All electricity equal or not?

drscot

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I'm finally adding solar to my geothermal, energy efficient home with a 20 Kv (I think) Generac natural gas standby generator. The solar panels are calculated to replace 90% of my home's needs overall, although I am skeptical, they do guarantee production on an annual basis. We have frequent power outages here that sometimes last 36 hours, so the typical battery backups wouldn't come close to meeting my needs, hence the Generac. Sorry to all you purists. My question is, can a Tesla be plugged in at home and charge away regardless of whether the source of the power is the grid, solar, or my Generac? I love my Generac. Had it five years now, and it never misses a beat. Whole house (total electric) power no later than 30 seconds after grid failure. All appliances, HVAC, washer/dryer, lights, blast the music through open windows and doors and plant a sign that says "THE PARTY IS HERE, FOLKS!" It really is a magnificent unit for $8500 installed. A very good investment, but will it safely charge my Tesla or do I need to unplug during power outages at night when solar is dead? Just wondering!
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drscot

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Thank you for your reply. I vaguely remember somebody suggesting that the type of sine wave or something, I don't know from a generator wouldn't be compatible with the Tesla. I don't know. Yes, I can run EVERYTHING in my 2700 sq ft home simultaneously and have reserve capacity to boot. Side by side refrig/freezer, separate upright freezer, dishwasher, trash compactor, microwave, toaster oven, range and oven, maximum capacity washer and dryer, hair dryers,. I mean EVERYTHING. The Generac is FANTASTIC and I highly recommend them to anyone in a situation or location like mine where the infrastructure sucks. It is lights out for everybody else covering our several block development except for one other homeowner who put one in just like mine. Rain or shine, heat or cold, we are comfy and watching our favorite programs on TV (well, I don't know what they are doing) while the other neighbors are looking for cool or warm places to spend the nights after canceling orders for the Generac and building an inground swimming pool instead, so I don't feel too bad for them! But that was my question and why. Something about the type of electricity generated. Crissa, can you chime in on this please? I'd like to know your opinion. Thank you.
 

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Thank you for your reply. I vaguely remember somebody suggesting that the type of sine wave or something, I don't know from a generator wouldn't be compatible with the Tesla. I don't know. Yes, I can run EVERYTHING in my 2700 sq ft home simultaneously and have reserve capacity to boot. Side by side refrig/freezer, separate upright freezer, dishwasher, trash compactor, microwave, toaster oven, range and oven, maximum capacity washer and dryer, hair dryers,. I mean EVERYTHING. The Generac is FANTASTIC and I highly recommend them to anyone in a situation or location like mine where the infrastructure sucks. It is lights out for everybody else covering our several block development except for one other homeowner who put one in just like mine. Rain or shine, heat or cold, we are comfy and watching our favorite programs on TV (well, I don't know what they are doing) while the other neighbors are looking for cool or warm places to spend the nights after canceling orders for the Generac and building an inground swimming pool instead, so I don't feel too bad for them! But that was my question and why. Something about the type of electricity generated. Crissa, can you chime in on this please? I'd like to know your opinion. Thank you.
Would you be excited if CT could fulfill your requirements?
 

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Yes, you absolutely can charge your Tesla from your Generac but only if it is owned by the government. I say this because the Tesla manual says you should not charge from a privately owned generator. I'm not kidding about what the manual says but I am certainly being tongue in cheek about not being able to do it. There are some members here who have some interesting ideas about what can and cannot charge a Tesla and as to what's in or not in a generator. Don't know if they will emerge again this time round but there is only one reason you shouldn't charge from a generator and that's the cost. Given what you pay for propane and the efficiency of small machines a kwh from your generator is quite a bit more expensive than one bought from the utility. Most outages are a few hours so wait to dry clothes, turn off e-heat, don't run your kilns, don't use your electric ovens and don't charge during a power outage unless you have to. Less propane used means less $ AND that your tank will last longer in a prolonged outage too. But if you have to, you have to (hasn't happened to me - yet).
 

