Posted by *Ron Rosenfeld* on June 30, 2010, 10:30 am

On Tue, 29 Jun 2010 22:27:37 -0700, "Malcom \"Mal\" Reynolds"

*>I probably thought that in the original formula 4 hours was used and the total *

*>for the expression was divided by 4...4 hours being 1/6 it made more sense to *

*>divide the result by 6 than 4. Apparently I've been out of the loop too long*

*
and *
*>missed something in the formula.*

Let's review the formula and the definitions:

----------------------------------

so for 2.5A x 12V x 24h = 720 whr per day

dividing by the insolation factor of 4 = 180 Watts of PV panels.

--------------------------------

The OP requires a total of 720 wHr per day.

Insolation means the number of hours where you effectively get "full

sun" per day, sometimes also abbreviated ESH (effective sun hours),

and also the full rated output from your PV Panel.

Since the sun is not directly overhead all day, nine hours of daytime

will not generate the maximum out of the PV panels for the entire nine

hours; rather (in this case) it would be as if the sun were directly

overhead four hours. (The fact that this is 1/6 of a day is

irrelevant; the "day" could be any length).

Since the OP requires 720 wHr per day; and since there are 4 ESH per

day, you divide the 720 by four to determine how much Panel you

require.

Posted by *ABLE1* on June 30, 2010, 11:38 am

*> On Tue, 29 Jun 2010 22:27:37 -0700, "Malcom \"Mal\" Reynolds"*

*>>I probably thought that in the original formula 4 hours was used and the *

*>>total*

*>>for the expression was divided by 4...4 hours being 1/6 it made more sense *

*>>to*

*>>divide the result by 6 than 4. Apparently I've been out of the loop too *

*>>long and*

*>>missed something in the formula.*

*> Let's review the formula and the definitions:*

*> ----------------------------------*

*> so for 2.5A x 12V x 24h = 720 whr per day*

*> dividing by the insolation factor of 4 = 180 Watts of PV panels.*

*> --------------------------------*

*> The OP requires a total of 720 wHr per day.*

*> Insolation means the number of hours where you effectively get "full*

*> sun" per day, sometimes also abbreviated ESH (effective sun hours),*

*> and also the full rated output from your PV Panel.*

*> Since the sun is not directly overhead all day, nine hours of daytime*

*> will not generate the maximum out of the PV panels for the entire nine*

*> hours; rather (in this case) it would be as if the sun were directly*

*> overhead four hours. (The fact that this is 1/6 of a day is*

*> irrelevant; the "day" could be any length).*

*> Since the OP requires 720 wHr per day; and since there are 4 ESH per*

*> day, you divide the 720 by four to determine how much Panel you*

*> require.*

I (OP) have been reading the extra discussion here and really appreciate all

the comments. I understand now what is needed and will look into that

aspect. So, I say thanks!!!

My next question is a little different. Based upon what has been calculated

and putting together the necessary components. What would be a ballpark

price for such a system. I know that there may be a wide range based upon a

number of variables but am I looking at $00 or $0,000 to make it work.

Again thanks!!

Les

Posted by *Ron Rosenfeld* on June 30, 2010, 12:56 pm

On Wed, 30 Jun 2010 07:38:44 -0400, "ABLE1"

*>My next question is a little different. Based upon what has been calculated *

*>and putting together the necessary components. What would be a ballpark *

*>price for such a system. I know that there may be a wide range based upon a *

*>number of variables but am I looking at $00 or $0,000 to make it work.*

*>Again thanks!!*

*>Les*

It used to be that you could ballpark a figure of about $-$0/watt

installed power.

Figure that with losses accounted for you'll need maybe 250-275 watts

installed power in an off-grid system.

Since that figure, PV prices have gone down; battery prices have gone

up; and labor prices have probably gone up.

There may or may not be state or local subsidies available.

Posted by *Ron Rosenfeld* on June 30, 2010, 1:26 pm

wrote:

*>It used to be that you could ballpark a figure of about $-$0/watt*

*>installed power.*

*>Figure that with losses accounted for you'll need maybe 250-275 watts*

*>installed power in an off-grid system.*

*>Since that figure, PV prices have gone down; battery prices have gone*

*>up; and labor prices have probably gone up.*

*>There may or may not be state or local subsidies available.*

Those numbers are for professional installation.

If you do all the work yourself, you can cut the price considerably.

Posted by *Malcom \"Mal\" Reynolds* on June 30, 2010, 10:04 pm

*> Let's review the formula and the definitions:*

*> *

*> ----------------------------------*

*> so for 2.5A x 12V x 24h = 720 whr per day*

*> *

*> dividing by the insolation factor of 4 = 180 Watts of PV panels.*

*> --------------------------------*

*> *

*> The OP requires a total of 720 wHr per day.*

*> *

*> Insolation means the number of hours where you effectively get "full*

*> sun" per day, sometimes also abbreviated ESH (effective sun hours),*

*> and also the full rated output from your PV Panel.*

*> *

*> Since the sun is not directly overhead all day, nine hours of daytime*

*> will not generate the maximum out of the PV panels for the entire nine*

*> hours; rather (in this case) it would be as if the sun were directly*

*> overhead four hours. (The fact that this is 1/6 of a day is*

*> irrelevant; the "day" could be any length).*

*> *

*> Since the OP requires 720 wHr per day; and since there are 4 ESH per*

*> day, you divide the 720 by four to determine how much Panel you*

*> require.*

I understand what you are saying, but to me if there are "x" Effective Sun

Hours, "x" should replace 24h in the above formula, giving you how much panel

you require. Seems a little easier

--

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras lobortis volutpat

commodo. Morbi lobortis, massa fringilla adipiscing suscipit, velit urna

pharetra neque, non luctus arcu diam vitae justo. Vivamus lacinia scelerisque

ultricies. Nunc lobortis elit ligula. Aliquam sollicitudin nunc sed est gravida

ac viverra tellus ullamcorper. Vivamus non nisi suscipit nisi egestas venenatis.

Donec vitae arcu id urna euismod feugiat. Vivamus porta lobortis ultricies.

Nulla adipiscing tellus a neque vehicula porta. Maecenas volutpat aliquet

sagittis. Proin nisi magna, molestie id volutpat in, tincidunt sed dolor. Nullam

nisi erat, aliquet scelerisque sagittis vitae, pretium accumsan odio. Sed ut mi

iaculis eros rutrum tristique ut nec mi. Aliquam nec augue dui, in mattis urna.

In pretium metus eu diam blandit accumsan. Ut eu lorem sed odio porttitor

blandit.

>I probably thought that in the original formula 4 hours was used and the total>for the expression was divided by 4...4 hours being 1/6 it made more sense to>divide the result by 6 than 4. Apparently I've been out of the loop too long