Options for my van solar system, potential problem with no load idle/parasitic loss

[antmanbee]

I have purchased most of what I need but have not set it up yet as I am still several weeks away form the solar setup. Still working on a bunch of other stuff in my van build.
I need some feedback and advice on what I have purchased already as well as for possible other components and how to possibly overcome the idle drain of the inverter.
So far I have purchased a Jakiper 48V 100Ah server rack
A Growatt 48V 3000W all in one 3000 TL LVM
3 Jinko 310W solar panels JKM310M-60L for a total of 930W
Spools of pure copper 12ga and 16ga wire for van lights, fans, usb outlets, water pump, 12V aux plug, etc.

The van will hopefully be all electric, no gas or propane.
I want to run a 4.3 cu ft fridge.
I would like to install a LG 9000BTU 120V mini split for occasional use. In other words, I would not stay in a hot or cold climate where constant use would be necessary.
I will have an 800W microwave and an induction hotplate for cooking.
Sometimes I may want to use an electric mattress pad during the night.
I have a Maxxair 14" fan that will be used quite a bit.

I will need to get a converter to go from 48V to 12V. I don't know which to get. I don't think I will need a lot of watts at 12V.
I will get a 6 circuit fuse panel for the 12V.

For the inverter no load drain I have considered a couple of things. The inverter would need to be on for the fridge 24/7.
One I could get a DC fridge. But I don't want that. I like a more regular type fridge.
I could get an additional inverter for lower loads that has much lower no load waste.
But I don't know of such an inverter for a 48V system. Maybe I should have gone with a 24V system. More options are available for 24V.
Does anyone know of a 48V, low loss from idle/no load inverter that would work for this? Really it just needs to run the fridge. But it also needs to be able to handle the start up surge of the compressor of the fridge.
I also thought that maybe a timer that cycles the inverter on for 15-20 minutes each hour and then off for the remainder would cut down on the wasted watts considerably.
Also maybe I have enough solar that it will not even be an issue. 930W is quite a bit for a van. There is no more available roof space for more solar.

I would appreciate any feedback or suggestions or criticisms.
Any other suggestion as to what to incorporate into the electrical system design or solar design are welcome.

 

[rmaddy]

Regarding your solar - I have 990W flat mounted on the roof of my trailer. This time of year I get a max of about 460W midday and that's at near freezing temperatures on a clear day. So don't expect to get your full 930W unless your panels can be tilted at the perfect angle.

Have you done a proper energy audit so you know how much battery you really need on most days? Going all electric is a challenge. Use a Killawatt meter and figure out how much energy the fridge really uses each day. Test it in realistic use - load it with groceries and in summer heat.

Given that this is for a van you really should also setup a DC-DC charger so you can recharge your battery while driving to make up for cloudy days or days where you camp in shady areas.

 

[antmanbee]

My panels will be flat mounted, no tilt. I was not expecting to get the full amount. I do hopefully expect to be farther south and not have near freezing temps at noon. I have not found a lot of published data for a similar setup as I will have, to know what to expect for real world energy generation. I know I will find out eventually when I am out in the van in the real world.

I am unable to do an actual test but I have spent time researching and calculating my approximate energy usage. All in for the daily usage including the microwave, induction hot plate, lights, laptop, maxxfan on low speed, and fridge should be in the neighborhood of 1400Wh. This would not include heatpump usage or electric mattress pad. Using gas would not save me a lot because I probably only have about 3-400W of cooking usage per day which is a total of 15 minutes on the microwave.

My idle usage of my Growatt could be almost as much as my actual usage. This is what I am most concerned about and trying to figure out a solution.
Also on an unrelated question, Is it ok to mount the Growatt to plywood or do I need a fire rated material? What is recommended? I don't want anything heavy like cement board.

I have also thought about a DC to DC charger. My van has a 135A alternator which may be suitable for a 20A DC charge.
What suitable 12V to 48V chargers are available?

 

[eXodus]

My idle usage of my Growatt could be almost as much as my actual usage. This is what I am most concerned about and trying to figure out a solution.
Also on an unrelated question, Is it ok to mount the Growatt to plywood or do I need a fire rated material? What is recommended? I don't want anything heavy like cement board.

you can set the Growatt to power save mode. Works good on old mechanic thermostat fridges and A/C units. The Inverter only turns on when the fridge turns on. So the inverter basically measures in a sleep mode - if a load connects- and then ramps up the power (and idle use)

Don't get a fancy fridge with electronic controls, that will keep the inverter awake and drawing power.

The Growatt is in a Metal enclosure, which is fire rated by itself. In a Van i don't think it really makes a difference depending where you got it mounted. In case you ever got a fire, the whole thing will burn down anyhow.

In a house it makes difference, since the hardiboard allows the inverter to burn out without igniting the structure.

 

[antmanbee]

The fridge will be a basic manual defrost unit.
I had read that the power save mode did not work that well especially if it was a lower load. A small fridge draws 60-80W.
Maybe the startup surge is enough to make it work.

Regarding the fire rated back board, that is pretty much what I figured that the whole van is flammable and I will have an extinguisher and a smoke detector as my prevention.
I also thought I could mount it with an air gap of 3/4 of an inch to the back board so that if the unit burned out it would not transfer the heat to the back board. At least I wont be sleeping on top of it.

 

[eXodus]

The Inverter will not wake up when you plugin a charger for a phone or Laptop. Switching power supplies it completely ignores.

The way I understood the power save mode works is:
The Inverter is measuring the resistance in the circuit every few seconds. When the resistance is very high to indefinite (nothing connected) it stays sleeping. As soon it detects some resistance (a motor is perfect - resistance goes to almost zero through the coil) it turns on the power and checks if amps are flowing.