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Charging off grid ( solar only)

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Aloha, We have a M3 on order. We're off grid ( 6.1kw, 48v capable of 24amps, installing 240 circuit)) we know we cant charge at night. our batteries are full at 10 am and have 10-4 pm of solar charging available. My question is, will the model 3 adjust the charge rate as voltage fluctuates ( cloud passing over, fridge kicking on etc). We're hoping to get 12-16 miles per hour charge. Mahalo Nui
 
Aloha, We have a M3 on order. We're off grid ( 6.1kw, 48v capable of 24amps, installing 240 circuit)) we know we cant charge at night. our batteries are full at 10 am and have 10-4 pm of solar charging available. My question is, will the model 3 adjust the charge rate as voltage fluctuates ( cloud passing over, fridge kicking on etc). We're hoping to get 12-16 miles per hour charge. Mahalo Nui
Hopefully your inverter will keep a reasonable voltage coming to your loads. That's sort of its job, no?

The 3 is tolerant of voltage decreases, and will even decrease amperage draw if it sees the voltage drop somewhat. That said, I believe it will also terminate charging completely if it sees too much of a decrease, interpreting it as a failing circuit rather than just mild overloading. It will 'happily' connect and start charging even at 185 volts(seen this myself, on a 208V commercial circuit with stupidly long wires(!)), but I'd bet dropping from 240 to 185 during a charging session would be considered a fault.

Adding to this the amount of delivered charge, even if the car maintains the amperage, would decrease as voltage decreased.
 
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Hopefully your inverter will keep a reasonable voltage coming to your loads. That's sort of its job, no?

The 3 is tolerant of voltage decreases, and will even decrease amperage draw if it sees the voltage drop somewhat. That said, I believe it will also terminate charging completely if it sees too much of a decrease, interpreting it as a failing circuit rather than just mild overloading. It will 'happily' connect and start charging even at 185 volts(seen this myself, on a 208V commercial circuit with stupidly long wires(!)), but I'd bet dropping from 240 to 185 during a charging session would be considered a fault.

Adding to this the amount of delivered charge, even if the car maintains the amperage, would decrease as voltage decreased.
Mahalo! would the M3 automatically start charging again once the voltage/amps return? ( It will be a pain to have to manually restart the process every time a cloud passes over)
 
Aloha, We have a M3 on order. We're off grid ( 6.1kw, 48v capable of 24amps, installing 240 circuit)) we know we cant charge at night. our batteries are full at 10 am and have 10-4 pm of solar charging available. My question is, will the model 3 adjust the charge rate as voltage fluctuates ( cloud passing over, fridge kicking on etc). We're hoping to get 12-16 miles per hour charge. Mahalo Nui
In this situation, you really want to get an EVSE that can modulate the pilot signal to the car according to the solar power available. I don't know of an off the shelf solution for this. In order to hack something together you would have to have access to the solar system's parameters like battery SOC, battery charge/discharge power, and solar power. Then you could send a "available charging power" to an EVSE like an OpenEVSE that can adjust the pilot signal so that the car will observe that charging power level.

If you give more details about the off-grid inverter and battery system you're using, someone may be able to point you to useful information on how to implement it.
 
Mahalo! yes I need to find a software based "smart charger" that adjusts based on what's available. The system is 6.1kw 48v ( 4xsimpliphi LFP batteries) 2 outback inverters ( master and slave that kicks in for higher loads) 2 flex80 charge controllers.
 
Your battery storage will act as a buffer for any drops in solar output. But the car will not adjust charging rate on its own. So you will want to set it to a fairly low rate to have minimal conflict with your home loads and battery storage.
fantastic, I think the 4 LFP batteries are capable of being that buffer if solar production dips. I'm getting great input on this thread ! The idea is to charge as much as possible here, then the wife can charge it on L2 charger at work ( no Tesla chargers on the big island :(
 
In this situation, you really want to get an EVSE that can modulate the pilot signal to the car according to the solar power available. I don't know of an off the shelf solution for this.
There is for the European Type 2 (mennekes) AC connector: The myenergi zappi. That, along with a Type 2 to TPC adapter, might work.

For North America, with the J1772 connector, an Elmec EVduty Smart-Home EVSE with an EVduty Smart Current Sensor might work with the Tesla J1772 adapter. It's designed for "Dynamic Power Management" but not specifically for solar, so research would be required to determine suitability.
 
