Solar panel voltage

Wal · Member

Solar panel voltage

dave06 · Guru

to acheive a voltage rating of that height you must be in full sun on a warmish day with a cold panel, the charging rate of solar panels will vary enormously throughout the day and it will show anywhere from 13.6v to 16v (regulated)

I think 16v constant may be a little excessive over a long period of time and if it is running at that or more for a prolonged period of time then I would have a concern about the regulator

I would check it when the battery was fully charged and see if the panel charge comes back to a more "nominal" voltage, if it doesnt then i wouldnt "borrow" it again, or I would see about getting another reg put on

I personally would go and grab a "briefcase" solar panel that gives about 80 watts, they cost about $1100, sometimes cheaper if you happen to catch a special

failing that I would start asking at specialist 12 volt shops for advice and possible replacement reg

just google "12 volt shop" and give them a ring, there will be one in your area somewhere and they are normally pretty good

-- Edited by dave06 on Thursday 30th of July 2009 11:37:31 AM

Peter_n_Margaret · Guru

16V seems high, but if the output of the panel is not too big and the regulator is doing its job, it will be OK.
What tye of battery is it?
What is the output (Amps or Watts) is the solar panel?
Do you have any information on the regulator?

Cheers,
Peter

Peter_n_Margaret · Guru

The unregulated output of most solar panels is between 16 and 20 volts.
These outpt voltages stay fairly constant but the current (amps/watts) will vary with sun intensity and angle.
This should also be marked on the back of the panel.

Cheers,
Peter

twobob · Guru

Testing my memory, but I do not believe any solar panel produces more than 14.8v, regulated or not.

What i think is that you have a 24volt setup panel, and the model number appears to support that view BP24.

This is achieved by connecting two panels in series, and there may not be any indication that it is indeed two panels.

Eitherway, charging at greater than 14v on a 12 v system is way outside the limitations of the battery.

To test to see if what i am saying is correct, put a resistor (any sort) across the output of the panels (not connected to anything else) and measure with the volt meter in full sun.

dave06 · Guru

I've done a "little" bit of poking around and the numbers that you have mentioned wombat (bp24) refers to a battery pack not to the voltage of the panel,

the bp246 is a "general" use portable solar panel with fully integrated voltage regulator, this unit is normally sold with electric fence setups and not usually available to the general public

it is an unusual one but I am sure a little bit more "digging around" will uncover it's secrets

normally on the back of bp's range of panels the numbers read something like "bp485" which by the way relates to an 85 watt solar panel

the 2 series of panels is more for ag use than domestic

Smokeydk · Guru

My solar panel is 80 watt.......the regulator cuts it off at 13.85 amps...full charged my 120 amp hour deep cycle battery

Solar panel is BP-8 80watt

Rated power: 80W
Typical applications: Suited to grid-connect applications such as residential systems or installations on commercial roofs, as well as traditional solar applications such as remote telecommunications. Ideal for caravan systems and camper-trailers.
Configuration: BP 380N - Universal frame, a sealed junction box with output cables and polarised multicontact connectors.
BP 380J - Universal frame with an accessible junction box for cable connection.
Nominal voltage: 12V
Cell technology: Multicrystalline
Dimensions: 1209 x 537 x 50mm
Weight: 7.7kg
Glass type: High transmission 3mm tempered glass.
Frame type: Clear anodised aluminium alloy type 6063T6. Colour: silver.
WARRANTY: 25 YEARS

Price - 899.00 AUD (inc. GST in Australia)

from http://www.homeof12volt.com/index.php/page/shop/index

Dave

The Gnome · Senior Member

thank you DAVE
Exakery the info i have been seeking

hammer · Senior Member

16 volts is far to high even if the battery is dead flat it should only charge at about 14.8 volts. I would think that the regulator is U/S
I would take it to Jaycar dealer or like and have it checked out.

dave06 · Guru

the 12 volt shop here in adelaide have regulaters for $80 odd bucks from memory, not too dear I figure

PeterD · Guru

You did not state exactly the construction of your battery so we can't give you the recommended charge or float voltage but being a sealed battery I would reckon that the charge voltage should not exceed 14.4 V.

