Tweet
How to Measure Array Power Ouput at the Charge Controller
We bought an off-grid cabin that came with a small 12V 4-panel solar system. The array is 2 mono and 2 poly. The panels are old and weathered, with no visible labels, so I can't tell the model or specs. I'd like to measure the power feeding into the charge controller from the array. How would I do that? (The charge controller is a cheap Chinese job and the controls are cryptic. Can't figure out how to get it to show me the input power from the array.) Utter NOOB here
-
Last edited by eric@psmnv; 05-08-2020, 04:38 PM. -
The best way would be a DC clamp on Ammeter. If you are trying to measure the output of the panels you will need to put a load on the system to make sure the charge controller is not limiting the panel output. If the batteries are fully charged then the charge controller will only pull enough Amps from the panels to trickle charge them.9 kW solar, 42kWh LFP storage. EV owner since 2012 -
Just place it over one of the wires. Checking a wire from the panels to the charge controller will give you the panel output in Amps. That times voltage will be Watts.9 kW solar, 42kWh LFP storage. EV owner since 2012Comment
-
Do you have any idea what the PV power is ? 400w, 600w ?
400W @ 14V (charging voltage) is about 22A. That's a bit high for a direct read meter, which is often limited to 10amps. So a clamp-on meter is the way to go.
In the meantime, using a VOLTmeter, measure the PV voltage at the panel side of the charge controller (at noon on a clear day) and compare it to the battery voltage
How to interpret the readings
For a small system, it's likely to be a PWM controller, and if the battery is charging heavily, the Panel voltage will be the same as the battery voltage. Once the battery has charged to 90% or so, you will measure a higher PV voltage than the battery voltage, which should be around 14V while charging.
If you have a MPPT controller, you will always read panel voltage (should be at least 35V for a MPPT to work) on the panel side of the controller, and battery voltage should rise to about 14V as the battery charges up.Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-ListerComment
-
Get a victron mppt controller. The app will show you everything. The only way i get max output is with drained battery (11.40 volts) and a decent load. My 75/15 Victon charge controller gets max charge current (15amps) in this condition only. Otherwise i never come close. Use my system for landscape lighting. Battery never falls below 12.20 volts. Stay away from cheap charge controllers. Victron is very good for the money. And the app works great for monitoring.Comment
-
Mike, I do have an MPPT controller, albeit a super cheap Chinese one. I have no idea what the PV power is because the panels are old and there are no discernible identifying markings on them. Whatever was there has long been washed away by wind and sun.Comment
-
Thanks for the suggestion, gasnet. Are you talking about something like this?
Comment
-
Super cheap Chinese MPPT charge controller often = PWM, not MPPT. Photo? Model #?2.2kw Suntech mono, Classic 200, NEW Trace SW4024Comment
Comment