Installing new caravan power system - advice welcome!

[matthewnz]

Hello all,

I am getting a new caravan and want to upgrade the power system in it as soon as it arrives. I have previously installed a DIY LIFEPO4 solar system in my existing caravan (link here, if you are interested) but this time I am going a little more "off the shelf".

I want to have enough power to go off grid for at least three days in cloudy weather. The load will be LED lighting and charging small devices, as well as a few fans. The fridge is 3-way so won't use any power when the caravan is not plugged into the mains.

Here is a diagram of my initial plan:


The current sensor connects to the EasySolar system and helps it to monitor incoming power.

The fridge is connected to the non-critical outlet on the EasySolar system, so that it is not supplied power when the caravan is not plugged into the mains. I will use a relay to switch it on and off, because the factory fuse and distribution box in the caravan is hard to change and I want to avoid having different fuses if I can avoid it.

I have decided to go with a 24V system to keep current more manageable between the battery and the EasySolar system when running on the inverter, this means I have to use a DC/DC converter to drop the voltage down to 12V for the lights etc.

I like the EasySolar system because it is an all-in-one system (nearly, anyway) and I can use the 240V outlets regardless of whether I am plugged into the mains or not, the system switches between it automatically.

I plan on wiring the panels in series, because in NZ it is more likely to get cloudy weather than partial shade on the panels.

This will cost me about NZ$5,000, not including the panels (they are already installed).

I welcome any advice or suggestions!

 

[time2roll]

3000 watt inverter seems large for a few fans and small items. Also seems large for the battery.

Smaller 500 to 1000 watt inverter would seem sufficient with a separate charge controller. I would probably stick with 12v on a reduced system.

Mains could power the non-critical loads direct and the smaller inverter can jump into the critical loads with a transfer switch.

 

[matthewnz]

3000 watt inverter seems large for a few fans and small items. Also seems large for the battery.

Smaller 500 to 1000 watt inverter would seem sufficient with a separate charge controller. I would probably stick with 12v on a reduced system.

Mains could power the non-critical loads direct and the smaller inverter can jump into the critical loads with a transfer switch.

Thanks for your points, you are right about the 3KW inverter being a lot.

I didn't mention (and I should have) that the one thing that we want to have working off grid is our coffee maker, this takes about 1.8KW.

The only options for the EasySolar are 1.6KW, 3KW, and 5KW. So, the 3KW is the only one that will power the coffee maker. It only needs to run for 5-10 minutes each day, so I am ok with the battery size.