No one has been able to identify your panels characteristics. We firstly have to identify the battery voltage it was meant to charge (if indeed it was designed to charge batteries, not all panels are.) Count the number of cells in it. A panel designed to charge a 12 V battery will have 36 cells. If it has double that, then it is designed for 24 V systems. If it has less it could have been designed to float (maintenance) charge a 12 V battery or be used in conjunction with a MPPT controller (Multi Point Power Tracking.) Another way to identify the panel is to remove the regulator and measure the open circuit voltage, it should be around 21 V for your application.

If the panel is a 26 cell one then your regulator is shot. Cease using it on your battery before you bugger it. Get yourself a new regulator. If the panel is anything else then get yourself an MPPT regulator and you can use your panel. However an MPPT regulator may cost about the same as a new 100 -120 W panel.

What are the physical dimensions, someone may be able to give you an approximate its power capabilities. If it is a 12 V charging panel you can disconnect the regulator, put an amp meter across the terminals and measure the short circuit current (you will not damage the panel.) Its rated power output will be around (or a little less than) the short circuit current multiplied by 17.

PeterD

Cruising Granny · Guru

Welcome to Nomads Hammer.
After all that battery speak, which was amazingly helpful, I thought someone should welcome you to this site.
Hope we hear more from you. Cheers Chris

Smokeydk · Guru

My solar panel is 80 watt.......the regulator cuts it off at 13.85 amps...full charged my 120 amp hour deep cycle battery

should read

My solar panel is 80 watt.......the regulator cuts it off at 13.85 Volts...full charged my 120 amp hour deep cycle battery

Dammm site wouldnt let Me edit it sorry

Dave

dave06 · Guru

Dave if you go into "more", just on the top right of your post, click on that and then click on "edit" you will find you are able to do it

that voltage (13.85) sounds "about" right to me, if it was feeding more than that in then I would replace the regulater, 16 volt sounds to me as if it is the "unregulated" output of the panel as stated by Peter

I would gather as many numbers off the unit as I possibly could and ask at the twelve volt shop, I tend to think this particular unit (and I am far from an expert on this) is designed for charging batterys for an electric fence or similar, my assumption is based on the small ammount of research that I did with the numbers provided

as far as I can tell the normal panels sold to everyday consumers start with BP4##

there is nothing wrong with using an "agricultural" one as the system running the fence is still based around a twelve volt sytem

I truly tend to think the regulater is shot, probably a ten cent diode or whatever is in there, (wombat would be able to tell you which one it was and what is in there)

Smokeydk · Guru

I did that Davo......but it told Me I didnt have permission to do it.....I think Wombat had that trouble recently...

Another thing .....recently I found I recharged the battery..only to find out when I ran a Volt meter over it....it said it was 12.6 volts....I've since been told...thats Ok....it will read correctly after couple hours rest...and when it is under load.....the instructions I got about my solar panel....unregulated it produces 22 Volts.....I agree with Davo....sounds like the regulator has died

Dave

dave06 · Guru

a volt meter is a "rough" idea of what the battery is actually holding, if you take a reading directly after charging even for an hour it will read "full" whereas it may only be partially charged, it is what is known in the industry as a "shallow" or " surface" charge

the only true way to read a battery's charge level is to check it a couple of hours after ANY charge has been placed in

yeah i had the same trouble a while ago when I went to edit a peice, it came good after a while, must have been a gremlin in the system

Wal · Member

Thank you all for your advice, I will complete the recommended tests and contact bp / 12 volt shop. I believe the general opinion of a non servicable regulator is correct. Thanks again
Wal

PeterD · Guru

dave06 wrote:
that voltage (13.85) sounds "about" right to me, if it was feeding more than that in then I would replace the regulater, 16 volt sounds to me as if it is the "unregulated" output of the panel as stated by Peter

There are 2 peters in this thread, the other said 16 V was too high and I said the OC (open circuit) voltage would be around 21 V.

