Prius Prime 2017 - Comparing Electric vs Gas cost

I am not sure in AZ, but in my state the public utility is regulated by state, so it is published in .gov home page. Even if it is private utility, it should be stated clearly somewhere in you bill.

I think OP of the 4 cents/kWh generate his own electricity on PV. My public offering electricity rate is currently $18.1/kWh, but I am paying extra for renewable energy source, so it cost more. Electric rate just as gas price seems to vary widely depending on where you live from a few cents to upward of 40 cents per kWh from what I have read here in Prius Chat.

Here is my post in different thread showing someone's spreadsheet for comparing EV vs. HV cost.
Prius Prime as 2nd car? | Page 2 | PriusChat

 

I've said it before and I'll say it again. You HAVE to include the "fixed charges" because they are included in gasoline. You have to pay them so you have to include them. If you don't you're just fooling yourself.

 

Yes, and no.
If the 'fixed charges' are charged by the kWh delivered, yes, you should include those.
For fixed charges that are truly fixed, no you shouldn't include those as you pay them whether or not you are charging a car. Charging the car doesn't add any fixed costs.

In my case, I am using solar and have a flat rate "service charge" as well as delivery charges and such based on the kWh I use.
So I don't include the flat rate, as it would be there regardless of having an EV or not.
The per kWh charges I include, however since I am on net metering, most moth

 

Sorry for being dense about this 5.x kWh. Perhaps @Oniki:

When I look at the Prius drivetrain, I see:

• A - 100% of the charging power input to the house wiring as charged at the meter.
• B - ~90% boost converter generating DC charging power plus house wiring loss
• C - ~96% LiON battery efficiency
• D - ~90% boost converter and motor generator drive efficiency
• E - ~94% reduction gear and differential efficiency, 2% per stage
• F - ~95% tire and wheel bearing efficiency

These efficiency numbers per stage came from various Googled sources. I am OK if someone has better metrics. Now we can calculate the kWh at each stage:

	Stage	Eff. %	kWh in	kWh out	source
1	A	100%	6.3	6.3	Service meter
2	B	90%	6.3	5.7	Charger 2013 PiP INL
3	C	96%	5.7	5.4	Battery 2013 PiP INL
4	D	90%	5.4	4.9	Drive and motor Est. 2013 PIP INL
5	E	94%	4.9	4.6	Gear 2% per stage
6	F	95%	4.6	4.4	Tire rolling drag

Idaho National Lab (INL) does field tests of various cars including the 2013 Plug-in Prius: https://www.energy.gov/sites/prod/files/2015/03/f20/fact2013toyotapriusphev.pdf

So @Tideland Prius and @Oniki , where is your '5.x kWh' come from?

The other curiosity, what does this help us understand?

I have to pay the utility company for my electrons so I'm trying to understand what insights we gain from tracing the internal energy flows that with very few exceptions, we have little control.

Bob Wilson

 

BTW, the best estimates I've seen for any kind of renewable energy (solar, wind, etc) with a 10kWH battery is around $15k USD.

(I honestly don't know if that's how much is available per hour, per day, or what?)

If the Prime takes 6.3 kWH to charge, then at my current rate of about $2.80 per charge, the break-even on a solar or wind power source just for the car is 5400 charges! If I charge it daily, that's 14+ years.

That does not make sense to me.

 

14 years payback for a house solar panel is pretty good IMHO. I have seen 30 years or more even in the best scenario, and many actually never recover initial cost. If you do it for purely economic reason, many "eco" makes no sense.

 

If you had used 261 kWh of electricity, how much would your bill have been ?
(Hint: it is not $58.22)

 

It shouldn't.
You are comparing Apples to Fig Newton wrappers

 

NO NO NO NO

You do have to pay fixed charges, but in any place I know of they are billed separately for residential electricity.

