Why Doesn’t My Charge Controller Work When I Connect It To My PV Array? – 5/3/2024



I happened upon this eloquent poem below about connecting a solar charge controller in an off-grid system.  I dare say it touched my soul and I thank you in advance for letting me share it with you:

In the dance of solar power, heed the order keen,
Connect the charge controller first, a vital scene.
For the battery craves its steady, gentle flow,
To nourish its soul and make its energy grow.

Next in line, the PV array, bright and bold,
Its radiant beams, like liquid gold, they hold.
But let not its power rush in haste and flurry,
For patience ensures a harmonious flurry.

Last in line, the loads, they wait with bated breath,
To receive the energy, avoiding any death.
Yet haste not, for the charge controller guards the gate,
In this orderly procession, it dictates fate.

So, in this solar symphony, let caution be your guide,
Connect with care, let wisdom be your pride.
For in the order of connection lies a secret art,
Preserving the charge controller, keeping it smart.

After giving these stanzas some thought and reflection, I offer my impression and interpretation–albeit biased by some of my engineering courses and years of experience in the solar industry.  In essence, these are the key points I believe the poem was trying to convey, if I can cut through its literary rhetoric and explain its message more matter-of-factly:

When installing an off-grid solar system, it is recommended that you connect components in the following order:  

  1. Battery to solar charge controller
  2. PV array to solar charge controller
  3. Electrical load to solar charge controller

And when disconnecting, you reverse that order. The Battery provides power to the controller to turn it on and allow it to function, so always make sure that solar and loads are disconnected before connecting or disconnecting the battery from the controller. This applies to all Morningstar controllers.  Additionally, connections from the battery, load, and array to the charge controller should have disconnect switches and over current protection such as a fuse or DC rated circuit breaker. 

Unfortunately, if an installer does not carefully read their operation manual, they might mistakenly connect the PV array first to the controller.  After making this connection they might be surprised to discover that their charge controller does not turn on.  Worse yet, they might damage the charge controller, even if using the right modules, since the charge controller is not first connected to the battery to power it on and allow its electronics to effectively regulate the power it receives from the array.  

Please remember and spread the word to others to first connect the battery to the solar charge controller when deploying an off-grid system.