Posted by *Tim Thomson* on July 6, 2005, 1:00 pm

How many 15 watt/12 volt panels would it take to produce 300 k watts per

month?

How many batterries would be recommened for 300 k watts divided by 30 or

10 k watts a day? About five hours of sunlight per day.

Posted by *Steve Spence* on July 6, 2005, 3:08 pm

That would probably be 300 kWh / month.

the lower wattage panels are much more expensive per watt than those

100watts and up, but lets run the numbers.

Lets say that 300 kWh's / comes out to 10 kWh's per day, and that you do

have 5 full sun hours a day (are you in CA?).

10 kWh / 5h = 2 kW. You need a 2 kW array (round numbers not taking into

effect a 30% inefficiency fudge factor).

2 kW / 15 watt = 134 15w panels.

Steve Spence

Dir., Green Trust

http://www.green-trust.org

Contributing Editor

http://www.off-grid.net

http://www.rebelwolf.com/essn.html

Tim Thomson wrote:

*> How many 15 watt/12 volt panels would it take to produce 300 k watts per*

*> month?*

*> How many batterries would be recommened for 300 k watts divided by 30 or*

*> 10 k watts a day? About five hours of sunlight per day.*

*> *

Posted by *DJ* on July 6, 2005, 3:33 pm

Steve Spence wrote:

*> 10 kWh / 5h = 2 kW. You need a 2 kW array (round numbers not taking into*

*> effect a 30% inefficiency fudge factor).*

Two kilowatts is about the "rule of thumb" for a comfortable off grid

home, yep.

DJ

Posted by *Tim Thomson* on July 6, 2005, 7:11 pm

Steve Spence wrote:

*> That would probably be 300 kWh / month.*

*> the lower wattage panels are much more expensive per watt than those*

*> 100watts and up, but lets run the numbers.*

*> Lets say that 300 kWh's / comes out to 10 kWh's per day, and that you do*

*> have 5 full sun hours a day (are you in CA?).*

*> 10 kWh / 5h = 2 kW. You need a 2 kW array (round numbers not taking into*

*> effect a 30% inefficiency fudge factor).*

*> 2 kW / 15 watt = 134 15w panels.*

*> Steve Spence*

*> Dir., Green Trust*

*> http://www.green-trust.org *

*> Contributing Editor*

*> http://www.off-grid.net *

*> http://www.rebelwolf.com/essn.html *

*> Tim Thomson wrote:*

*> > How many 15 watt/12 volt panels would it take to produce 300 k watts per*

*> > month?*

*> > How many batterries would be recommened for 300 k watts divided by 30 or*

*> > 10 k watts a day? About five hours of sunlight per day.*

*> >*

I am not in CA. I am at 50 north by 115 west..... Crows Nest Pass Alberta

Canada.

I was just thinking about starting a small system. I have easy acsses to the

15 watt and now it looks like 30 watt panels.

I know they are pricey but I have been playing with 3-15 watt panels and was

just wondering. The 15 watt panels are about 20 inches by four feet, what size

are the 100 watt panels?

How many 12 volt batts does it take to store say 5 kva. I allready have an

inverter ( Brutus true sinewave 12 volt)

I could probably cut my needs in half by replacing my fridge with a natural

gas one if they make one that is. I could also get rid of the elctric dryer.

At present I am using the old incadesent lights. I still have a few wall warts

to get rid of etc..... I live in a wind belt, we have hundreds of those 3.2

mega watt wind turbines here but they will not allow a small one (400 watt) to

be installed at my house.

I am also looking at NG gas genney for back up.

Posted by *Steve Spence* on July 6, 2005, 7:30 pm

According to http://www.e-marine-inc.com/articles/images/canadaiso.jpg

you are looking at 2 full sun hours per day, not 5, so you will have to

at least double the number of panels. 5kva(h) of batteries might look

like 8 trojan t105's, 2 series x 4 parallel. That would give you 900ah,

or 450ah usable. You really need to rethink this.

Steve Spence

Dir., Green Trust, http://www.green-trust.org

Contributing Editor, http://www.off-grid.net

http://www.rebelwolf.com/essn.html

Tim Thomson wrote:

*> Steve Spence wrote:*

*> *

*> *

*>>That would probably be 300 kWh / month.*

*>>*

*>>the lower wattage panels are much more expensive per watt than those*

*>>100watts and up, but lets run the numbers.*

*>>*

*>>Lets say that 300 kWh's / comes out to 10 kWh's per day, and that you do*

*>>have 5 full sun hours a day (are you in CA?).*

*>>*

*>>10 kWh / 5h = 2 kW. You need a 2 kW array (round numbers not taking into*

*>>effect a 30% inefficiency fudge factor).*

*>>*

*>>2 kW / 15 watt = 134 15w panels.*

*>>*

*>>Steve Spence*

*>>Dir., Green Trust*

*>>http://www.green-trust.org *

*>>*

*>>Contributing Editor*

*>>http://www.off-grid.net *

*>>http://www.rebelwolf.com/essn.html *

*>>*

*>>Tim Thomson wrote:*

*>>*

*>>>How many 15 watt/12 volt panels would it take to produce 300 k watts per*

*>>>month?*

*>>>How many batterries would be recommened for 300 k watts divided by 30 or*

*>>>10 k watts a day? About five hours of sunlight per day.*

*>>>*

*> *

*> *

*> I am not in CA. I am at 50 north by 115 west..... Crows Nest Pass Alberta*

*> Canada.*

*> I was just thinking about starting a small system. I have easy acsses to the*

*> 15 watt and now it looks like 30 watt panels.*

*> I know they are pricey but I have been playing with 3-15 watt panels and was*

*> just wondering. The 15 watt panels are about 20 inches by four feet, what size*

*> are the 100 watt panels?*

*> *

*> How many 12 volt batts does it take to store say 5 kva. I allready have an*

*> inverter ( Brutus true sinewave 12 volt)*

*> I could probably cut my needs in half by replacing my fridge with a natural*

*> gas one if they make one that is. I could also get rid of the elctric dryer.*

*> At present I am using the old incadesent lights. I still have a few wall warts*

*> to get rid of etc..... I live in a wind belt, we have hundreds of those 3.2*

*> mega watt wind turbines here but they will not allow a small one (400 watt) to*

*> be installed at my house.*

*> I am also looking at NG gas genney for back up.*

*> *

> How many 15 watt/12 volt panels would it take to produce 300 k watts per> month?> How many batterries would be recommened for 300 k watts divided by 30 or> 10 k watts a day? About five hours of sunlight per day.>