power an LED night lite. I also have a small wind turbine. Neither of*

*>these are cost effective with local power rates at $.10(ish) per*

*>Kwh...*

*>I also have a 180 sq ft (17 sq m) solar air heater. I KNOW how much*

*>heat it produces and can convert btu's to kwh's....soooooo*

*>If at my location, panels at lat + 15 degs,... ave daily insolation is*

*>4..*

*>How may usable kwh could I expect from a typical 1 sq m pv panel? ..or*

*>how many usable kwh from a 17 sq m?*

*>Rob*

If you are converting from sq m to kWh/day, then just multiply by

efficiency of the panels (varies by make/model) and insolation:

kWh = Area * Eff * Insolation

Assuming panels with 14% efficiency:

kWh/day = 17 sq M *

14 % *

4 kWh/sq M /day

That would be the expected DC output from the panels, averaged over the

same period of time as the insolation figures.

--ron

Posted by *stevey* on February 14, 2009, 6:34 pm

*> wrote:*

*> >Thanks for help...I have a 45 watt pv panel that charges a battery to*

*> >power an LED night lite. I also have a small wind turbine. Neither of*

*> >these are cost effective with local power rates at $.10(ish) per*

*> >Kwh...*

*> >I also have a 180 sq ft (17 sq m) solar air heater. I KNOW how much*

*> >heat it produces and can convert btu's to kwh's....soooooo*

*> >If at my location, panels at lat + 15 degs,... ave daily insolation is*

*> >4..*

*> >How may usable kwh could I expect from a typical 1 sq m pv panel? ..or*

*> >how many usable kwh from a 17 sq m?*

*> >Rob*

*> If you are converting from sq m to kWh/day, then just multiply by*

*> efficiency of the panels (varies by make/model) and insolation:*

*> kWh = Area * Eff * Insolation*

*> Assuming panels with 14% efficiency:*

*> kWh/day = 17 sq M **

*> 14 % **

*> 4 kWh/sq M /day*

*> That would be the expected DC output from the panels, averaged over the*

*> same period of time as the insolation figures.*

*> --ron*

Ron's answer would be 9.52 KWh. If your heater works with DC power,

as with

your LED nightlight. You should not tilt your panel at Lat +15

degrees. You'll

lose much energy that way. A tilt of Lat - 15 should give you better

year-round

energy production.

-solarMD

Posted by *lemur* on February 14, 2009, 7:44 pm

Thanks Ron...thats what i was looking for

Steve...not trying to make electricity....im making heat and +15 deg

works MUCH better in winter...which is when we need it.

Rob

Posted by *Ron Rosenfeld* on February 15, 2009, 3:01 am

wrote:

*>Thanks Ron...thats what i was looking for*

*>Steve...not trying to make electricity....im making heat and +15 deg*

*>works MUCH better in winter...which is when we need it.*

*>Rob*

Rob,

One further comment. When you wrote

*> If at my location, panels at lat + 15 degs,... ave daily insolation is 4..*

I did make the assumption that the 4 hrs daily insolation was at +15°. If

that's not the case, the result will be different.

--ron

Posted by *Morris Dovey* on February 15, 2009, 3:17 am

lemur wrote:

*> Thanks Ron...thats what i was looking for*

*> *

*> Steve...not trying to make electricity....im making heat and +15 deg*

*> works MUCH better in winter...which is when we need it.*

If you're making heat where the ground is snow covered, then you may get

better results with vertical panels.

--

Morris Dovey

DeSoto Solar

DeSoto, Iowa USA

http://www.iedu.com/DeSoto/

>Thanks for help...I have a 45 watt pv panel that charges a battery to>power an LED night lite. I also have a small wind turbine. Neither of>these are cost effective with local power rates at $.10(ish) per>Kwh...>I also have a 180 sq ft (17 sq m) solar air heater. I KNOW how much>heat it produces and can convert btu's to kwh's....soooooo>If at my location, panels at lat + 15 degs,... ave daily insolation is>4..>How may usable kwh could I expect from a typical 1 sq m pv panel? ..or>how many usable kwh from a 17 sq m?>Rob