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diy solar

Off GRID tiny home with EV

Joined
Jul 6, 2020
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Hey Legends,
Life long dream of taking my tiny home off the grid. Finally got enough money together and have gathered panels for free.

Chasing recommendations for:
-Hybrid Inverter
-EV charger

Bonus recommendation:
Some sort of simple to setup in-home display that I can throw some CTs on + shunt and show solar production, usage and battery SOC in real time.

I use 5kw per day.
My EV (arriving soon). Will have 60kw. V2L (not v2g).


I would like to use the EV as a backup backup when I'm short on power or feel like using extra power.

So I was thinking about AC coupling with a hybrid (limiting export to zero as V2L is one way).
So if I'm low on power in the house batteries I want to charge from EV (pseudo grid) through the inverter. Rather than have a separate house battery charger.

Also, I would like a recommendation for a smart charger that will send excess power to the car when the house batteries are full. I'm not sure if any chargers have the ability to sense when batteries are full. But I could probably make some sort of current sensing relay that detects when current is going IN through the panels and NOT flowing to batteries. Then use a standard charger.

The EV charging isn't critical, hence the lowish solar array size. But it should be big enough to do some significant charging as a load dump and would be extra convenient to get top ups at home and on my days off. As I have the ability to charge my EV for free at work as an extra extra backup.



Attached is the photo of the layout.


Thanks heaps
 

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EV charging is easy. I recommend something small around 16 amps but even that is 4kW and maybe a bit much. Consider something adjustable to what is available.

My vision of V2L would be a simple battery charger to top up the home battery during an extended need. Again I would not max out the source but maybe closer to 50% max.

Often the charging is controlled with a phone app. So maybe something could send a text when there is available power. For the most part I think this could be managed manually.
 
You mentioned gathering panels for free? Are they all the same, how many and what are the specs. What is the voltage of your battery bank?
 
Yeah I have collected just over 6kw. Strings of 10-12 250w. All pretty similar voltages and current ratings.

I'm going for a 48v battery.

Am I missing something?
 
Check the charge current of the inverter compared to the V2L. Some V2L have limits in terms of power they can provide. Also, I'm not sure if V2L works all the time, or only when the car is actief ('key in ignition')

Especially in the last case you want to charge as fast as possible, fully using the V2L the car can provide. It doesn't make sense to have a hybrid inverter which does only 10A AC charging....

Another option might be using a separate inverter and MPPT, and use a charger for V2L charging using the full power.
 
Good point,

The V2l is 15a 240v.


I'm now thinking the hybrid is a waste of extra money. When I can use the OFF grid ones with grid as backup if need be. I don't need to export to the grid.


The inverter I like the look of is
https://m.alibaba.com/product/17000...800000","type":"appDetailShare"}&from=Android

It has 120A AC charger.
So for the V2L I would have to limit the charge current, as the EV would be the utility/grid so I don't trip the car.

Any better ideas for inverter?
 
120A @ 48V is approx 5700 W from the grid, excluding losses.

With 'only' 15A you need to reduce it till approx 3500W.

Fine if you don't have a grid, don't need the 120A charging (have sufficient time to charge using 'only' 3500W) or have an adjustable input like eg a Victron Multiplus.

Otherwise you might consider a dedicated smaller charger for the V2L charging. Might be needed anyway if your grid is not 240V
 
Thanks for that ?

I'm happy with a slow charge of 3500w from the V2l.
That will charge the batteries in 4-5 hours while I sleep at night.

I'm hoping that I will predominantly use my battery bank and solar in the day, plus the leftover solar (which should be heaps) for charging the battery. Also, my in-house battery bank is just 48vx280ah.

I currently live with a 15a 240v feed into this house and have lived with that for 10 years so it will more more than adequate.

Any more power will be luxurious.

I'm pretty close to pulling the trigger on the inverter now. The final big spend in the project ?
 
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