Hi all. Can anyone advise on my issue.
Have fitted a 200 mono crystalline solar panel. Connection to controller is by proprietary solar cables, via double pole switch. Controller is Victron MPPT 20/100. Power is fed into lead acid 120Ah sealed proprietary leisure battery. Also connected to the battery is a 10amp mains charger, and a B2B charger which delivers charge from alternator when driving. When stationary, with engine off, and without access to shore mains supply, the battery is being charged by the solar panel. I’ve noticed that the wattage reading on the controller sometimes jumps around like crazy - rapidly changing from 1-2watts, to 50watts or even 120watts, and many different readings in between. This happens in bright sunshine conditions, with zero cloud or shade.
I’m wondering if anyone might have an explanation?………
Start at the panel and measure the volts, & amps or watts. Are they steady?
Do the same at the controller input, then the controller output, basically anywhere there is a connection.
This should narrow it down to where the actual problem is.
If the battery is full, there may not even be a problem.
Thanks. Yes, that makes sense. Anyone recommend a tester?
I was extremely careful about wiring all the components, and I’ll be very surprised if there is a fault within the circuit. My thought was that maybe the permanent connection of the mains charger (even while not operating), and the B2B charger (also even when not operating) might be causing the panel wattage to jump up & down when solar charging is operating.
Most multi meters should work.
B2B or shore chargers should have no effect if not in operation, but a full battery could cause erratic readings. The controller coming on, then determining the battery is already full, or nearly full, thus reducing the charge.
Different controllers are different, some will report input & output, some won’t. You might have to change your settings between input & output readings. A digital volt meter can give you a decent idea of your batteries current charge status. (or multi meter with dc voltage function)
Thanks for that info. It does seem to happen on float charge. Having said that, the battery does not seem to charge above 90% - even with solar connected for days, with no load being placed on the battery.
Some controllers can be adjusted for that. Consult the manual for that…
Cheers all. Ta for your input.
In different environments, the temperature of the solar panel is different, and its output power will change with the temperature, which may also be the reason for unstable readings.
If dust and dirt accumulate on the surface of the solar panel, it will hinder light absorption and affect the output power.
If the controller parameter settings do not match the solar panel and battery, such as the maximum power point tracking (MPPT) parameter settings are improper, the controller will not be able to accurately track the maximum power output point of the solar panel, and the power reading will be abnormal.
I am definitely not an expert, but
makes it sound like some chargers deliberately only charge to 80% or 90%, to avoid doing harm to the battery. Only the most sophisticated chargers are designed to safely go higher long term without much risk of battery damage. But I don’t know how that relates to your hardware. Also, it says some chargers include pulsing on fully charged batteries, which would result in voltage fluctuations. Again, not sure how much that would affect you.