Buying House with Tesla

[chrisski]

I typed a little misleading. I don’t have an EV, but am leaning to get a Nissan Leaf.

[Ampster]

I’ve always assumed the charger inefficiencies were built into the numbers I’m pulling for a Nissan Leaf like 3 miles per kwh. I hope I don’t need to throw in another 11%-15% charging inefficiencies.

I guess it would depend on where the kWhs that are going into your Leaf are measured? I have ways to measure the kWhs going into my charger and presumably the kWhs going into the battery pack but I have never coorelated the two because from the perspective of the EV I think in terms of miles of range added.

[chrisski]

I’ve always assumed the charger inefficiencies were built into the numbers I’m pulling for a Nissan Leaf like 3 miles per kwh. I hope I don’t need to throw in another 11%-15% charging inefficiencies.

[Ampster]

What is the lowest amps you can charge your EV with on level 2?

I think it depends on the onboard charger. One of my cars lets me set it at 5 Amps. The other one only goes down to 12 Amps. I am sure it probably varies by manufacturer and by the capacity of the onboard charger.

I suspect the efficiency is related to the fixed overhead of the onboard charger and the lower the kWhs going in the lower the efficiency. There may be efficiencies related to the higher voltage as well but that is just speculation.

[chrisski]

No, Level 2 is only available from 240 volt service. The efficiency I quoted was for the onboard charger. You would have to add inverter inefficiency to that.

What is the lowest amps you can charge your EV with on level 2?

[Ampster]

Is level 2 available with only 1800 watts to the inverter from a 120 volt inverter?
......

No, Level 2 is only available from 240 volt service. The efficiency I quoted was for the onboard charger. You would have to add inverter inefficiency to that.

[chrisski]

Level 2 charging is more efficient than Level 1 if that matters to you. 89% vs 84% respectively.

Is level 2 available with only 1800 watts to the inverter from a 120 volt inverter?

I did not think level 2 charging was available using a mere 1800 watts from the 120 volt inverter. The two inverters I have are both 120 volt.

=============================================

I did not use inverter inefficiencies in my calculations above, so I will change it to:

My planning numbers are to use 13 amp level 1 charging for an EV from a 120 volt inverter. That is 1560 watts per hour from the inverter with an 85% efficiency and 1835 watts per hour from the batteries and or solar panels' SCC. At 3 miles per kWh, that comes out to 4.68 miles of charging per hour or 8.54 hours per day . Level 1 charging those vehicles for 40 miles (20 miles each) per day would use 15.69 kWh, leaving an 17 kWh system 1.3 kWh to run everything else.

1.3 kWh is plenty for my RV for most days, but any cold day I desire to use the heater, that could bring my consumption to 2.2 kWh, so that would not be enough power on those freezing winter days.

[Ampster]

.......
I don't have an EV, but am planning on getting one. My planning numbers are to use 13 amp level 1 charging for an EV. That is 1560 watts per hour and at 3 miles per kWh, that comes out to 4.5 miles of charging per hour. Level 1 charging those vehicles for 40 miles (20 miles each) per day would use 13.3 kWh, leaving 3.7 kWh to run everything else. Those planning numbers may be off a little and are designed for a Nissan Leaf not a Ford Lightning pick up or Riva SUV..,......mm

Level 2 charging is more efficient than Level 1 if that matters to you. 89% vs 84% respectively.

[chrisski]

@ Mike - Seller says 2 cars are powered by it in addition to the whole house, does that sound incorrect? You say its small output, and I agree based on the kW specs listed on the Tesla site, something doesn't add up here.

To maintain any reasonable level of comfort, and charge two vehicles that are both driven 20 miles a day, I would say a 2.65 kw system falls well short of what you need.

I have a 2.55 kw system on my RV, and I can make enough electricity to run a 1800 watt load for about 6 to 8 hours. I have topped out at 16 kWh production in a day. The system you have is only 100 watts bigger, so perhaps 17 kw power a day in my area in April.

