What electrical panel work might we need?

[ajdelange]

I live in Northern Ontario and am wondering about the tesla wall as an option for charging the cybertruck.

The PW 2 has a capacity of 13.5 kWh (compare to 200 kWh and perhaps even more battery for the tri motor) and can only deliver 5 kW peak (implying 12.5 miles range added per hour of charging). But why take energy from the utility, store it in a battery and then dole it out at a slower rate to the car? If you can buy it at a cheaper rate during some hours which don't happen to be the ones during which you charge then of course that's the answer. I'm in Quebec and there is no such staggered rate structure so there is no such advantage. And even where there is the lowest rates tend to be offered at night when you are most likely to be charging your car.

Were also looking at redoing our roof. Should I be thinking about the solar roof in conjunction with the tesla wall?

Given that you are in northern Ontario you should be thinking about other reasons for wanting a solar roof as I don't believe that charging the car should be the main consideration. The two long poles in the tent are the latitude and snow. High latitude means reduced production from panels, summer and winter, because the sun never gets very high in the sky meaning that unless the roof is pretty steep (as it may be for snow shedding) you never get the sun's rays close to perpendicular to the panels. This can be made up for by adding extra panels and is somewhat also offset by longer summer days. Assuming that you size a system reasonably for summer it will be pretty useless in winter when the sun't elevation is very low and the days are very short. This is why I suggest that the car is probably not the main motivator. You probably drive as much in winter as in summer and you will use more energy per mile driven in winter. A solar system produces minimum energy when you need it most not only for the car but for heating (if you use electric heat as, of course we do in Quebec) and for lighting.

From the ROI perspective you need to thoroughly understand your supplier's position on solar. Hydro Quebec, for example, is most uninterested in supporting it and so does not purchase any excess generated (but will, I think, allow net metering thus not charging you for what you don't take from them).

As to the environmental aspect: Adding solar to a residence supplied by Quebec Hydro or a utility who buys heavily from them doesn't do much, if anything, to minimize CO2 production. The story is different if one is far enough north that the local plant trucks diesel in across the ice roads for a substantial part of the year.

Bottom line is that up north the question is not a simple one to answer. Powerwall for emergency power? Perhaps but we have already had a 3 - 1/2 day outage this season during which we used 169 kWh of electricity (heat pumps + baseboard electric). We'd have needed 13.5 powerwalls to carry us through that.

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[Jon Snow]

I was told that I have just short of the maximum allowed for a residence. I think it's 10 megawatts and I have something like 9.8 or something like that. I'll need to look at the documentation. I was also told that if I'm already connected to the grid that I can't disconnect from it; Is that true?

Correction:
9.88 kW Solar

Laws vary by region, so that will be a piece of homework for you

 

[Jon Snow]

I was told that I have just short of the maximum allowed for a residence. I think it's 10 megawatts and I have something like 9.8 or something like that. I'll need to look at the documentation. I was also told that if I'm already connected to the grid that I can't disconnect from it; Is that true?

Correction:
9.88 kW Solar

Not sure about Ontario to be honest. It doesn’t seem to be a problem here in AB.

 

[ajdelange]

The utility does not need your solar output. They do not want your solar output. They, therefore, put as much pressure as they can on the local regulatory agency to minimize the amount of solar that can be connected to their grid. It is the local rates board that determines how much you can install and connect and that is quite variable across jurisdictions. This is why it is important that one understands in detail the local regulations.

In some places what it permitted depends on your actual provable use of electric energy as evidenced by previous utility bills. In others there are prescribed limits. It is worth nothing that you can often install a bigger system than the utility allows provided that the system limits the power it passes to the grid to what the utility allows. It is, of course, questionable as to whether one wants to generate more than he uses plus what he can sell but sometimes the detailed calculus shows that it is the thing to do when load leveling is considered or when one wants more solar in the winter than he can get out of a maxed out summer system.

 

[Eye of Elon]

As a future Tesla newbie, i found this video informative, about charging and needing wi-fi to get software updates.

 

[Tinker71]

My business focuses on Return on Investment (ROI). My recommendation to people is to think like a utility company .. meaning long-term. Your array will generate for 30+ years and there is a good chance that you will be using more electricity in the future because of EVs and the electrification of pretty much everything. Right now, batteries are expensive .. they won’t always be. I am very curious about Tesla battery days in January as some of us think the 20 year battery will be announced due to Maxwell and Jeffry Dahn tech. This would effectively cut the cost of batteries in half from a ‘utility’ perspective. Message ... build with the option of adding batteries when the ROI is there. Your roof is an issue. I like metal roofing since racking is easier and the roof will outlast your array .. if you have asphalt there is a chance you will need to spend $3,000 or so 15 years down the road to remove and reinstall the array when your house needs to be reshingled. Powerwalls BTW are about 13.5 kWh storage ... Cybertruck is about 100 - 200 kWh .. so one PW wouldn’t do much really. For EV charging .. your best bet is to charge during the day with solar. Hope this helps.

Great info and analysis. I live in Utah. Power is stupid cheap. I am waiting for my existing 40 year comp roof to need replacement. I plan to go with a tile system for looks and not having to think about removal and replacement of panels. I have stupid large house and run the AC on max all summer. My worst power bill is $140 a month. The math is just not there yet. I am hoping for a big carbon tax down the line.

 

[Sgt. Glenn]

Great info and analysis. I live in Utah. Power is stupid cheap. I am waiting for my existing 40 year comp roof to need replacement. I plan to go with a tile system for looks and not having to think about removal and replacement of panels. I have stupid large house and run the AC on max all summer. My worst power bill is $140 a month. The math is just not there yet. I am hoping for a big carbon tax down the line.

