A part with both a MODULE[ModuleDeployableSolarPanel] and RESOURCE[Electric Charge] will have little or no electric charge (current and max) at launch. The solar panels generate as normal

This is a minimal part for testing (just include a model and other needed stuff) `
PART
{
name = *
module = Part

RESOURCE
{
	name = ElectricCharge
	amount = 5
	maxAmount = 5
}

MODULE
{
	name = ModuleDeployableSolarPanel
	sunTracking = false
	raycastTransformName = suncatcher1
	pivotName = suncatcher1
	isBreakable = false
	resourceName = ElectricCharge
	chargeRate = 0.01
}

}
`

Minimal mods for this are MM, KSPI-Extended and a mod with parts like the one above.

Current release probably 1.18.5 fixes the issue.
Please check.
The problem was that the EC resource maxAmount was scaled depending on MAX output power = chargeRate, which is almost ZERO. This was fixed to give the same amount as the part originally have, and scale it with warp.

It does fix it. Just note it doesn't fix in flight vessels. I guess a manual edit to save files could fix it. But I just recovered and relaunched.
Closing the issue. Thank you for the fast support.

Sorry, I don't understand what the problem is

With only KSPIE as a meaningful mod, any part with both a ModuleDeployableSolarPanel and storage for EC will not store EC at all once launched.