Load setting through Controller

Welcome to the forum 116tv,

I guess this is the kit you have?

https://hqsolarpower.com/10-amp-12v-24v-pwm-common-postive-solar-charge-controller-with-lcd-display-and-5v-1a-usb-port/

When setting up your solar charge controller... Always connect the battery bank first, and the solar panels second (and disconnect first, then battery bank last). This is to ensure that the solar charge controller "boots" correctly. The charge controller boots from the battery bank and measures the bank voltage... More or less, less than 17 volts, the controller assumes you have a 12 volt battery bank. Over 17 volts, it assumes you have a 24 volt battery bank. If you connect the solar panels first, the controller can get confused during bootting--And in some cases can even be damaged by connecting solar panels first.

This controller has three sets of connections... Battery bank (which you connect first). Solar panel(s) connection (this would be your single 100 Watt @ 17.5 Volt Vmp @ 5.71 Amps Imp (guessing at your panel specifications).

And you have the "load" connections... Manual for your controller(?):

https://store-6ot2px3pbm.mybigcommerce.com/product_images/Big commerce/20A positive controller.pdf

The load connections... Probably have a maximum current of 8-10 amps... More load than that, the controller will turn off the loads (short circuit). I am a bit confused... The controller talks about 6 volt -- 6 volt output? And the Load seems to be mostly setup with outdoor landscape lighting in mind (turn on when sun sets, off when sun rises, say on for X hours after sunset, etc.).

And back to your questions... With the Load circuit disconnected--Does the solar+charge controller charge the battery (during the day)? If so, then the "charger section" is OK.

Next is what is your load? Is it an AC inverter? In general, AC inverters have their DC Input connected directly to the battery bank. The 8-10 Amp limit of most small "LOAD" terminals is just too small (too low of current) to operate an AC inverter... For example, if you have a 120 Watt inverter:

• 120 Watt inverter * 1/0.85 AC inverter eff *  1/10.5 battery cutoff = 13.4 Amp draw (worst case)

And most AC inverters can surge 2x rated output for a few seconds to a few minutes (>26 amps for above example).

So--I would hope that you solar+controller does charge the battery bank correctly.

The LOAD termimals are (most likely) not rated to power your AC inverter (too much current). Even if you have a very small inverter... The other issues may include (programmed LOAD for lighting--after sunset, or 6 volt output?), or simply the LOAD electronics have been "cooked" by the AC inverter load.

In any case, the typical answer is to ignore the LOAD terminals and connect the AC inverter though a fuse/circuit breaker and/or switch (protect wiring against short circuits, and turn off the AC inverter when not used--An AC inverter ON but not powering any loads will still draw something like 0.5 amps @ 12 volts (more or less, depends on your inverter brand & model).... And leaving the inverter ON without loads, on smaller solar power systems will usually take the battery dead (small solar+battery cannot keep up with inverter loads).

Also, many folks put "too big of AC inverter" on their smaller solar power systems... Your 12 volt @ 35 AH battery bank, I would suggest a maximum wattage inverter of:

• 12 volts * 35 AH * 0.85 inverter eff * 1/8 hour discharge = 45 Watt inverter nominal max inverter
• 12 volts * 35 AH * 0.85 inverter eff * 1/5 hour discharge = 71 Watt inverter suggested absolute max inverter

Your thoughts/questions?

-Bill