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Something about the type of electricity generated.
US mains power is transmitted as a 60 Hz near sine wave of amplitude 339.4 V. I say "near" because the waveform has some energy in it at frequencies other than 60 Hz i.e. at harmonics of 120 Hz, 180 Hz, 240 Hz etc, These distort the sin wave making it less smooth. The quality of power is often expressed in terms of Total Harmonic Distortion which is the ratio of the power at 120, 180, 240... Hz divided by the power in the fundamental (60 Hz). Utility power is quite clean - harmonic distortion of a percent or 2. Power from a good generator is perhaps a little higher (up to 3%) and power from cheapie generators can be higher than that. Harmonics can be a problem in machines that use steel such as a transformer or motor. The higher frequencies get converted to heat rather than work and gear gets hot. But your Tesla doesn't have any of this exposed to the line. The first thing it does is rectify the incoming waveform and it can do that to a square wave as well as a sine wave. Some people here think it can't and some people here think cheap generators have modified sine inverters in them. Neither true. If you want to be nervous about this get a THD meter (built into a clamp on Ammeter) and measure your generator's THD. I really don't know what to expect from Generac but Kohler and B&S ar in the couple percent department. Solar inverters are as good as the utility.
 
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The Cybertruck is going to have 60-80+ kWh stored up, if you have the tri motor, maybe 100 kWh.

Most likely you won’t need to charge it at all. Many of us will be powering the house off the truck when the power drops, not the reverse. I can go sip power from the Supercharger in town if I run low.
 

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Yes.

my 7.5kw solar panel system, usually makes a total of 30-50kwh a day (depending on winter or summer). Car /truck should only need about 30-50kwh kwh's for around town daily driving range.

So... with these numbers in mind:

-If you are tied to the grid, use max 220v 50+ amps charging. net balance should be even at the end of the day (although you are pulling from the grid for 0.5-3hrs).

-If you are not tied to grid and have a house battery , just set the Tesla to only draw low amps (>30 amps) so you can slow drain the home battery (8 hours maybe car charging time). The solar panels should just barrel keep up after 12 hrs of daylight and "refill the battery" in that 12 hrs.

-If you have no grid and no battery buffer... so all you produce must be used up right away, then set the tesla charging to draw very low amps (>15 amps?). This way as the energy is being produced at the peak times it will directly go into the car. you have to play it safe and go under what you think it will be making at that specific time of day . total charging time 12 hrs (maybe)
 

MEDICALJMP

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My question is this: Does anyone have experience where a large blackout occurred and this was in the area of the Super Charger station? Does the Super Charger have it's own supply off the standard lines?

I know some SCs run off of solar, but do they have their own battery back up? If so, how many charges can you get from them? If everybody and there sister now drives an EV will they be going to charge up after a storm and deplete the battery reserve and suck up all the available energy just as people storm the groceries before a big storm and stock up on bread, milk and fried chicken?

Inquiring minds want to know.
 

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My question is this: Does anyone have experience where a large blackout occurred and this was in the area of the Super Charger station? Does the Super Charger have it's own supply off the standard lines?
Right now, most/ all of them are grid tied. I'm not sure if they will still operate normally if there is a blackout and it is sunny. The three I've been to don't even have solar.

Musk has said he intends to isolate them from the grid. I'm not sure if that just means they will be able to separate from the grid or if he intends them to be their own little islands of power.
 

2000prerunner

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My question is this: Does anyone have experience where a large blackout occurred and this was in the area of the Super Charger station? Does the Super Charger have it's own supply off the standard lines?

I know some SCs run off of solar, but do they have their own battery back up? If so, how many charges can you get from them? If everybody and there sister now drives an EV will they be going to charge up after a storm and deplete the battery reserve and suck up all the available energy just as people storm the groceries before a big storm and stock up on bread, milk and fried chicken?

Inquiring minds want to know.

