Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Fried Solar Panel?
I have a PWM controller.  If the battery voltage is below 14.whatever It is in bulk mode, the transistor switch is on.  When the battery gets up to the constant voltage level, absorption, boost, or whatever you call it, the transistor switch gets turned off and on repeatedly to keep the voltage at the constant voltage level.  If the controller is connected to the system including the roof fan, phone charger, and led lights and the battery lead gets disconnected the panel full 20 volts gets applied to all the stuff.  If there is enough stuff connected to keep the circuit loaded the voltage doesn't go too high.  Otherwise, the voltage goes too high.  The fancy ten speed controller for the fan can poof with enough volts.  Once the loads are all dispatched to the great beyond and no longer keeping the voltage down the controller itself can go poof.

If the engine is running and the alternator is alternating and all the  vehicle electronics are turned on the same thing can happen when the battery is disconnected.  The alternator output spikes and with no battery load all kinds of bad things happen.  Usually alternator diodes roast and lots of electronics need to be replaced.  

In both cases the systems could be designed to operate without the battery.  It would take more circuitry to do the voltage regulation to have it work with the battery missing.  It could be done but it would make it more expensive, less profit, and of very little additional value to the consumer. 

An MPPT controller does what a PWM controller plus it reduces the voltage, increasing the current.  That requires a circuit into which the current can flow.  Without that current flow the voltage will rise.  It will have similar but more expensive results. 

This spring, February 2017 as I recall, there was a thread on the reddit vandwellers forum about a solar failure.  It was in England so there wasn't much sun during winter.  As the spring brought more sun the 300 watt panel blew the 7.5 amp fuse between the controller and the battery.  It destroyed the MPPT controller.  It really can happen.  Yes, the fuse size was terribly wrong.  It was the fault of the idiot who installed it.
Add Thank You Reply
(07-17-2017, 11:46 AM)Weight Wrote: The sequence of connecting panels to controller to battery. I have tried to research this. The problem is the danger of shock from solar panels. Not that any damage will be done to any component. If there is any other information I would like to read more.

From my Morningstar TriStar manual:
• Never allow the solar array to be connected to the TriStar with the battery
disconnected. This can be a dangerous condition with high open-circuit solar voltages present at the terminals.

I think this is written for high voltage stationary systems.  With the small 12V, 24V or 36V mobile systems this should not be a problem, but IMO it is still good practice.

As to danger of shock, from IEC 60950-1:
0.2.1 Electric shock
Steady state voltages up to 42.4 V peak, or 60 VDC are not generally regarded as hazardous under dry conditions for an area of contact equivalent to a human hand. Bare parts that have to be touched or handled in the normal course of events should be at earth potential or properly insulated. 

Morningstar recommends a fuse between the solar panels and the controller (60 amp for my 45A controller).  The battery side should always be fused as close to the battery as practical.  I use ANL fuses by MaineSail's recommendation and they are an easy way to disconnect panels and battery.

 -- Spiff
Add Thank You Reply
The following 1 user says Thank You to Spaceman Spiff for this post:
This world isn't home (07-20-2017)
Spiff. What you posted reinforces my understanding that the problem is not equipment damage. What I found for my 12 volt system is it is necessary to fuse both ends of the cable from the controller to the positive battery. My panels are in parallel, and each requires a fuse to prevent the other panels feeding back into one panel if a failure/short in one panel. The internal panel circuit may not handle the 18+ amps from three remaining panels. I have a DPST switch to disconnect my controller from both the panels and batteries with one action. I do not have any accessories that would be fed from the solar if the battery is disconnected. My solar controller is connected to the battery. My accessories are only from the battery. Disconnect the battery from the solar, no accessories to be fried by the solar. The controller will not pass current above the set point charging voltage, 14.8. If it does it is not a good controller. I got a nasty shock from a 24 volt battery through an injury on my finger. Not life threatening, but I will not do it again.
Add Thank You Reply
Some parts of this are specific to a Zamp install, but I found the step-by-step instructions helpful from the Zamp website:
Add Thank You Reply
I am wondering what happened when they stuck the meter leads up the panels MC4's.
Sparky created, (Sparkles on some Saturday nights)  Max the Wonder puppy approved

2011 Ameri-lite 25 ft bunkhouse with 750w of solar and a 675 Ah bank
2003 Ford Expedition with 435w of tilting solar.
Add Thank You Reply

Forum Jump:

Users browsing this thread: 1 Guest(s)

Powered By MyBB, © 2002-2017 MyBB Group.