I also live in Utah. My roof will need replacing in the next 18 months and I really want the Tesla Solar Glass roof. A Tesla rep told me that my area should be within the service area by then. My power bill today will not be the same after we add a CT and Model 2/3.

 

[CyberJagg]

Hello Jon,
I live in Northern Ontario and am wondering about the tesla wall as an option for charging the cybertruck. Were also looking at redoing our roof. Should I be thinking about the solar roof in conjunction with the tesla wall? Thoughts as your a solar installer?
Rich

Your Tesla power wall will not be able to charge your Cyber Truck as the Cyber Truck battery is roughly 7 times the capacity of the power wall. But the CT could charge you power wall a few times if necessary.

 

[CyberJagg]

For myself, I have a 200 amp service. But with 60 amps just for A/C I'm pretty well maxed out. I've only had level 2 at home before (max 32 amps, so it shared the 40 amp welder circuit).

I want to budget for upgrades to the electrical. What do current Tesla owners have for their service panels? Or better, what do any of you recommend?

Unlikely I will go solar (ROI isn't there for me) so no need to take that into consideration.

Thanks

You won’t need to get any upgrade on your service as 32 amp is still a great rate to charge at home. Also your 200 amp service is never maxed out at any given point because not all loads are being used at the same time. Even if you increase your charging amps to 60 amps, you’ll still be fine. The home chargers are mainly fused at 32 amps anyways. There are some higher amps charger on the market but it’s not necessary. I’m a certified electrician and electrical contractor in case you had any doubts in my answer.

 

[Cyber_Dav]

You won’t need to get any upgrade on your service as 32 amp is still a great rate to charge at home. Also your 200 amp service is never maxed out at any given point because not all loads are being used at the same time. Even if you increase your charging amps to 60 amps, you’ll still be fine. The home chargers are mainly fused at 32 amps anyways. There are some higher amps charger on the market but it’s not necessary. I’m a certified electrician and electrical contractor in case you had any doubts in my answer.

No doubt at all, Joel. Thanks for reply.

 

[ajdelange]

You won’t need to get any upgrade on your service as 32 amp is still a great rate to charge at home. Also your 200 amp service is never maxed out at any given point because not all loads are being used at the same time.

An inspector will look at the number of breakers installed in your panel. If you have up to 800 pole Amperes worth of breakers in a 200A panel (a single pole 20 A breaker counts as 20 pole amps and a dual pole 30 A breaker, for a heat pump for example, counts as 60; the main 200A breaker provides 400 pole amps) IOW if your installed breakers are around twice the main breaker (400 pole Amps) you will very probably be OK. If you get much over twice that then some questions may be asked. For example I had 1160 pole amps in a 200 A (400 pole Amp) panel which is 2.9 times the main breaker. When I had my electrician put in a 100 amp breaker for the EVSE that brought the total to 1360 which is 3.4 times the main breaker and the inspector balked. But when the electrician pointed out that the panel was laden with current transformers and that "This guy knows where every amp in the house goes." He was satisfied and passed it.

Even if you increase your charging amps to 60 amps, you’ll still be fine.

You can't. The most onboard chargers are accepting these days is 48 amps (some older Teslas will still accept 72 and some even older ones 80). But a 48 A charger requires a 60 amp breaker. The point of the previous paragraph is that it is ultimately up to a human being, the inspector, to decide whether to pass you or not. If you have a 200 amp panel with 680 pole amps of breakers installed and propose to add a 60 A breaker for charging (120 pole amps) that will bring you up to 800 and you will probably be OK. But if you have 850 installed and try to add a 60 A breaker then you might be questioned. You might argue that it will never draw more than 96 and that you only charge at night and that argument might be accepted but it might not. The most significant thing I have to say here is that having a good electrician is paramount. He will understand EVSE, the implications of NEC 625 and local codes, and will have worked with the inspector who has the final say so that there should be no surprises.

The home chargers are mainly fused at 32 amps anyways. There are some higher amps charger on the market but it’s not necessary.

There are dozens of chargers on the market. Perhaps the cheaper ones have fuses but the more sophisticated ones are programmed by the installing electrician to limit the amount of current they can draw to 80% of whatever size breaker has been installed. This programming is very important as not only does it open the EVSE's contactor if more current than the program limit is drawn but it tells the car how much it is allowed to request. Note that no one (AFAIK) except Tesla makes EVSE with the Tesla connector. Your truck will come with a J1772 to Tesla adapter so you can use other manufacturers' EVSE.

When it comes to EVSE size I'd say go to the largest you can install. There are lots of 32 A chargers on the market. They are designed to be wired to or plug into an outlet which is wired to a 40 amp breaker. If Tesla supplies the same UMC (Universal Mobile Connector) with the CT that it supplies with its other cars (and I suspect they will) you will have a 32 Amp charger which you can plug into several outlets up to 50A (though rather than the 40 you should be able to get from a 50A outlet you will be limited to 32). And you will be able to live with that. The CT is going to take about 400 Wh for each mile you drive it. 32 A at 240 V is 32*240 = 7680 watts so you will be able to replace 7680/400 = 19.2 miles of range for every hour of charging. If you install a 60 A breaker rather than a 40 you will be able to charge 50% faster i.e. you can get 9.6 more miles (for a total of 28.8) per hour. The incremental cost of a 60 A circuit vs as 40 A one should be modest and you ought to be able to argue for the extra 40 pole amps in the panel. But again I say that a qualified electrician is the one to consult on such a question.