I've just bought three solar panels for my motorhome. They are rated at 17/18w.I've also bought a 6amp(60w) regulator. They are to charge two 110ah batteries.

Question 1: Do I wire the solar panels in series or in parallel? At the moment I've got them wired in parallel.

Question 2: When I put a cicuit tester on it to see what's what, I was getting 17v going into the regulator but only 9.8v going out to the batteries. So, will this fully charge my two big batteries? Surely it should output something like 13v shouldn't it?

Question 3: I've read advisories saying don't have it wired up while the engine is running,would that be such a bad thing? I am toying with the idea of putting in a blocking diode between the regulator and the batteries. Would this prevent any possible damage to the regulator and solar panels, and do away with the need to disconnect before running the engine?

 

for parallel panels i would seperate them from each other with diodes. this will prevent one panel from feeding into the other. what is the panel voltage rating?

what was the battery voltage before you hooked them up to the regulator? do you have a part # for this regulator?

 

Here is a good tutorial on solar energy. http://www.geology.wisc.edu/geo411/rademacher.html
http://www.freesunpower.com/


Don't use just any diodes. Use schottky barrier diodes. They are widely available.
http://www.ecodirect.com/Schottky-Solar-BD-p/schottky-solar-bd.htm

 

My post just went Poof, so I'll just give you solar panel plot to show relationship of voltage/current and power. V scale will be close to yours, & current from graph X 13 close to yours. Max. power as shown is around 13V. A voltage regulator should supply V boost , when needed, to keep panels operating near max output & charging V as needed by battery state of charge, dropping down to float at full charge.

 

That's a poor way to advertise your product.

Do you think that someone using solar panels and regulator in his MOTOR-home will buy your solar street lights? Or are you just spamming every thread with "solar" in the title??

edit; (my post above now makes no sense as the spammer's post was removed)

 

He went dark.

 

I was recently give a Solar Regulator that had been thrown out; its made by
Go Power! Electric Inc.
Doing a quick check I determined that the possible reason it had been tossed
is it had a short across the Solar inputs ... not knowing how these
regulators work I decided to do a bit of reverse engineering. To my dismay
it appears that this device shorts the solar panel out when the battery is
deemed fully charged. Because they also have a pair of blocking diodes this
would certainly stop the charging however I wonder if this is potentially
damaging to the solar panel.

Attempting to find an answer to that by reading specifications on PV panels;
most specs give a short cct current, and an open cct voltage and specify
that the operational voltage/current is somewhere in the middle of that.
Being that they provide a Short cct spec sort of implies they can be
shorted.

To make a long question short;

I am trying to understand;
A) Why shorting a panel is an acceptible way to shut off the charging
B) Is there a Solar Cell Equivalent CCT (similar to a battery) that can be
used to mathematically predict the characteristics of the cell.
C) Why shorting out a cell doesn't fry the cell

bxdobs wrote:
> I was recently give a Solar Regulator that had been thrown out; its made by
> Go Power! Electric Inc.
> Doing a quick check I determined that the possible reason it had been tossed
> is it had a short across the Solar inputs ... not knowing how these
> regulators work I decided to do a bit of reverse engineering. To my dismay
> it appears that this device shorts the solar panel out when the battery is
> deemed fully charged. Because they also have a pair of blocking diodes this
> would certainly stop the charging however I wonder if this is potentially
> damaging to the solar panel.



I think it is no problem. It just adds a tiny temperature
rise to the silicon.
> Attempting to find an answer to that by reading specifications on PV panels;
> most specs give a short cct current, and an open cct voltage and specify
> that the operational voltage/current is somewhere in the middle of that.
> Being that they provide a Short cct spec sort of implies they can be
> shorted.
> To make a long question short;

> I am trying to understand;
> A) Why shorting a panel is an acceptible way to shut off the charging



Since the panel is completely power limited, it is cheap and
reliable.
> B) Is there a Solar Cell Equivalent CCT (similar to a battery) that can be
> used to mathematically predict the characteristics of the cell.