Mahalo! yes I need to find a software based "smart charger" that adjusts based on what's available. The system is 6.1kw 48v ( 4xsimpliphi LFP batteries) 2 outback inverters ( master and slave that kicks in for higher loads) 2 flex80 charge controllers.
Do you have the Outback OpticsRE system set up for your system? Do you have a MATE3? Can you see the SOC of the SimpliPhi battery bank?
 
Mahalo! would the M3 automatically start charging again once the voltage/amps return? ( It will be a pain to have to manually restart the process every time a cloud passes over)
Sadly, if the car stops charging because it sees the voltage drop too much(but not to zero), it is unlikely to restart charging on its own.

The good news is like others have said, your batteries should cover you if clouds block your panels.

Do you really need 14-16 miles per hour charged? Even the big island doesn't seem all that big!
 
AFAIK, there is no off the shelf solution for off-grid systems. MyEnergi Zappi is only for on-grid systems. However, OpenEVSE and EmonPi should work with some customization. The charging limit control updates need to be fast enough to avoid the M3 charging shutoff due to instability because once that happens you will likely need to manually disconnect/reconnect the charging adapter to reset it. You will need to setup battery voltage/SOC monitoring (instead grid power), load monitoring and customize (i.e. programming) the control update logic for off-grid setup.
 
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MyEnergi Zappi is only for on-grid systems.
The Zappi has "eco+" mode, which they claim pauses charging when surplus local, off-grid power isn't available. In this mode, it shouldn't matter whether or not you're connected to the grid.

If it were me, I'd consider contacting Elmec to see if their system would work, and/or whether they'd be willing to make any necessary software changes for their Smart Current Sensor to work with off-grid variable power. It might give them a new marketing opportunity.
 
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I have a Generac PWRCell system and charge our M3's from solar. I just adjust how many amps I'm charging the M3. Now that the Tesla App allows you to make the adjustment, it's much easier than when I had to set it in the car. We both work from home so we don't put many miles on the cars. I keep them between 40 - 80% SoC depending what our upcoming driving plans are. Maybe every 2-3 months I'll change them to 95% to help with battery management, but I really don't care about the car's range reading anymore. On a sunny day I have enough excess that I can charge at 20 - 24A for about 2 hours depending on our house usage. The rest of the time I adjust the M3 between 8A - 17A. I charge our PWRCell to 80% before I charge the car. I just balance the car charging so I have enough excess to run the house and put 1.5-2Kw into the PWRCell until it is 100% SoC. Partly cloudy day I'll adjust the M3 between 5A - 13A and let the PWRCell assist when the sun is behind clouds. Full cloudy day I can typically get several hours at 5A - 10A but most times I just wait for a better solar production day. We are grid connected and can charge at 40A if needed. Our electric co-op doesn't have Net Metering and I get a flat .0355/Kwh. With the M3's and Solar we qualify for their Solar+EV Time-Of-Use. I'm waiting for Generac to provide API's to see what I can automate, but it really isn't much work manually changing the M3's charge rate.
 
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Sadly, if the car stops charging because it sees the voltage drop too much(but not to zero), it is unlikely to restart charging on its own.

The good news is like others have said, your batteries should cover you if clouds block your panels.

Do you really need 14-16 miles per hour charged? Even the big island doesn't seem all that big!
Wife's commute is 80 mi round trip ( Big Island is larger than Connecticut 2400+ square miles!)
 
I don’t see how any third party charger would help - isn't charging start/stop controlled on the car side?
An EVSE can dynamically vary the current it reports it can provide, to match the amount of current available from solar (or whatever) at any instance in time. The car will only draw up to the amount of current the EVSE says is available. Of course, the car can decide to draw less than the maximum reported available or even stop charging altogether.
 
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Zappi doesn't know how to treat an off-grid battery inverter which needs to be charged
True, that would be an issue with any system with local battery storage, whether on or off grid. It would have to be decided (likely by the owner) how excess solar power is distributed; between local battery storage, the car, and possibly to the grid, with what priority and/or percentage, and possibly even based on time of day. If connected to the grid, you may also have to decide whether you ever want use grid power to charge your car and/or local battery storage.

An EV with vehicle-to-grid capability would further complicate the equation.