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cost per charge at home ??
- Thread starter jmanning
- Start date
Reciprocity
Active Member
No, thank you! Trust me I am very torn. I am really into the solar roof. I cant find the link, but what I might do is get some portable panels for the summer months when I use the most electricity with the AC running. Also when the real time pricing is the highest. I cant find the link, but they plug right into your house with a built in inverter and can feed power back. You can also take them camping and plug stuff directly into them with 120v plug. I think they are about 120w and you can daisy chain more then one of them together.
I like the flush mount ones, but I am a bit worried with the pitch of my roof, which faces south, and is 6"/12" pitch or 45 degrees. What is the best angle for the panels and does that change based on your longitude or is it latitude? I believe I have enough room for 5kWh which would almost be enough though I think 6kWh would be ideal.
The simple rule is tilt angle equals latitude (that is what the chart above assumes). The complicated rule is to evaluate your shading patterns, your electrical usage, the cost of power at various times and seasons, your local legislation on net-metering, your local electrical peak times,...
However, the differences aren't great, and usually don't override the simplicity of mounting them flat to the roof. 45° should be fine in the continental US.
Thank you kindly.
Reciprocity
Active Member
Thanks again.. yeah it looks like 45 is best for winter, but 21 for summer. I use under 1kW per day in the winter and up to 1.6kW per day in the summer. Am I way off thinking I need 5-6kWh based on sunny hours during the day, but maybe I dont need so big of a system being that the biggest spikes I have are during the times when the panels will be the most efficient, hot summer days.
That's great, but the price of panels has dropped since then (yes, since Nov 2015). The difference in cost between adding the necessary infrastructure to make the perfect angle (or a variable angle), and just adding a few more panels is likely to fall far on the just add more panels side. Unless you are planning on building a new house (in which case, optimize away), just get them up there.
Thank you kindly.
Ahisaac
Member
I'm on a EV pilot program with Dominion Electric in Northern Virginia. I charge my car during the Super Off Peak period (1-5am @ $.05/KwH). Based on my TeslaFi data, I've charged my car 111 times at home, at a total cost of $151.11 (starting on 9-DEC-16).
Reciprocity
Active Member
I think I only really need 3800kW system so less then I had originally thought. IL does not have a lot of incentives but does have a fairly high rate for purchase of excess electricity generated during the peak hours.
Nice site to determine tax and other benefits by state:
Illinois Solar Power for your house - rebates, tax credits, savings
Size that your roof will support:
Solar Roof Calculator
Not looking for off grid but this was a nice calculator to determine what I would need:
Off-Grid Solar System Calculator
Thanks again for all your help on this. Looks like a 3.8kW system would pay back in roughly 8-9 years so that is not bad. I still want a solar roof though. I will prey for hail this summer and figure it out for next year probably.
Reciprocity
Active Member
That is a ridiculous price, bravo. but does that include both supply and delivery? I was looking at just supply and thought I was only paying between -3c - 4.6c and in reality I was paying bout 10.6c/kWh.
Ahisaac
Member
I don't know about the supply/delivery aspect. Just that I only charge between the 1-5am period at that Super Off Peak rate that's specified in my agreement. It's a pilot plan though and expires in Sept 2018. We're moving, actually building a new home 7 miles north of our location, so this rate will come to an end soon. But, even at 10-12 cents per KwH, we're talking 2-2.25 times more than my my current rate which is still significantly less than than what I was paying in weekly fuel costs as a commuter. At the end of the day, I'm happy with saving some gas money. But, I bought the car for other reasons beyond the fuel savings. That was just a benefit.
SageBrush
REJECT Fascism
Here is a link to the data explorer section of Google Sunroof. Fascinating app that calculates the fraction of roofs in an area that "make sense" for PV.
I looked at the greater San Diego, CA area and note that the app uses 1.35 kW/watt*year as a threshold generation. Presuming utility rates of 20 cents a kWh and 25 years of full generation and a 30% federal rebate, that works to an installed cost limit of $9.64 a watt. I'm pretty sure that installation costs in that area are below $5 a watt, so Google is being quite conservative.
Or put another way: at $4.8 an installed watt, PV electricity is no more than 10 cents a kWh in this area before TOU arbitrage sweetens the deal for 90+ percent of roofs.
I looked at the greater San Diego, CA area and note that the app uses 1.35 kW/watt*year as a threshold generation. Presuming utility rates of 20 cents a kWh and 25 years of full generation and a 30% federal rebate, that works to an installed cost limit of $9.64 a watt. I'm pretty sure that installation costs in that area are below $5 a watt, so Google is being quite conservative.
