Thread: solar panel (help please)

Hi rangieman, the two bottom stats are the only ones you need to worry about.

VOLTS (VMP) 17.54 is the maximum operating voltage you can expect to get out of the panel when it’s connected to a load.

Likewise, AMPS (IMP) 1.80 is the maximum current (I) you can expect to get out of the panel when it’s connected to a load.

If you were just using one panel and being down south, you could get away with connecting it straight to the battery, no reg needed.

You didn’t say how many panels you have so it a bit hard to give you an idea of what you need.

Also, what are you planning to use them for.

Cheers.

Sorry i have two pannels and i thought i could use these to keep my aux battery topped up as all that will be running off the aux battery is a 39 lt engle fridge

this is so i dont have to run the car every day or 2 when camping

Should be no problem, just hook them up in parallel to your battery without a reg as long as you always have your fridge connected as well.

As you will be powering a fridge from the battery, the battery will not get to a point where the solar panels will over change the battery.

These solar panels are not large enough to fully recharge the battery while powering the fridge, but they should extend the amount of time you can power your fridge from the battery before you have to hook the battery up to the car.

Next, I don’t know that brand of solar panel but are the outputs marked as to which is positive and negative, plus the one thing you will need is a reversing diode. This will stop the solar panels draining your battery at night.

Anything else you need to know, just fire away.

Solar panels are great things to play with, especially when they are FREE, lucky you.

Cheers.

Just because your from down south doesn't meen you don't need a regulator, you will, as you will still be getting 22volts out of these things.
Jaycar have a 5amp one for about $20 or a 20amp one for around $40 or so, they work well. But you will still definately need one to reduce your incoming voltage.
Damien

Hi 6.5rangie, if rangieman was just going to use the panels to keep a battery charged when not in use then yes a reg would be needed.

As rangieman is going to have a load on the battery that is in excess of the output capacity of the panels then the battery will keep the voltage down bellow any level that would damage the battery.

BTW, the only way the solar panels can put out that high a voltage, is in an open circuit situation, in other words with no load.

The battery’s stats posted by rangieman states open circuit voltage is 12.21v (VOC)

I regularly charge batteries off an 80 watt solar panel with out a reg, it just means I keep an eye on the charge voltage.

Whether your battery is fully charged or not, measure the battery’s voltage and then connect the panels up to the battery, Panel positive to battery positive and panel negative to battery negative and then measure the voltage at the battery again.

There will be little increase in the battery voltage for quite some time as the battery itself acts as a reg because of the load it puts on the solar panels.

DO NOT use the panels to keep the battery charged when not in use without using a reg.

for the sake of a $20 regulator, wouldn't it be easier than keeping an eye on it and just let it run. What about when the fridge is not running and the battery is charged, i think if a reg was fitted you wouldn't have to worry about it.
The company i work for use to install those airtech units you see in service stations (automatic digital things that everyone can't figure out how to use) and a lot were solar powered, due to these having bugger all load and intermittent use we had to run a reg as not to burn out the LCD circuit board. but thats different to running a fridge i guess. it depends on what you want to run.

Hi again 6.5rangie, for $20 ( if they work ) it is worth it if rangieman needs to charge the battery up while not in use, but as he uses the car to charge the battery, it likely the solar panels will not be in use.

While using the panels to put some charge back into the battery while the battery is being used to power the fridge, the fridge is going to use more over a 24 hour period than two 30 watt panels will be able to replace in the few hours they are capable of putting power back into the battery.

BTW I’m not saying that a $20 reg won’t work but Jay Car do have a habit of marketing things that have a rather short operating life. Their dual battery charge controller is a perfect example.

If someone wants a solar panel reg, buy a good one and be done with it.

thanks guys some good info here i think ill still put a reg in and yes drive safe the panels have 3 terminals on the back 1 marked pos (+) and two others (one marked neg (-) the other is closer to the neg but no markings

the panels size are 520mm x 630

would a 5 amp reg be good enough
or a higher amp one