If the OC voltage is 16 - 17 V then you have the style of panel that has less than 26 cells - these are designed for systems that are connected to the mains grid to feed power back into the grid. They are used in conjunction with an MPPT regulator. This style of panel is not suitable for use with a conventional regulator for charging batteries due to it having too low a voltage output. That is why I suggested counting the cells in it or measuring the OC voltage.

-- Edited by PeterD on Thursday 6th of August 2009 12:42:58 AM

dave06 · Guru

fully aware of who said what!

Wal · Member

Hi again, the panel is a BP 246 and has 32 cells. I can't find any info on the regulator.
The battery is a 120 amp fully sealed lead acid battery, made by supercharge.
Thanks
Wal

dave06 · Guru

grab a volt meter and take a reading directly off the output of the panels themselves before the regulater, if the reading is the same voltage as after the reg then you have found your problem

if it was me I would go and grab another regulater (about $80 - $90) from a "12 volt shop" or better still take the whole panel in to them and get them to test and repair, they may only charge you a small ammount to have a "fully functioning" solar panel

unless one knows EXACTLY what one is doing then one could end up with a "stuffed" panel, I use them but I dont dismantle them, leave that to the experts

PeterD · Guru

Wal wrote:

Hi again, the panel is a BP 246 and has 32 cells. I can't find any info on the regulator.
The battery is a 120 amp fully sealed lead acid battery, made by supercharge.
Thanks
Wal

Sorry to be the bearer of bad tidings. The standard panels for 12 V battery charging have 36 cells and a peak power voltage of around 17.5 V. Your panel will have a peak power voltage of around 15.5 V (17.5 / 36 * 32 = 15.555V) The voltage difference between your charging voltage and your panels maximum power output voltage is not sufficient to to give effective charging. Sure you will get some charging but nothing near what you would expect from a 36 cell panel. You will however be able to use your panel to its ful efficiency if you replace the regulator with an MPPT controller (Multi Power Point Tracking) In fact you will get more power from your panel with an MPPT controller than with a 36 cell panel using the usual series pass regulator.

As an aside - we used to use small power 32 cell panels without a regulator to give a maintenance float charge to diesel starting batteries. It was considered that the voltage output from a 32 cell panel was too low to bugger a battery.

twobob · Guru

Peter

While Dave and Wal are sorting things out, I have a couple of questions, that may help me understand solar better, and I hope you to be willing to discuss them

Solar cells produce 0.5 to 0.6 volts each, nominal 0.57V.
The delema is to get more amps out of them.
They can be arranged in series/parallel combinations, to overcome this failing

So, a 32 cell, 0.5v, can be 2*8volt units in series, ie 16volt
A 36 cell unit, can be 3*6volt units in series, ie 18volt

The more parallel cells in a series, the more current and thus power.

Is this consistant with your understanding?

This MPPT regulator you refer too, has me. Are you refering to a tracking system? for the panels, if not, what is it and how is it more efficent.

-- Edited by twobob on Wednesday 12th of August 2009 09:57:42 PM

PeterD · Guru

twobob wrote:

Peter

Solar cells produce 0.5 to 0.6 volts each, nominal 0.57V.
The delema is to get more amps out of them.
They can be arranged in series/parallel combinations, to overcome this failing

So, a 32 cell, 0.5v, can be 2*8volt units in series, ie 16volt
A 36 cell unit, can be 3*6volt units in series, ie 18volt

The more parallel cells in a series, the more current and thus power.

Is this consistant with your understanding?

I don't get the gist of your question. In both 32 & 36 cell panels all the cells are in series. For larger current (power) panels they simply use cells with a larger area.

For MPPT see this link

PeterD

-- Edited by PeterD on Thursday 13th of August 2009 12:44:45 AM

dave06 · Guru

yep and if you understand that gobbledygook then you should be working for N.A.S.A.

keep it simple, dont need to understand a simple system to repair it, get a new regulator and have a beer while it charges your battery, you dont need to know how it works only that it works

Smokeydk · Guru

I agree with you Davo....thinking to much gives me brain damage lol

Dave