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Words of wisdom: “If you want to see lots more amps coming out of the [charge controller], put on a 5-10A load and drop the battery to 50% depleted in the middle of a sunny day.” – John61CT1)
It is common for those with new solar configurations to worry about whether or not they are working. The worry is understandable because:
The last point may be counterintuitive. A fully charged system is observed to deliver very little power because the bank is already charged; the system is loafing, waiting for a load. It only cranks up power when you add a big load or start charging a depleted battery.
A poorly running system is observed to deliver very little power because it isn't set up right (or is shaded, etc) and can't do any better. Battery voltage is too low2) and doesn't meet needs.
This page is to help solar beginners tell what their system is doing without special equipment.
Icons and blinking lights are often misleading or oversimplied. They confuse and alarm more than they inform. Specifically, ignore the battery icon on Tracer/Renogy controllers.
Measurements, on the other hand, are useful when we learn how to read them.
To tell at a glance what your system is doing you need to find a couple pieces of info about your system. You will only have to look them up once; it might be worthwhile to write them down on a sticky note near your solar gear.
If you have an MPPT controller also look up these pieces of info:
These checks are admittedly crude but will help see if your system is getting it done. No expensive or specialized equipment is required. MPPT controllers in particular will reveal a great deal of information by how they interact with the panels.
For the examples below we will assume the system is set up this way:
Vabs 14.6v
Vfloat 13.8v
Vmp 17v
Voc 20v
In addition,
Vpanel - measured voltage of panel output
Vbatt - measured voltage of battery bank
During bulk charging with MPPT
During bulk charging with PWM
During Absorption charging with MPPT the battery will need less and less current.
During Absorption charging with PWM
During Float with MPPT
During Float with PWM
Adding a load can help reveal how much untapped power your system can access, and also prove that your system is working.
When adding loads to MPPT during absorption (or float)
When adding loads to PWM during absorption (or float)
These are general targets to ensure the system is working at the bare minimum to meet your needs. They give a big picture but no information about what is happening at a particular moment.
Are your batteries showing at least 12.1v (approx. 50% state of charge) in the morning? If so, continue to Afternoon.
If not, address this issue soon because discharging too deeply will damage the batteries. Consider these changes:
Are your batteries starting Absorption by noon-ish and completing Absorption by late afternoon? If so, continue to the next step.
Note: You can tell your batteries are in Absorption because the bank will be at Vabs, the controller's absorption setpoint.
Are you hitting sundown with at least 12.7v in your bank? If so, you can relax; your system is working well enough.