Updated
4/20/15
John Drake Services, Inc.
1427 E. 68th Street
Long Beach, CA 90805
(562) 423-4879
electricity from the sun by John Drake II | home
About Us | About this website. | Getting Started | Solar Panels / Photovoltaic Modules - Read Before You Buy | Make A Plan | PV System Layout and Parts | Start with the loads you are going to operate | Battery Types and Sizing | Battery Safety | Battery Charging Voltages and Temperature | Battery Trouble Shooting | Charging Batteries - You can't have everything. | Battery State of Charge and Measurement | Safety Devices Fuses and Circuit Breakers | Series & Parallel Wiring | Wiring and Power Distribution Connections | Photovolatic Module Specifications - Real or a Pipe Dream | Photovoltaic module solar panel location and positioning | Photovoltaic Module and Solar Panel Information | Charge Controller Types | Wire and Cable Types | Wiring - Doing it Right | Connections for Wiring | Voltage Drop - Wire Loss, What are they? | Outdoor Connections | Wire loss - Voltage drop charts | D.C. to A.C. Inverters | Low Voltage D.C. Lighting & Color Temperature of Light | Battery System Monitoring | Dont fool yourself - Spending your money wisely. | Solar Converters GS-1AC | Linear Current Boosters for Water Pumping | Utility Grid Intertie Systems | Solar Insolation Chart | More Information | Alternative Energy Expectations | Power Needs Worksheet | Reference Sources | Contact Us
Photovolatic Module Specifications - Real or a Pipe Dream
First off, on this page I will refer to photovoltaic modules
as solar panels.
It's okay to humor the Old Guy once in a while.
Second off, we no longer sell solar panels so I don't have
an axe to grind and never did.
We receive many calls from people who have put a pv system
together and they are not getting the power out of the panels
that they expect.
"I have three 150 watt panels and at best I am getting around
380 watts out of them."
That does not sound out of line.
Back in 1989, when I went to the ARCO School, they took us
on a tour of their plant in Camarillo, California.
One stop was in their panel testing room.
It was painted flat black, was temperature controlled and had
a light source above the table tuned to daylight that would
subject the panel to the equivalent of 1000 watts per square
metre of insolation.
At that time the ratings on panels had two columns, one at 25
degrees C (77 degrees F) and the other at 45 degrees C
(113 degrees F).
There was a big difference between the two.
The 25 degree rating was basically used for selling the panel,
the 45 degree rating was pretty much for covering their backsides.
Remember, that as the cell temperature increases, the voltage
decreases.
But what if your panels never get above 77 degrees F and you still
don't get the rated output?
Most panels today show ratings at 1000 watts of solar insolation at
a given temperature as well as 800 watts of insolation.
Well, getting a solar insolaton of 1000 watts per square metre is very
problematic.
Right off the bat you can see that the ratings are good for
comparing panels, and for sizing the system components.
But don't go into a tizzy if your system does not produce name plate
power outputs.
Other contributing system factors are: the direction the panels are aimed,
their mounting angle, wire run length, wire sizes, connections and the
components in the system.
This page was not made up to discourage you, just to get you in an
educated position.
Knowledge is power.