Installation manual

Some MPPT controllers contain

programmable "auxiliary" relays that

can be used to control larger DC/DC

solid state relays (SSRs) to send

surplus DC generation to hot water

elements.

A new MPPT controller made by Midnite Classic and called the "KID" can divert directly to a

resistive element and no external SSR is needed. This is the only product we are aware of

that can do this. The "KID" can also divert on the input or output sides of the regulator as

shown.

Often it will be a better idea (as standard 120V water element can be used) to divert the

incoming power to a heater as in the "PV trigger" configuration shown in section 5.11. This

will operate the heater at a higher voltage, and prevent nuisance tripping of the Klampit

crowbar (if fitted).

If your MPPT controller is not fitted with an internal programmable relay (not needed if you

use a KID) and you wish to divert surplus power to a heater then you have several options:

 Use an auxiliary relay in your inverter if it has one

 Change the MPPT controller to one that has one

 Fit a Morningstar relay driver or similar standalone device for controlling relays,

based on battery voltage levels (as shown in picture below).