A current source proportional to light intensity in parallel
with a string of silicon diode junctions. Instead of doing
this, mathematically, I suggest you simulate it with
LTspice, a free circuit simulator. It has built in
functions to display voltage, current and power dissipation.
http://www.linear.com/designtools/software/switchercad.jsp
Count the number of cells in series in your panel and use
that number of diodes. Set the current source to the panel
short circuit current rating.
> C) Why shorting out a cell doesn't fry the cell


They are so inefficient that the electric energy is only a
small part of the total heating caused by the absorbed
light. If you want to eliminate that small additional
heating, you could add a power resistor in series with the
short that drops just enough voltage to keep the blocking
diode from conducting. That will move that extra power to
the resistor. A better way might be to have that resistor
be the heating element in a water heater, so that you would
make some use of the energy.

 

I was recently give a Solar Regulator that had been thrown out; its made by
Go Power! Electric Inc.
Doing a quick check I determined that the possible reason it had been tossed
is it had a short across the Solar inputs ... not knowing how these
regulators work I decided to do a bit of reverse engineering. To my dismay
it appears that this device shorts the solar panel out when the battery is
deemed fully charged. Because they also have a pair of blocking diodes this
would certainly stop the charging however I wonder if this is potentially
damaging to the solar panel.

Attempting to find an answer to that by reading specifications on PV panels;
most specs give a short cct current, and an open cct voltage and specify
that the operational voltage/current is somewhere in the middle of that.
Being that they provide a Short cct spec sort of implies they can be
shorted.

To make a long question short;

I am trying to understand;
A) Why shorting a panel is an acceptible way to shut off the charging
ANSWER: ITS NOT
B) Is there a Solar Cell Equivalent CCT (similar to a battery) that can be
used to mathematically predict the characteristics of the cell.
C) Why shorting out a cell doesn't fry the cell
ANSWER: THEY ARE INHERENTLY CURRENT LIMITED. HOWEVER, THIS MIGHT DAMAGE THE CHEMISTRY OVER TIME AND PERFORMANCE DEGRADATION IS LIKELY

a silicon diode(s) in series (between panel and battery) will let the panel get to about 0.7v (x # of diodes) of the bat before charging current stops, i would add a resistor to limit the current if needed, etc. thats as cheap as i would go for a charging circuit. a real controller is better, etc.

bxdobs wrote:
> I was recently give a Solar Regulator that had been thrown out; its made by
> Go Power! Electric Inc.
> Doing a quick check I determined that the possible reason it had been tossed
> is it had a short across the Solar inputs ... not knowing how these
> regulators work I decided to do a bit of reverse engineering. To my dismay
> it appears that this device shorts the solar panel out when the battery is
> deemed fully charged. Because they also have a pair of blocking diodes this
> would certainly stop the charging however I wonder if this is potentially
> damaging to the solar panel.



I think it is no problem. It just adds a tiny temperature
rise to the silicon.
> Attempting to find an answer to that by reading specifications on PV panels;
> most specs give a short cct current, and an open cct voltage and specify
> that the operational voltage/current is somewhere in the middle of that.
> Being that they provide a Short cct spec sort of implies they can be
> shorted.
> To make a long question short;

> I am trying to understand;
> A) Why shorting a panel is an acceptible way to shut off the charging



Since the panel is completely power limited, it is cheap and
reliable.
> B) Is there a Solar Cell Equivalent CCT (similar to a battery) that can be
> used to mathematically predict the characteristics of the cell.


A current source proportional to light intensity in parallel
with a string of silicon diode junctions. Instead of doing
this, mathematically, I suggest you simulate it with
LTspice, a free circuit simulator. It has built in
functions to display voltage, current and power dissipation.
http://www.linear.com/designtools/software/switchercad.jsp
Count the number of cells in series in your panel and use
that number of diodes. Set the current source to the panel
short circuit current rating.
> C) Why shorting out a cell doesn't fry the cell


They are so inefficient that the electric energy is only a
small part of the total heating caused by the absorbed
light. If you want to eliminate that small additional
heating, you could add a power resistor in series with the
short that drops just enough voltage to keep the blocking
diode from conducting. That will move that extra power to
the resistor. A better way might be to have that resistor
be the heating element in a water heater, so that you would
make some use of the energy.

my answers in red

 

Hi,

Individual cells are wired in series strings to increase the module's voltage and the series strings are wired in parallel to increase the module's current. The back of the module is protected by another sheet of tempered glass or a long lasting material such as Tedlar.

The series parallel connections are passed through the protective backing and then wired to a weather proof junction box which is permanently mounted to the back of the module. The junction box is where the module's output connections are made.

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