Or put another way: at $4.8 an installed watt, PV electricity is no more than 10 cents a kWh in this area before TOU arbitrage sweetens the deal for 90+ percent of roofs.
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I have to correct what I said earlier about my average energy use in terms of equivalent cost per mile for a gasoline car.
Today I happened to look at my cumulative electric use over the winter.
According to the car, I used 1,346.5 kWh to drive 3613.8 miles over the 4-month period, for an average of 373 Wh/mi.
Looking at my electric meter, the total consumption over the period was 2096 kWh.
At first, the difference (between what the utility reported and what the car reported) of 749.5 kWh startled me. I did not think that the conversion inefficiency of the on-board AC-Dc converter could be that bad!
But then I realized that a large portion of this is probably preheating of the car on cold days. As I understand it, the energy used for preheating (or precooling) is not included in what the trip meter reports, so long as the preheating occurs while the car is plugged into the charging circuit.
(I also have a security lamp on the same service, but nothing else. The lamp is operated by a motion sensor, has 2 standard incandescent floods, runs for about 15 minute if actuated, and has actually been turned off entirely since early March. But even if I assume it was on every day since November 25 for 1 hour a day (which it wasn't), that is only about 24 kWh.)
Since we have to pay for the energy we buy, not just what the car reports as used for propulsion, the actual cost is the 2096 kWh the meter reported for 3614 miles, or 580 Wh/mile. That is less than 2 miles per kWh, much less than the "rule of thumb" of 3 miles/kWh mentioned in some of the posts in this thread. At 18.4 cents/kWh, that implies a running cost of 10.7 cents/mile. Contrary to what I said earlier, that is equivalent in cost (only) to regular gas at 21.7 mpg or premium gas at 25.5 mpg. Not so great! (Roughly equivalent to what i was getting in the Mercedes E-class I used to drive, actually.)
So I will need to think more about how to answer the question about how my energy use compares to a fossil-fueled car, especially in winter. Between conversion losses and preheating, I do not think I can make any kind of economic argument based upon running costs.
I live in the Boston area, which is much milder than most of Canada or even northern New England. So the numbers would be much worse for the upper Midwest or other cold regions. (This would be better in the warm weather, of course.)
Reciprocity
Active Member
I checked here first but not available yet in my area. They havnt mapped my area yet I dont think.
EV-lutioin
Active Member
MikeBur
ManualPilot
No data is safe from hackers. More appropriate question might be "should I trust TeslaFi's competency to use my username/pw appropriately and do their utmost to not keep my credentials?" As much as I can, Yes. I see them generate a token and reuse that token to my TM account, and it needs refreshing manually.
In terms of keeping the data generated safe? It's SSLd, though I don't hold such a thing in high regard - there's easier ways for the capable to track you and your movements ;-)
Edit: I see you posting same question elsewhere on tmc. You might want to just chat directly via PM to the creator James via @Jdeck iirc
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MikeBur
ManualPilot
Fine. No datum IS safe and no consolidation of data ARE safe
Didn't realise the grammar police were out in force today ;-)
You are correct, sir, however:
"it is increasingly common to use “data” as a singular uncountable noun, [...] in the same way as “information” – is now generally accepted in everyday English, so much so that using the word as a plural countable noun can sound incorrect." (Reference)
dgpcolorado
high altitude member
I suppose it depends on how one chooses to think about it. My panels are not cost-effective on a payback basis, in part because my system is too small — 2170 W — for economy of scale and also because I installed panels early on when they were much more expensive than today. But that doesn't matter to me because I budgeted them as part of the cost of an electric car. So, no, I don't pay for electricity, beyond the monthly service charge that everyone here pays for maintenance of the grid. The panels are a part of my EV purchase. That they also generate enough electricity to run my house is a bonus.Well, youk now this, but you still pay with solar. You paid for the solar installation and materials, thus you are still paying for that electricity, though probably cheaper than the utility company.
Lest people think that's not a fair way to look at it, I will point out that many, perhaps most, folks here paid more for their Tesla(s) than I paid for mine plus the cost of my solar panels. Yet they don't have to justify the cost and I do?
When I bought my panels my view was that "people buy less useful toys [than my panels], do they not?" For some reason, however, the installation of solar panels has to pencil out on a payback basis. Why? I have neighbors with very expensive hobbies such as golf or foreign travel yet those don't have to pay for themselves. I have solar panels and an absurdly expensive — even though purchased as CPO — Model S, so that I can "drive on sunshine" because I enjoy it! Simple as that. So long as I can afford them, that's enough justification for me.
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