Author Topic: Solar panel output  (Read 156 times)

Offline neilv

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Solar panel output
« on: January 09, 2020, 05:51:59 PM »
I have a Kick Arse 150w solar panel which I have used successfully for the past two years. I connect it to the Anderson plug on the Tvan which charges from the car when driving. On the panel I have the option to go through a regulator or not. I go through the regulator, as there is no other regulator between the panel and the batteries.
Last week I was testing another panel for a friend with a multimeter and knew that mine system was working correctly so tested mine to get a base line. It was a sunny clear day with the sun overhead around midday. I tested directly after the regulator and was surprised when the voltage was only 3.8V. I was expecting about 13-14 volts. I tested again before the regulator and got a reading of 20 volts. The Victron volt meter inside the van was running at 13.2V, which is normally near to where it runs.

The panel/battery system has been working fine for two years and we were camped for two weeks on this site running a fridge, lights and fans when needed without any issues and without any external power.

What voltage reading should I expect to see after the regulator?
Any other comments?
I am not terribly electrically minded so please keep the answers in layman's terms.
The Tvan is a 2011 Mk3.

Thanks for any assistance.

Neil & Lyn
2011 TVan Canning
2015 Prado GXL

Offline Frankrhona

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Re: Solar panel output
« Reply #1 on: January 09, 2020, 08:07:08 PM »
Just a quick thought. It sounds like atleast one of the squares on the solar panel may have been covered. I have had the same low voltage when I covered just one square (100 x 100mm), so I assume the panels are wired in series.
Cheers,
Andrew
Andrew & Clare
2005 ZD30 Patrol
2006 Canning Tvan

Offline neilv

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Re: Solar panel output
« Reply #2 on: January 10, 2020, 07:54:58 AM »
Thanks Frank, but none of the panel was covered. It was in open area with pure blue sky.
Neil & Lyn
2011 TVan Canning
2015 Prado GXL

Offline mal1958

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Re: Solar panel output
« Reply #3 on: January 10, 2020, 11:02:15 AM »
If the solar panel was connected to the battery via the regulator and the battery was reading 13 V, then the output of the regulator should also read 13 V.   If not then you have a wiring issue (high resistance) where you are losing voltage. 

If there was no battery connected to the solar panel and regulator, then the output of the regulator could read only 3 V on a multi meter.

It does depend on the type of regulator.    If the regulator is a PWM (Pulse Width Modulator), the regulator gives a pulse of the voltage from the solar panel for a short instant (on) and then gives nothing for a period of time (off), this cycle repeats.   The width and frequency of the pulses depends on the voltage on the output terminals of the regulator.     If there is no battery to charge, then the "off" time may be significantly longer than the "on" time with the result, the average may appear to be only 3V on a multi meter.

Offline Wetjala

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Re: Solar panel output
« Reply #4 on: January 10, 2020, 11:46:29 AM »
Was the regulator connected to a battery at the time of testing? If not then you will not see the charging voltage which should be > 13Vdc depending on battery type. For solar panel regulators (PWM or MPPT) to operate they need to be connected to a load battery in order to ascertain the charging stage (Bulk, Absorption or Float) required at that time for the battery. The connection to the battery not only provides regulated charge to the battery but also allows the controller to sense the voltage so as to properly regulate the charge profile (which on some chargers can be changed to suit the chemistry of the battery. Profiles on Victron MPPT solar charge controllers, for example, can be changed via bluetooth using an app on a phone). When the battery is first connected, the controller will enter the Bulk charge stage and depending on the charge state of the battery (measured voltage as per the profile) will either stay on bulk charge for a time or if the voltage is at the prescribed limit will step into the absorption stage (which can take a long time to complete depending on battery charge state) and then finally into the float stage.

If you did in fact have the battery connected to the controller at the time of testing then either the battery or the solar regulator is kaput! My guess is you didn't have the battery connected.

PS: I think you'll find it's "KickAss" rather than "Kick Arse" solar panels!  ;)
« Last Edit: January 10, 2020, 01:14:17 PM by Wetjala »