Solar Charging an EV

[dpeilow]

Yep. It's an eye opener.

In the UK you would need a 3.5 kWp system to get 12,000 miles - but with current solar prices that could still come in at £6000.

 

[dpeilow]

I did my personal version.

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[Robert.Boston]

Suggestion: do this in Net Present Value terms. The difference will be smaller, but it will also be actionable.

 

[vfx]

http://www.solarworld-usa.com/solar-for-home/solar-home-gallery/mcmurray-residence.aspx

 

[PV-EV]

With the recent development of the OVMS it will be possible to directly utilize PV power for charging your car. I have an off grid system but a similar approach would work for grid tied systems as well. The idea is simple. PV output is monitored with an XBee radio. The XBee has an analog to digital converter. This data is radioed to another XBee connected directly to the OVMS. The OVMS will look at the power available from the PV and start/stop charging and/or adjust the charge rate accordingly. The radio that is monitoring the PV output would need to be within range of the car in order for the signal to be received - not a problem in my situation. I'm not sure just how fast the car can change charge rates but I think it would be on the order of a few seconds. While this is not perfect, it will be fast enough to account for intermittant shading from clouds and changes in sun angle and intensity. Now that I have my OVMS installed and working I will begin to work on the hardware interface for the radio and the software required to make it all work.

 

[dadaleus]

San Diego Gas and Electric is lobbying to start charging net metering solar homes for their use of the grid, in both directions, nearly eliminating any power bill savings from having solar. Their argument is solar users still put stain on the system causing others to have to pay the maintenance costs for solar owners' usage. This arguement must have some truth, but I can't image the costs are as high as the proposed rates imply, not to mention the public good aspect of generating clean solar power during peak periods. I suspect there is a big judgement call involved in how one models this and attributes costs.

Anyway, if they manage to get something like this through, it will certainly make local storage a lot more appealing.

 

[Lloyd]

Yes, this will make more people want to be off their grid. Make the rates more reasonable or people with elect not to use their service. Next they will mandate you to have and pay for electric service!

 

[vfx]

San Diego Gas and Electric is lobbying to start charging net metering solar homes for their use of the grid, in both directions, nearly eliminating any power bill savings from having solar....

That's as outrageous as the EV road tax!

 

[Robert.Boston]

That's as outrageous as the EV road tax!

I disagree. If you are buying and selling across the utility grid, you should contribute to the cost of building and maintaining that grid. If you have balanced usage, that is very different than saying you have no usage. If I drive round-trip across a toll bridge, I still pay the toll bridge both ways -- I don't get my money refunded for driving back across.

The serious policy question is the rate to charge. Personally, I think the cost of interconnecting a residence should simply be a flat charge, not usage based. The "wear and tear" from usage is minimal; it's mostly physical aging and catastrophic failures (tree limbs, etc.) that drive distribution costs. Furthermore, there should be some assessment of transmission cost savings from having distributed solar on the system, placing less load on the transmission and deferring expansions.

 

[Kevin Sharpe]

gerber energie systeme :biggrin:

 

[dadaleus]

Robert, everything you say seems totally sensible to me. Like I said, my issue was with the degree of costs allocated. A flat fee would seem quite sensible.

BTW, vfx, I hate to say it, but I do understand the eventual need for an EV road tax (or any non-road taxed fuel vehicle).

In both cases however, I think the public good of encouraging adoption means we, as a society, should delay these as long as possible. It takes a pretty significant percentage to materially effect the economics of the system. e.g. If only 1% of cars are EV, then it's not really affecting wear and tear of roads enough to matter. But 20% would make a pretty big difference so somewhere between those two it is necessary to start having EV drivers help pay to maintain the roads. This is basically the same problem faced by utilities. I'm not sure what percent of electricity is being produced by private solar at this point, but I'm guessing it's still pretty small.

 

[dpeilow]

Here's the Ampera charging on our 9.1kWp solar array.

It was generating over 7.5kW at the time I took the photo, while the car was set to 6A - so we could have been topping up six of them.

 

[Jason S]

I disagree. If you are buying and selling across the utility grid, you should contribute to the cost of building and maintaining that grid. If you have balanced usage, that is very different than saying you have no usage. If I drive round-trip across a toll bridge, I still pay the toll bridge both ways -- I don't get my money refunded for driving back across.

The serious policy question is the rate to charge. Personally, I think the cost of interconnecting a residence should simply be a flat charge, not usage based. The "wear and tear" from usage is minimal; it's mostly physical aging and catastrophic failures (tree limbs, etc.) that drive distribution costs. Furthermore, there should be some assessment of transmission cost savings from having distributed solar on the system, placing less load on the transmission and deferring expansions.

Buying off the grid is already included in the cost of the building, afaik. And if it isn't, then what makes a home solar system different from pure purchaser?

Selling to the grid... what is the typical cost per kwH for the usual small scale energy producer? Are they charged at all? I was not aware of a cost outside of the normal infrastructure costs to connect a purchaser.

I guess my real question is: are residential solar producers being treated fairly now, or not? If not, then does the San Diego proposal shift the treatment to be more or less fair?

 

[dpeilow]

Please keep this thread on topic. There are plenty of others for general solar tarriff discussion.

 

[jcstp]

do not know if this was already on here

Total Solar Solutions | PowerFilmSolar.com

 

[Robert.Boston]

Are there any hardware/software solutions that allow you to pace the charge to your EV based on the availability of surplus PV power? This could matter if the price paid to buy power is higher than the price at which you can sell surplus back to the grid.

 

[jcstp]

Are there any hardware/software solutions that allow you to pace the charge to your EV based on the availability of surplus PV power? This could matter if the price paid to buy power is higher than the price at which you can sell surplus back to the grid.

i know one manufacturer working on it!

 

[PV-EV]

Are there any hardware/software solutions that allow you to pace the charge to your EV based on the availability of surplus PV power? This could matter if the price paid to buy power is higher than the price at which you can sell surplus back to the grid.

I'm currently working on such a system using the OVMS. The idea is quite simple. I measure the output of the array through a DC shunt and radio the data to the OVMS which adjusts the current to the car in real time. My system is off grid but it makes no difference really. A current sensor could also be used on the AC line from the array (after the inverter) for grid tied systems. I'll be using XBee radios and some custom functions in the OVMS code.

 

[JRP3]

http://www.sunnev.com/

 

[MarkR]

I've had solar PV systems at my office for 4 years and at home for the past year. Given that Tesla estimates that the S will require 300Wh/mile driven, and the average driver puts 15K on their vehicle per year, I'm estimating that my energy need for the car alone to be 4,500 kWh per year. In light of the efficiency of my current PV system at home, I would anticipate the need to add 10-12 panels to the home system to cover just the car's needs. Different environments will yield different results. Arizona gets a lot of sunshine, but the intense heat can compromise panel efficiency in the middle of the summer. (actually, I'm developing excess capacity at the office, so the EV will get charged there, but for the purpose of discussion, I've offered this info).