Sounds like you should build your own (or pay someone) solar setup with battery backup. This would grant you full energy independence from the grid if you added enough panels /battery capacity.

Even if the publicly available super chargers were "off grid" (which they are not), I would imagine that you would be fighting with others for access in the event of "no power". Much like like all the people who bum rush gas stations before shortages or natural disasters.
 

ajdelange

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my 7.5kw solar panel system, usually makes a total of 30-50kwh a day (depending on winter or summer).
4 to 6.7 hrs FSE (full sun equivalent) per day! I envy you. I am lucky if I get 5 in mid summer.

Car /truck should only need about 30-50kwh kwh's for around town daily driving range.
-If you are tied to the grid, use max 220v 50+ amps charging. net balance should be even at the end of the day (although you are pulling from the grid for 0.5-3hrs).
If your PV system produces 30 kWh on a particular (winter) day and you charge 50 kWh obviously the other 20 kWh must come from the utility. OTOH if your system produces 50 kWh on a particular day and you only charge 30 then you have 20 over to use for something else or lend to the utility (assuming net metering) to be repaid by them at night. Note that the CT will only charge at 11.5 kW (48 A @ 240)


If you are not tied to grid and have a house battery , just set the Tesla to only draw low amps (>30 amps) so you can slow drain the home battery (8 hours maybe car charging time). The solar panels should just barrel keep up after 12 hrs of daylight and "refill the battery" in that 12 hrs.
In this case you want to charge during the day at the rate the panels are producing i.e. if they are producing 6 kW at a particular moment you want to charge at 6 kW (25A). The reason for this is that the car is being charged using power produced by the array, not the battery and you have no "round trip loss" (energy lost in charging the battery plus energy lost in discharging the battery - 20% is a representative number). Sitting in the truck riding the charging rate to follow the sun is clearly not convenient so you would want to approximate this ideal by setting the charging level to something close to the panels' rating and charging during the peak production hours. Obviously you will need a bigger array as if you take all the production for the truck there will be none left for the house.

If you have no grid and no battery buffer... so all you produce must be used up right away, then set the tesla charging to draw very low amps (>15 amps?). This way as the energy is being produced at the peak times it will directly go into the car. you have to play it safe and go under what you think it will be making at that specific time of day . total charging time 12 hrs (maybe)
In So Cal you have lovely cloudless days. In Northern Virginia an August day looks like this:
Solar2Aug.png

You need a battery to buffer when the clouds roll by. That could be the car battery if the car were equipped with a controller designed to handle solar panel input (and I really hope the CT will be but if it is it won't be at the multi kW scale) but the current vehicles are not. They expect 240V and if the voltage drops below that by more than a certain amount the charger will shut down. It will start up again when voltage is restored but I can't believe all this starting and stopping is good for the system and you are clearly loosing sun while the charger is restarting.

Any way I don't see much point in a solar system without any buffering.
 

ajdelange

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My question is this: Does anyone have experience where a large blackout occurred and this was in the area of the Super Charger station? Does the Super Charger have it's own supply off the standard lines?
Mostly, no. I have never seen a backup generator at a SC station but I believe some do have them.

I know some SCs run off of solar, but do they have their own battery back up?
You have to have batteries in a solar system to "even" the load.

If so, how many charges can you get from them?
That depends on how big the batteries are and that depends on how many sunless days the system designers planned to cover and that in turn depends on the anticipated load at the station. If a stall services 12 cars per day and the average charge is 50 kWh then the batteries would have to be 600 kWh to cover a day and the solar 150 kW or so

In case of a prolonged power outage such as Puerto RIco a couple of years back I think BEV drivers are, in general, going to be SOL unless they have a PV system which, unlike most sold to homeowners, does not rely on the utility for its clock.
 

ajdelange

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Sounds like you should build your own (or pay someone) solar setup with battery backup. This would grant you full energy independence from the grid if you added enough panels /battery capacity.
Easier said than done.
 
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