PV Panels - General Questions. - Green Home Improvement - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Green Home Improvement


Thread Tools Display Modes
Old 02-16-2009, 07:20 AM   #1
I have gas!
Clutchcargo's Avatar
Join Date: Mar 2007
Location: Massachusetts
Posts: 1,975
Rewards Points: 1,374

PV panels - general questions.

I working on a cost/benefit analysis for PV panels.
Take a 24V-175W panel. Inverted, does this equate to 120V AC @ 35W? What about losses, how many watts do these panels actually produce at the receptacle?
Running the wires, do the run the wires inside the wall or down the outside of the house?
What is the lifespan of the batteries for storage?


I tear things down and build them up.

Last edited by Clutchcargo; 02-16-2009 at 07:24 AM.
Clutchcargo is offline   Reply With Quote
Old 02-16-2009, 09:27 AM   #2
the Musigician
DangerMouse's Avatar
Join Date: Jul 2008
Location: I'm right here!
Posts: 10,404
Rewards Points: 2,000

hey clutch! i had some of the same q's. check this thread out.
On the topic of 12V lighting.. DIY



[SIGPIC][/SIGPIC]Click here to see some of my original magic tricks and trick boxes!
DangerMouse is offline   Reply With Quote
Old 04-07-2009, 11:49 AM   #3
Join Date: Apr 2009
Posts: 34
Rewards Points: 25

I am by no means an expert but let me take a stab:

The power ratings for solar panels (in watts) reflect the power output of the panel under some sort of standard test condition (usually specified in the fine print). The wattage is the same regardless of the voltage. A 24V 175 watt panel with an inverter to step it up to 120V AC would provide 175 watts at 120V AC but with some caveats:

1. In general, the standard test conditions will not reflect the conditions you have at your site. You may see more or less peak output and the average output power over the course of the day will almost certainly be much less.
2. Your inverter will not be 100% efficient. The actual efficiency can vary quite a bit depending on load and other factors. 90% is typical for a well designed setup.

Wire requirements are driven by building codes. There are safety issues involved.

Most people use lead acid acid batteries for off grid systems. These last between 3 years and 10 years depending on the battery type and how well they are treated. They die much sooner if they experience unfavorable charge discharge cycling (running them dry is particularly bad). The more expensive types last longer.
flyboy is offline   Reply With Quote
Old 04-08-2009, 09:53 AM   #4
Join Date: Oct 2008
Location: Western Kentucky
Posts: 118
Rewards Points: 75

Flyboy pretty much nailed the tech part,
Now for some cost info, since the new tax credit the feds implemented this year we decided to do another impromptu cost for a friend in Wisconsin which is one of only a handful of states that offer rebates and incentives. An important note is that in order get any tax credits or rebates the equipment and installation must be installed and bought from certified sources.

12 - 200watt panels = $12,000 and assumes 12 kWh daily for 5 hours of average sun and is a fair estimate for most of the USA but your site needs to be evaluated first.
Grid tied inverter, charge controller and misc electronics = $3000, or if you want to be off grid then assume this to be the battery cost but there are no tax credits or rebates for pure off grid systems.
Misc mounting and accessories = $2000
Installation = $3000
Total = $20,000
Minus state rebate of 25% leaves $15,000
Minus poco rebate leaves $12,000
Minus Fed credit leaves $8,400
Cost of electricity produced monthly 360kWh = $36 @ 10 cent per kWh
Equals a 19 year payback

$10,000 in a 5% CD will net $41 a month in interest and you still have the ten grand.

Remember most states don't have those rebates. Mine has zero rebates.

EDIT: I just noticed MA only has an insolation of 4 hours so subtract 200 watts from all my math, the new payback would be 24 years but probably less because I think you pay more for power.

Last edited by hychesee; 04-08-2009 at 10:19 AM. Reason: watts
hychesee is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gas Pipe General Questions jamiedolan Plumbing 10 12-06-2012 10:46 AM
General questions about natural gas fittings darsunt HVAC 5 10-30-2008 04:39 PM
some random, general plant questions joeyboy Landscaping & Lawn Care 7 11-30-2007 06:34 PM
some questions on masonry/cement/concrete (general q's) joeyboy Building & Construction 20 06-25-2007 08:53 PM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1