Solar panel insolation measurements

First posted
Wednesday August 3, 2011 13:55
Monday August 15, 2011 17:06


Sunday August 14, 2011 Sundance calibrated solar panel covered.

Resistance checked with two meters.

Solar panels draw current when powered with a DC sources, we read.

If solar panels are used to charge batteries, then a diode must be used so as not to discharge the batteries when the solar panels output is less than the batteries, we also read.

k ohms

Hi Bill,

Stephanie was asked by me to send that email. We answer questions from customers all the time. However, we have never been recorded without our permission. That is what we had a problem with, not the fact that you were asking a question.

This is the description on Amazon:

This calibrated silicon solar cell is perfect for PV system installers, to test instruments or in the classroom. The factory has tested this 0.5volt, 2 x 4 cm cell in 1 sun conditions and written the output on the rear of the #2 size plastic case (2 1/4" x 1 3/8" for reference).Since a silicon cell is used, the current output is almost linear to the amount of light. Example: 1 sun = 250ma / 50% sun = 125ma.

I found this description of “1 sun” conditions:

The test condition 1 sun of AM1.5 represents the average situation for the U.S., but for some com­binations of locations and dates, this test con­dition may occur when the sun is too close to the horizon for making outdoor measurements. Given an AM of 1.5, testing outdoors may proceed only under a clear sky. A practical alternative is to perform PV measurements indoors using a solar simulator.

The factory we get these from, I believe uses a solar simulator for accuracy.

If you have other questions, feel free to contact me.



Ed Bender
President, Sundance Solar Products, Inc.
672 Currier Rd.
Hopkinton NH 03229
603-225-2020 v.
603-225-2022 f.

To: "SundanceSales"
Sent: Sunday, August 14, 2011 7:50:35 AM
Subject: Re: Verification of what I though I heard and additional question.

Hello Stephanie,

Please see draft email to Amazon.

Do we get answers?

Thanks in advance.


Sunday August 14, 2011 18:38

Hello Amazon, 

Calibrated solar panel was purchased through Amazon.

Product promptly arrived but did not contain any detailed documentation on use or how it was calibrated.

Only 267 ma and .58 volts was hand written on the back of the panel.

Our attempt to accurately report what was told to us appears to have annoyed Stephanie.

Stephanie wants to talk.

We want answers in writing to our questions to ensure accuracy of measurements made with Sundance claimed calibrated solar panel.

Please help us obtain written answers.

Thanks in advance,

Your customer,


From: "SundanceSales"
Sent: Friday, August 12, 2011 11:00:11 AM
Subject: RE: Verification of what I though I heard and additional question.

? Bill,

Please give us a call to discuss this. I seems that you recorded a phone conversation with one of our employees without our permission. If you would like some info that you can quote for your project, we'll be happy to speak with you, but not all of our employees are experts on all of our products, so please ask for Ed or Stephanie if you do call.

Please do not publish any recordings that you may already have made until speaking with us for authorization to do so.


Sales/Customer Support
Sundance Solar Products
672 Currier Rd
Hopkinton NH 03229
(603)225 2020
(603)225 2022 F

Tuesday August 8, 2011 12:34 

Video of Sundance calibrated solar cell raised and lowered to surface of 75 watt cfl on Tuesday August 9, 2011.

Audio for above video.

Phone conversation with Sundance solar on Tuesday August 9, 2011. Battery died so last portion of conversation informing me that only current was important in insolation determination was lost.

Athena Christodoulou of New Mexico Solar Energy Association introduced me to Mr Jeffery Granger on Tuesday July 26, 2011 at REI in Albuquerque.

Mr Granger is knowledgeable about photovoltaic energy efficiency measurements.
To give you a feeling for how much power the Sun provides, consider that on a sunny day, at solar noon, the sunlight at the surface of the Earth delivers about 1000 watts (one kilowatt) per square meter. A typical photovoltaic solar cell can convert about 15% of this to electricity, that is, about 150 watts (the best cells in the laboratory can go somewhat higher, up to about 34%, or 340 watts).

REI August 23, 2011 event scheduled

Friday August 5, 2011 it rained and is overcast. So 75 watt cfl

10.1 mv and 2.9 ma.

The efficiency of a solar cell.

Investment went South

Thursday August 4, 2011

Volts only using CEN-TECH auto ranging DVM.

Volts and amps.

Note model numbers on DVMs.

Setting the DVM to the right scale and turning on power before connecting the plus [red] lead is a good idea.

Audio clip 1

Audio clip 2

Audio clip 3

WARNING! Don't try short circulting alkaline, NiMH, NiCd, lithium, or lead-acid batteries.

By accident we short circuited a VW rabbit battery while trying to debug a fuel pump problem.

Insulation then wire melted.

Short circuiting output from voltage regulator is usually okay since most have short circuit protection, we also read. And tested.

High output impedance characteroze solar cells, we read, so short circuiting looks to be be safe
If we knew what we were doing, it would not be called research, would it?

Albert Einstein


Thursday August 4, 2011 06:15 

fast neutron
Santa Fe, NM
January 12, 2009

From actual experience, wind farms produce 1.2 watts per square meter. Solar Thermal and Photovoltaic methods capture 5 to 6 watts per square meter. There is no economy of size in either technology. Dividing the watts you need by those values gives the land area in square meters needed to produce the juice. The numbers are astronomical

From: "Jake Rudisill"
Sent: Tuesday, May 10, 2011 4:37:20 PM
Subject: Heat Rate misconception

Mr. Payne,

The definition of heat rate is not the heat content of just the fossil fuel inputting the conversion system—it is the conversion efficiency of the system with whatever is the heat input.

Every plant’s heat rate can thus be calculated.

Geothermal energy has a very high heat rate because it utilizes a relatively low grade of heat source—at its best, 350F, 100 psi steam, and thus 1200 btu/lbm. In a modern gas-fired boiler, steam is at 1000F and 2500 psi, with a much higher heat content of around 1770 btu/lbm.

heat rate

A measurement used in the energy industry to calculate how efficiently a generator uses heat energy. It is expressed as the number of BTUs of heat required to produce a kilowatt-hour of energy. Operators of generating facilities can make reasonably accurate estimates of the amount of heat energy a given quantity of any type of fuel, so when this is compared to the actual energy produced by the generator, the resulting figure tells how efficiently the generator converts that fuel into electrical energy.

Heat Rate (Energy Efficiency)

Overall thermal performance or energy efficiency for a power plant for a period can be defined as

fhr = H / E (1)


fhr = heat rate (Btu/kW, kJ/kW)

H = heat supplied to the power plant for a period (Btu, kJ)

E = energy output from the power plant in the period (kWh)

raised our curosity.

Arrived by USPS Wednesday August 3, 2011

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