You sure about all those statements? I thought grid tie meant feeding electricity back to the grid. If you are not grid tying, I’ve read from many that permits often are not required. At any rate, I strongly suggest OP should refer to his local municipal codes to determine what his options are and at the very least seek 2nd and 3rd opinions on this (and/or other) forums.If you want to add a lot of Solar PV Watts to assist in charging the Tesla, then you must either grid-tie (with expensive licensing and permits, possibly requiring PV installation from a relatively small number of licensed-and-approved PV contractors) -- OR you may build a totally separate system, with either a 120V or 240V Converter supplying "AC" Voltage into the Tesla charge cord. That would need the following components:
They do make some Inverters with built-in Transfer switches, but these are more for "grid backup" than "fully utilizing the Solar". You can program the Tesla to both a maximum Input Current value and a Maximum voltage shortfall value, and these can be separate values for 120v for 240v input. The Inverters also shut down the battery Voltage drops "too far", although this value is too low for most kinds of battery banks. (Some Inverters are programmable, and that's a very good feature).
- PV Array.
- MPPT Solar Controller(s), feeding a battery bank.
- Battery Bank (preferably "48V" rather than "12V" or "24V", because that allows for smaller wiring between the Battery Bank and the Inverter.)
- A big Inverter.
I feel that a battery bank is mandatory, for two reasons: First, many MPPT Solar Controllers can't even get started until a battery is connected; and second, the battery bank needs to hold up Voltage on the Inverter Input whenever clouds pass overhead for a short period. On the output side, I "feel" that pure Sine Wave Inverter output is pretty much mandatory - although I have no proof that Tesla's internal charger can't handle "Modified Sine Wave" from the 120/240V input, I'd hate to try it and then break it. Your Inverter output needs to look like the grid (pure Sine wave), with extremely low distortion and harmonics.
you can also connect your system such that grid feeds the inverter, then the inverter feeds the house main. This eliminates any chance of backfeed with no need for manual or automatic intervention.Thanks, Derpsy. I did fail to include the option of a using a Transfer Switch, preventing grid-tie but using the grid connection when input 120-VAC (or 240-VAC) is "unavailable" from the battery bank and Inverter.
Except for that case, however, if your PV panel is connected to the same Tesla outlet (120V or 240v) which is powered from the Grid, through a grid-connected home circuit breaker panel - than you ARE grid-tied, and there is no way for your home distribution panel to distinguish between "feeding into the shared outlet" versus "feeding into the Grid" when current is present.
In some cases, maybe, a particular Electric Utility provider and Municipality might allow you to provide power into them "for free", giving you no credit (by leaving a dumb meter and dumb billing in place). But Grid-tie is the mere attachment of a grid-compatible power generation device, and not necessarily feeding back power for credit.
Without a transfer switch to prevent connection, I can't imagine any electric utility which would let you connect an unqualified power-generating Inverter into "their" grid through "your" panel. A lower-quality Inverter (incapable of locking phase with the Grid, or with a bad waveform and too much THD) would be a disaster - for them. So the Tesla Solar outlet needs to be separate, or it needs to be connected through an automatic Transfer/Disconnect switch, or it needs to be officially grid-tied.
I hope this correction clears things up. With this offered as an addendum, I am quite sure about all of my statements so far. I have a pretty big grid-tie array on my own house, and I have wired another house (only from the Panel outwards), with special charging current, voltage-drop limits, and time-of day limits programmed into his model-S for connection for that particular outlet (which is recognized by its geographical location). It's been working great, and it was built right.
What are you using now and what size is the internal charger on your car? Depending on the model of Tesla you may be limited to 40 Amps. Tesla has changed that configuration over the years. I have used Clipper Creek, JuiceNet, the Tesla mobile connector and several others with success on both of my Teslas.Looking for suggestions on supplementing the charge on a Tesla
To clarify by, "outwards" I assume you mean behind or away from the meter in the direction of the loads. I have played around with turning my EVSEs on and off based on solar production but not had any luck modulating output. I would be interested in hearing more, but don't want to hijack this thread. However what you are doing may be relevant to what the OP means by using th word "supplement".I have wired another house (only from the Panel outwards), with special charging current, voltage-drop limits, and time-of day limits programmed into his model-S for connection for that particular outlet
I have two Teslas and I can only adjust the input current on the screen on the car. Where do you find the adjustment for "maximum voltage shortfall value"?You can program the Tesla to both a maximum Input Current value and a Maximum voltage shortfall value, and these can be separate values for 120v for 240v input.
You are correct, and I described three different things into a single sentence: The Tesla can specify a maximum charge current (not otherwise tunable) and a single spread of off/on operating hours for a given location. The "minimum Voltage" requirement was with regard to the Inverter on the DC input battery pack side, and it is also an off/on function. In going to a dedicated Outlet, power into the Tesla adapter will vanish when the Inverter shuts down.To clarify by, "outwards" I assume you mean behind or away from the meter in the direction of the loads. I have played around with turning my EVSEs on and off based on solar production but not had any luck modulating output. I would be interested in hearing more, but don't want to hijack this thread. However what you are doing may be relevant to what the OP means by using th word "supplement".
I am trying to picture how that would work assuming you are talking about a grid tie inverter. In the case where you describe the grid feeding the GT inverter there is no way that I know of to make that a oneway path. By the very nature of a grid tie inverter it is a bidirectional connection. A GT inverter needs to be able to export to the grid as a buffer since it is only designed to produce the maximum power from the solar.you can also connect your system such that grid feeds the inverter, then the inverter feeds the house main. This eliminates any chance of backfeed with no need for manual or automatic intervention.
have verified a test of charging at 1.5kW from a 3kWh goal zero pack for a short period of time. floating ground had to be addressed for error code to abate.I thought that even the "trickle charge" option (days to get a full charge) for a tesla was a couple killowatts!!
Normal charging was 10-20kw (240vac 40+amps).
those cars really suck the power; you will need a lot of panels to charge a tesla.
Have you considered just installing "Mr. Fusion"?
I just checked and the lowest i can set my internal charger is 5 Amps. That assumes 240 volts so that is 1200 Watts. Depending on the car I can get as much as 20 kWhrs overnight which can be 100 miles of range at that rate. I just checked and the max rate is 32 Amps which easily can put 200 miles of range into that car (Model 3) in less time than my TOU low rate window.I thought that even the "trickle charge" option (days to get a full charge) for a tesla was a couple killowatts!!
The simple workaround for that is to set the car to always ready and use a programmable switch to control a relay to turn on the power to the plug in which the Tesla is attached. I did that before I had a Tesla because my other EV had no programmable charging. I kept using that system because it was easier.So, if used for only one Tesla socket, through a Transfer switch, you are unable to set two different charging periods (off peak/night, and peak Solar). That's the main reason why I recommend that a Solar System which isn't inherently grid-connected should be done with separate outlets.
That rate is moot for a Tesla since the internal chargers are mostly limited to a lot less than that. On the other hand DC charging at a Supercharger can be as high as 250kW but briefly tapers down. Even then that is 37 minutes from 5% to 90%.70,000Wh/20,000W -> 3.5hr
Me too. If he is talking about DC fast charging that would not be optimal from solar. .I too am curious what "supplement" signifies.
My interest is finding a way of modulating charging based on solar production. I have no interest in charging my Tesla from my house bank of batteries. Even during a power outage I would rather do that from solar once my house batteries are full.Haven't seen many resources about modulating charging based on battery state.