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Newbie capacity question - ordered 4kw system

Hay2000

Member
Sep 1, 2020
33
11
ca
Hi All,
First of all, thank you all. I've learned a lot from this forum.
I recently order 4kw system and was scheduled for site inspection, but with few more photos, they said it's not required as house is less than 15 years old. So I hope it's okay... waiting for next step.
I've a question about capacity.
We moved into this house less that a year ago ( 10 PGE bills ), which avearages about $90 Electricity bill and 360kwh per month. As per Tesla contract, 4kw system ( 12 panels, 330-345 ), generates 6482kwh annually. I do not have EV/Hybrid at this point . But planning to buy one soon. Also the inverter is 3800 with optimizers, which has max input of I think 5600.

I understand that lots of factors come into play when we talk about annual generation.
I know, this is more than enough for me as of now. My question is, will it be enough with one addition of Hybrid/EV vehicle ?
My guess is not, but want to check ....
I know it depend upon which car I buy later.... but mostly hybrid ( not EV )
what do u guys think ?
Thanks.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,871
9,879
Riverside Co. CA
Hi All,
First of all, thank you all. I've learned a lot from this forum.
I recently order 4kw system and was scheduled for site inspection, but with few more photos, they said it's not required as house is less than 15 years old. So I hope it's okay... waiting for next step.
I've a question about capacity.
We moved into this house less that a year ago ( 10 PGE bills ), which avearages about $90 Electricity bill and 360kwh per month. As per Tesla contract, 4kw system ( 12 panels, 330-345 ), generates 6482kwh annually. I do not have EV/Hybrid at this point . But planning to buy one soon. Also the inverter is 3800 with optimizers, which has max input of I think 5600.

I understand that lots of factors come into play when we talk about annual generation.
I know, this is more than enough for me as of now. My question is, will it be enough with one addition of Hybrid/EV vehicle ?
My guess is not, but want to check ....
I know it depend upon which car I buy later.... but mostly hybrid ( not EV )
what do u guys think ?
Thanks.

wow... 360 kWh a month. Thats phenomenally low usage. What is your driver for wanting to get solar, I am curious of? As for "is this enough if I buy X plugin car" that would depend on battery size, miles driven, etc... efficiency of car, etc, so there is no way to really guess at that other than to say its "likely" with your usage being that low currently, any plug in car you buy would add at least 50% more electricity usage to your home per month, and a BEV would likely at least double your daily usage.
 

getakey

Active Member
Jan 28, 2020
1,247
415
95762
unless it is a pluggable hybrid, it does not matter. If pluggable, most hybrids have small battery capacity. Not sure if you can go on EV Rate plan with pluggable hybrid. If you can (and are PG&E), better to charge during off peak than charge from solar
 

wjgjr

Active Member
May 11, 2020
1,218
952
Silver Spring, MD
Strictly in terms of usage, if you assume 360 kWh/month, this is 4320 kWh/year, which leaves you with 2162 kWh extra annually. You mention about equipment and other items, but the assumption is Tesla has taken all of that into account when estimating annual production. It seems like 30 kWh/100 miles is a fairly average number for electric/hybrid vehicles, which would suggest you could get about 7,200 miles of electric driving from that excess, depending on the vehicle.

Of course, this just addresses energy balance over the course of the year. It does not address cost balance nor seasonal fluctuations. From what I've seen of CA and TOU rate plans, so much of this depends on when you generate and use energy (and powerwalls come into play as well.) So there is more work to do, depending on your goals/priorities for getting solar, to estimate break even on pricing.
 
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Hay2000

Member
Sep 1, 2020
33
11
ca
wow... 360 kWh a month. Thats phenomenally low usage. What is your driver for wanting to get solar, I am curious of? As for "is this enough if I buy X plugin car" that would depend on battery size, miles driven, etc... efficiency of car, etc, so there is no way to really guess at that other than to say its "likely" with your usage being that low currently, any plug in car you buy would add at least 50% more electricity usage to your home per month, and a BEV would likely at least double your daily usage.

Yes... From all 10 PGE bills I added kwh for the month and total is 3650kwh for 10 months. I thought most ppl have Elec. charge around $100 per month. We have AC and used it all time . So it's not like we are cutting on anything. With $1200 a year in Elec. bill, system will break even in 5 yrs. ( After rebate $6050). so it is still cheaper in longer run w/o including rate hike from PGE. Am I doing something wrong ?
 

SoCal Dave

Member
Jul 30, 2020
420
317
California
Yes... From all 10 PGE bills I added kwh for the month and total is 3650kwh for 10 months. I thought most ppl have Elec. charge around $100 per month. We have AC and used it all time . So it's not like we are cutting on anything. With $1200 a year in Elec. bill, system will break even in 5 yrs. ( After rebate $6050). so it is still cheaper in longer run w/o including rate hike from PGE. Am I doing something wrong ?

Nothing wrong as long as you have done the math. In the past solar made the most sense for power hogs such as myself as there was a lower cost per watt for a larger system. Tesla has changed that thinking with their $1.49 / W.
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,871
9,879
Riverside Co. CA
Yes... From all 10 PGE bills I added kwh for the month and total is 3650kwh for 10 months. I thought most ppl have Elec. charge around $100 per month. We have AC and used it all time . So it's not like we are cutting on anything. With $1200 a year in Elec. bill, system will break even in 5 yrs. ( After rebate $6050). so it is still cheaper in longer run w/o including rate hike from PGE. Am I doing something wrong ?

I would imagine that, in the subset of "people on this section of TMC" $100 a month for electric from PGE sounds low (really low), especially if you have AC and use it. My 3 ton builder grade AC unit(s) (I have 2 actually) use 4kWh's an HOUR of power. This means if I run one of my AC units for a single hour, it uses about the same amount of power as your home is using for 8 hours (rough calc, 360 kWh a month divided by 30 days, = 12kWh a day).

Since I have 2 units, running both of them for an hour is 8kWhs, or as much as your home consumes over a 16 hour period.

My ACs are not efficient, but my home itself is pretty efficient, and my average daily electrical usage is about 25-27 kWhs, when not using AC. I am in SCE territory, not PGE but PGE is more expensive than even SCE I think.

TL ; DR $100 a month sounds very cheap for electricity usage, especially for anyone who is hanging out in this section of TMC, I would think, lol.
 

Hay2000

Member
Sep 1, 2020
33
11
ca
Okay... thank you all for your input. Hopefully 4kw is enough to add one plug-in hybrid with current usage. Soon will know.
Expected to get permit in a week or so and Advisor said Installation could happen within a week after that. crossing my fingers..
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,871
9,879
Riverside Co. CA
Okay... thank you all for your input. Hopefully 4kw is enough to add one plug-in hybrid with current usage. Soon will know.
Expected to get permit in a week or so and Advisor said Installation could happen within a week after that. crossing my fingers..
Welcome to the TMC energy section, btw!
 

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