Distances Within Installation?

[RHinCT]

I just purchased a house and am contemplating a Tesla solar installation with Powerwalls. So of course I have some questions.

The house faces south, less than ten degrees off from true south. The main roof on the south side is 58 feet long, plenty of room for panels. Power comes into the house at the north-west corner, with the panel in that corner of the basement. The garage, where I hope the Powerwalls would be, is at the opposite end of the house, 74 feet from the power entrance. Where would the inverter be located in such an installation?

Does it pose any challenges if the Powerwalls are in the garage, 74 feet and more from the panel and meter? I guess I also should ask... Do Powerwalls ever get installed in a basement? (I hate that idea, but there is room there, and and a bilco door for direct access.)

(For the curious, the location is Connecticut, and the power company is Eversource.)

Thanks!

RH in CT

 

[miimura]

Nothing you stated above presents any particular difficulty. Some locations more be more expensive than others. If the basement is a shorter wire run than the garage, it probably makes more sense to put Powerwalls there unless you specifically want the eye candy.

 

[BrettS]

Frankly the basement is probably a better location for the powerwalls than the garage anyway because of the temperatures. Powerwalls can be installed in a wide variety of temperatures, but they prefer to be installed in more mild temperatures. In particular, in freezing temperatures they can be a bit inefficient as they try to warm up and start charging in the mornings. I suspect that in the basement they would be kept warmer in the winters and cooler in the summers.

They will work in the garage if you really really want them there, but personally I’d go for basement if I had a choice.

 

[RHinCT]

Well I sure am glad I asked. I simply assumed that the garage was the preferable location. The basement is huge, and mostly empty. The garage is large, but I was a bit concerned about wall space.

Thank you both for diminishing my ignorance!

 

[marklin]

I am planning to move to Norwalk or Danbury, CT. Which electric company has the best rate for charge electric vehicle at home? Or there is only Eversource that service the area? Thanks.

 

[Vines]

Powerwalls absolute limit is around 150' wire length for communication from Powerwall to the Gateway.

Other parts of the system can be further apart.

 

[Doom Man]

Related question: how long is "too long" for the wires from the panels to the Gateway? My Gateway, panels, and PW's are within a few feet of each other, but a foul-up on the installation made the panel-to-Gateway wiring run about 100 feet when it could have been less than half that. I wasn't sure how much power you use from resistance by doubling the length of the run. FWIW, the panels have microinverters, so it's AC power the whole way.

 

[BGbreeder]

It depends on the gauge (resistance) of the wire used. Power loss is current squared times resistance. In general, wiring is sized to have
3% loss or less over the expected run, so your installers should have corrected for the longer run with a lower resistance wire (smaller gauge/larger area). Some people even use 2% to promote energy efficiency.

calculator to calculate losses

I wouldn't lose sleep over it. Unless you had a shade tree electrician do it, it was done to NEC code.

All the best,

BG

 

[jrweiss98020]

I guess I also should ask... Do Powerwalls ever get installed in a basement? (I hate that idea, but there is room there, and and a bilco door for direct access.)

Mine are in the basement, in an old utility room now used only for storage. Why do you hate the idea?

 

[Vines]

It depends on the gauge (resistance) of the wire used. Power loss is current squared times resistance. In general, wiring is sized to have
3% loss or less over the expected run, so your installers should have corrected for the longer run with a lower resistance wire (smaller gauge/larger area). Some people even use 2% to promote energy efficiency.

calculator to calculate losses

I wouldn't lose sleep over it. Unless you had a shade tree electrician do it, it was done to NEC code.

All the best,

BG

The company I work for is one of those shops that oversize wire for 2% power loss or less, and it certainly costs more. Hopefully in most cases this is value added, but most customers probably don't notice. All of our rooftop conductors from the rooftop strings to the 20A breakers in subpanels is #10 or #8 AWG Cu.

In general, power loss for typical residential sized 240V inverters (about 50A continuous) wont get too crazy until you exceed 100' when looking at #6 Cu Wire.

 

[Uncle Paul]

Tesla does an initial engineering plan when order is places. Prior to installation they usually send out a knowlegeble prep inspector that will do a physical inspection and come up with a plan of action for the installers. They will take into considerations local building codes, efficiencies and ease of installation. You will be able to add input and suggestions, but Tesla will have final say in installation.

 

[JPP]

Better be sure that your local building codes approve of your choice of location of the Powerwalls (like a basement), and if they are easily accessible to your Fire Department to reach a hose to extinguish a fire. Also need to know if they will require additional disconnects if the Powerwalls are 'remotely' located.