Residential PV Solar Calculator

Try the attached Excel 2003 workbook to calculate the economics of installing a grid-tie PV solor system to your home. You can adjust most of the assumptions. The only assumption you cannot change is that all generated electricity is valued at the entered electricity price (either is consumed in home so avoids the purchase of electricity or is sold back to the utility at the same price - net metering).

Comments welcome to improve the calculator.

Return link: Residential PV Solar Information
NREL solar calculator: NREL solar calculator

Example Economics

+ Major Variables to Consider

Electricity Cost, cents/kWH (depends on location, supplier, type of billing)
Installed Cost of Panels, $/Watt (about 6-9 depending on supplier, contractor, self-installed)
Average Solar Radiation (kWH/Meter Sq./Day, depends on location)
Rebates/Tax Credits, k$ (depends on supplier, city, state, Federal Gov.)
Financing (term, interest rate, tax rate)
Supply Efficiency (%) (includes panels, converter, wiring)
Electricity Inflation Rate, %/Year (difficult to predict, but likely to be > 3%/Year)

+ Assumptions

Supply Efficiency: 64%
Electricity Inflation Rate: 4%/Year

_______________________________________________________________________

Payout in Years @ Electricity Cost = 25 cents/kWH

Panel Cost, $/Watt	6.0	6.0	8.0	8.0	10.0	10.0
Rebates/Tax Credits, k$	----	10.0	----	10.0	----	10.0
	Payout, Years
Solar Radiation = 6.5	11.9	7.2	14.9	10.9	17.8	14.0
Solar Radiation = 5.0	14.7	10.5	18.1	14.7	21.3	18.0

_______________________________________________________________________

Payout in Years @ Electricity Cost = 15 cents/kWH

Panel Cost, $/Watt	6.0	6.0	8.0	8.0	10.0	10.0
Rebates/Tax Credits, k$	----	10.0	----	10.0	0.0	10.0
	Payout, Years
Solar Radiation = 6.5	17.7	11.2	21.8	16.3	>25	20.6
Solar Radiation = 5.0	21.3	15.3	>25	21.2	>25	>25

_______________________________________________________________________

Tags: calculator, solar, solar calculator

Attachments:

DOE Residential Electricity Rates, Feb 2008.xls, 25 KB
Residential Solar Panel Economics Calculator.xls, 51 KB
us_pv_annual_may2004.jpg, 263 KB

▶ Reply to This

Replies to This Discussion

Permalink Reply by B. Barley on July 22, 2008 at 4:41am: I have a solar PV calculator that is made up in an Excel spreadsheet that will calculate all the formulas giving needed amount of battery supply & PV supply needed. This spreasheet is intended for off grid applications.
It's a fun tool to use as well for anybody wanting to learn how a PV system operates.

e-mail me at: capturedtime@yahoo.com if you'd like me to send you the file or leave me a comment
on my profile if you'd like it sent to you. ( free! ); ▶ Reply to This

Permalink Reply by Don Castella on August 7, 2008 at 1:34pm: I note that you use $.15/KWH and $.25/KWH in the charts above. When I tried using my actual electric rate today of $.08/KWH, I found the payout exceeded 25 years in my area.; ▶ Reply to This

Permalink Reply by Bruce Campbell on July 16, 2009 at 5:21am: I agreee, Don. From all my work, PV solar for residential use is not ready for prime time in most locations from a pure economic payback point of view. Hawaii is a great location since they get many days of high intensity sun, have the highest electricity costs in the U.S. and have provided significant subsidies for the installation of solar panels. Even with the 30% Federal subsidy available this year, at 12 cents/kwh where I live and no net metering program, I can't justify the investment. However, when I consider the money our federal government is currently wasting, I think they should have a program to put solar panels on as many schools as possible where certain criteria are met. Most schools aren't in session during the summer so a high percentage of the generated electricity could be sold so help fund the schools. This program would also help to slow the growth in property taxes and help develop a larger base to help the technology.; ▶ Reply to This

Permalink Reply by James R Kirst on September 9, 2008 at 1:08pm: Hi my name is jim and im interested in PV solar /i just sent an email to fetch the calculator .
Also Im interested in seeing just what is needed to do an on grid application any Ideas

rgds jim kirst; ▶ Reply to This

Permalink Reply by Jim cochrum on July 15, 2009 at 10:17am: I would like to take a look at the spreadsheet for off-grid applications.
Thank you,
Jim
jcochrum@gmail.com; ▶ Reply to This

Permalink Reply by B. Barley on June 18, 2009 at 3:37am: I have an easy off grid PV calculator that is fun play around with also at:
www.ogrecontrol.com; ▶ Reply to This