I don't have an EV, but am planning on getting one. My planning numbers are to use 13 amp level 1 charging for an EV. That is 1560 watts per hour and at 3 miles per kWh, that comes out to 4.5 miles of charging per hour. Level 1 charging those vehicles for 40 miles (20 miles each) per day would use 13.3 kWh, leaving 3.7 kWh to run everything else. Those planning numbers may be off a little and are designed for a Nissan Leaf not a Ford Lightning pick up or Riva SUV.

For an RV with gas heat, gas fridge, and no AC, that extra 3.7 kWh is plenty. It is not plenty when your typical electric bill for a 3500 sq ft house is 1 MW per month.

Turn any one high wattage appliance on for any length of time, and that does not work. 20 miles per day per vehicle may not be realistic.

I used to think Air Conditioning was a luxury. Then I moved away from Massachusetts and now think AC a necessity, but heating is a luxury.

[HappyPants]

Thanks for all the advice. Lesson learned is that its a very hot market, the time to scope out facts in the heat of the moment when houses are selling within hours of their listing makes it difficult to make really informed decisions. Its a bummer that the list agent says at the end of the MLS Listing: "DID I MENTION IT COMES WITH PAID SOLAR!!!!

This was deceptive and dishonest.

Its one 2.6kW panel, most likely used for 1 Tesla EV.

Anyhoo, not a big deal, its a sellers market, they have alot of power when houses are going so fast to investment banks.

[J.P.M.]

EXACTLY why he needs to look at the bills. Seller states the solar system covers his usage so the bills should read zero other than the fixed "ready to serve" charges.

Unless the OP lives like he's off grid, there's little likelihood a 2.65 kw systm will produce more than ~4,000 kWh/yr - and that's in a moderately sunny climate.

The bills area result of usage. Usage numbers in kWh are what's used to determine what system size is desired to produce a desired result. The system that meets the criteria (which may be more or less than actual annual usage) can then designed.

Or, in cases like the OP's an existing system of a fixed size can be "rated", that is, it's approximate annual output be estimated and then subtracted from the OP's actual usage. Then, an annual bill can be estimated.

[Mike 134]

Seller says his electric bill is $230 a month,

@ Mike - Seller says 2 cars are powered by it in addition to the whole house, does that sound incorrect? You say its small output, and I agree based on the kW specs listed on the Tesla site, something doesn't add up here.

Well at least you know your hunch was right and his solar system only "offsets" a small portion. Better than nothing.

[HappyPants]

Seller says his electric bill is $230 a month, have not asked for 12 month stack of bills yet, we're in escrow so I'm trying not to be too much of a PITA.

My mortgage will be $400 less than my rent so life is good.

[Mike 134]

The bills will tell you what someone else paid. Depending on the information in those bills, they may or may not be less than helpful. Besides, everyone's lifestyle is different and that difference is why a look at prior bills has limited use.

EXACTLY why he needs to look at the bills. Seller states the solar system covers his usage so the bills should read zero other than the fixed "ready to serve" charges.

[J.P.M.]

Yeah I'd love to see the bills. I guess my big question is, is it possible that 2.6kW sustains 2 vehicle chargers and powers the whole house (1600sqft)

I don't have electric cars, so I don't know what to expect. Seller has had 2 EVs for 3 years I believe. So assume my bills will be marginal.

Thank you as well J.P.M - I appreciate the knowledge nuggets.

The bills will tell you what someone else paid. Depending on the information in those bills, they may or may not be less than helpful. Besides, everyone's lifestyle is different and that difference is why a look at prior bills has limited use.

Bettter to get a PVWatts model output and compare that to your annual usage.

Read the book before tackling PVWatts as one way to begin to get an idea of how to frame that question which might be better asked as:
How much of my electrical load will a 2.6 kW PV system offset ?

The answer depends on several variables. You'll need to understand what those variables are, which of them apply to your situation and in what ways they apply to your situation in order to answer that question.