 

If he was saying that a 10 kW system costs $15k then $1.5 per watt

A watt typically produces somewhere in the range of 1.5 - 1.8 kWh a year depending on geography, siting etc
A panel is estimated to produce for about 30 years
So the $1.5 investment is good for about 50 kWh

The $1.5 watt investment is paid off (and electricity free afterwards) when enough kWh have been collected to equal $1.5. This depends on the alternative cost of electricity. Presuming a watt generates 1.65 kWh a year,

	Cents Per Kwh	Cents Saved per Year	Free after (Years):
1	10	16.5	9.09
2	12	19.8	7.57
3	14	23.1	6.50
4	16	26.4	5.68
5	18	29.7	5.05
6	20	33.0	4.54

 

So you guys are still fooling yourselves about your real electricity cost. Keep it up. I'm ignoring your claims of saving. If you buy gasoline those "fixed costs" are built into the pump price, and you are then comparing "apples to oranges" when you ignore them with your electric bill.

I hope those with solar are not thinking their electricity is free, because it is not. Amortize the cost of the infrastructure (panels, regulator, batteries, etc.) over the life of the system and its' parts when any fail, divide by the power you get and use over that time and that is your cost per kw-hr.

From the data presented in this topic it appears running on EV is about half the cost of running on gasoline at this time.

I just received a mailout from the Alberta govt. on our electric rates. They do, of course, vary all over the place (we pay "market price"). Nice graph, with a high of about $0.15 to a low of about $0.028 per kw-hr. The low occurred last fall, the high in 2012, when everyone was "ripping off" the people of California.

We pay a "carbon tax" on gasoline and we have been told what that rate is by the current left wing govt. There is also a "carbon tax" on electricity, put on in secret by a previous right wing govt. We are not told what that rate is. More "alternate facts".

 

Have you ever wondered why petrol is not priced like electricity ?

For example,
$20 to activate the pump,
Then $1 a gallon

The main reason is that most of the cost of petrol is the oil itself and not the infrastructure.
The reverse is true for electricity so the infrastructure is billed separately.

 

I am not following your calculation, but that's OK. There are way too many assumptions made, that may or may not valid for particular situation. I just know, for one analysis I had done on my property, one solar company gave me a figure of $45,000 to install large enough PV to cover our needs, and 17 years for payback period. This is assuming that there is no drastic changes in current electric rate, and the system will operate trouble free without any additional cost for repair or such. I don't see this as a good investment. Then again, home ownership is never a good investment IMHO.

 

What is unclear ? Point out the specific steps that are confusing

 

First, I am not sure how big a system you are talking about. I’m a little confused if the quote is for a 10kW array with a battery, or an array of unknown size with a 10kWh battery.
In any event, a battery is not required if you use the grid as a battery.
Also, keep in mind any rebates and incentives.

Here is how I calculated my costs:

S = Annual solar production in kWh
C = Initial total cost
R = Replacement cost of Inverters
Government Incentive = C x 30%
Production incentive = 10 x (S x $0.08) *provided by utility
Net Metering Incentive (only if at the end of the year more kWh is sent to grid than used)= Whatever utility pays for any over-production
T = Total energy expected over life of panels

T= 90% x (30 x S). <I used 90% to be conservative>
Total net cost = (C + R) - (Government Incentive + Production Incentive + Net metering Incentive)

I then divide T by Total net costs to get my price per kWh.

You could include costs for a battery, higher or lower production, etc.

This, to me seems the most fair and accurate way to do it.

 

I think you mean total ENERGY expected over life of panels

 

I am not saying you are wrong or your calculation is unclear. I am just saying the assumption is not valid for my situation, and the payback period you indicated would not apply to me. For example the OP's 10KW system for $15,000 is way lower than my quote for my local. Maybe OP's area has much better incentive than us. That's all.

 

Perhaps you should keep shopping;
Or learn how to put some 'sweat equity' into a system.

In my corner of the world a group has arisen that organizes neighbors to help each other put up PV. They end up paying about $1 a watt after tax credits. And now you know, that works out to be about 2 cents a kWh over the array lifetime. Even at a cost of $4 a watt -- which I think defines the expensive end these days -- it works out to 8 cents a kWh

 

Yap, that's the plan for now. Probably starts at smaller system than whole house need and DIY.