Driving on Sunshine

[Electricfan]

Why would you do that instead of charging at night?
Is your solar system not grid tied?
Is the price per kWh the same at mid-day as it is at 1 am?
Even if it is, I think it's better for the environment for grid usage to be lower during the day and higher at night; the flatter the grid's energy usage, the better.

Is your solar system not grid tied? Yes, its grid tied.

Is the price per kWh the same at mid-day as it is at 1 am? Yes, until the 19th when my "free nights" plan kicks in. After that I will be charging at night.

better for the environment for grid usage to be lower during the day - yes I agree. I'm not getting paid for the power I export right now, so I didn't want to export any. Selfish!!! I signed a surplus power agreement with Centerpoint and it will go into effect in 45 days they said. But my free power at night plan with TXU starts the 19th, so I'll be charging exclusively at night starting then.

 

[derekt75]

Is your solar system not grid tied? Yes, its grid tied.

Is the price per kWh the same at mid-day as it is at 1 am? Yes, until the 19th when my "free nights" plan kicks in. After that I will be charging at night.

better for the environment for grid usage to be lower during the day - yes I agree. I'm not getting paid for the power I export right now, so I didn't want to export any. Selfish!!! I signed a surplus power agreement with Centerpoint and it will go into effect in 45 days they said. But my free power at night plan with TXU starts the 19th, so I'll be charging exclusively at night starting then.

not getting paid for power that you export?
I hate it when government agencies incentivize people to do things that are not in the best interest of the people or the environment.

 

[miimura]

not getting paid for power that you export?
I hate it when government agencies incentivize people to do things that are not in the best interest of the people or the environment.

In many countries, there is no Net Metering. There is a consumption meter and a generation meter. Billing is completely separate on the two meters. The generation meter gets paid off of a Feed-In Tariff. In Germany for example, they gave long term contracts with favorable feed-in tariffs so that you could get a bank loan and there was guaranteed return on the system. They have been steadily ratcheting down the feed-in tariff rates over the years. However, this means that someone who has had solar for several years may be earning more than double what you would on a new system and they will continue to be paid that high rate until the end of their contract. Other countries have a fixed low feed-in tariff of like 5 cents/kWh and retail electricity prices of about 15 cents/kWh. In this situation, it is beneficial to use your own generation as much as you can because the utility will be selling it to your neighbor for a tidy profit.

 

[adiggs]

In many countries, there is no Net Metering. There is a consumption meter and a generation meter. Billing is completely separate on the two meters. The generation meter gets paid off of a Feed-In Tariff. In Germany for example, they gave long term contracts with favorable feed-in tariffs so that you could get a bank loan and there was guaranteed return on the system. They have been steadily ratcheting down the feed-in tariff rates over the years. However, this means that someone who has had solar for several years may be earning more than double what you would on a new system and they will continue to be paid that high rate until the end of their contract. Other countries have a fixed low feed-in tariff of like 5 cents/kWh and retail electricity prices of about 15 cents/kWh. In this situation, it is beneficial to use your own generation as much as you can because the utility will be selling it to your neighbor for a tidy profit.

As I understand it with the feed-in tariff, part of the story with your neighbor who put their system in earlier, is that they also installed it when solar was more expensive to install. They might be earning double; they might have also spent double.

Not saying this to be argumentative - just to include some of the additional context.

 

[liuping]

My 13 additional panels came online yesterday, so now my Model S is covered by solar.

I added enough to cover approximately 17kWh per day, which is my average changing amount since getting the car last November.

 

[miimura]

As I understand it with the feed-in tariff, part of the story with your neighbor who put their system in earlier, is that they also installed it when solar was more expensive to install. They might be earning double; they might have also spent double.

Not saying this to be argumentative - just to include some of the additional context.

Clearly the install cost was different and I thought it was so obvious that I didn't say it. The fact remains that the utility is currently paying drastically different prices to different producers just so that they can make good on the original agreement. From a historical standpoint, the feed-in from years ago may have been equivalent to or possibly even higher than the retail electricity rate, while today it is well below the retail price. You can make a variety of arguments about the ongoing viability of Time-of-Use Net Energy Metering from the utility perspective, but from a customer perspective it makes a lot more sense to pay for what you use when you use it. It also makes a lot more sense than the obvious subsidy that the German Feed-In structure embodied in the early years.

 

[mknox]

As I understand it with the feed-in tariff, part of the story with your neighbor who put their system in earlier, is that they also installed it when solar was more expensive to install. They might be earning double; they might have also spent double.

Not saying this to be argumentative - just to include some of the additional context.

This is the very argument used in Ontario, Canada as the FIT rates go down. The idea was to guarantee a specific payback period and so the contract FIT rate drops as the cost of new equipment falls, keeping the reduced payback window the same. Seems fair to me.

 

[Robert.Boston]

Clearly the install cost was different and I thought it was so obvious that I didn't say it. The fact remains that the utility is currently paying drastically different prices to different producers just so that they can make good on the original agreement.

That's how contracts work. The price in the future may rise or fall, but the contract pricing terms are unchanged. Doing anything else would have very bad impacts on the willingness of anyone to make a long-term capital investment.

 

[miimura]

That's how contracts work. The price in the future may rise or fall, but the contract pricing terms are unchanged. Doing anything else would have very bad impacts on the willingness of anyone to make a long-term capital investment.

I understand. That is the point of the scheme - to drive adoption with a guaranteed payback given the costs at the start of the contract. However, it still seems strange to me for someone, presumably the government, to place the burden of costs on the overall tariff structure and therefore the ratepayers as a whole in order to fund the costs of the scheme. I think that's why you don't see this particular incentive structure in the United States. California had a very lucrative solar rebate program (~$3.00/W IIRC) when system costs were higher and they ramped down as the installed base grew. The PG&E territory has completely exhausted its allocation of rebates, yet people still find it attractive to install PV solar in that area. This may be naive of me, but I don't think the rebate funding in CA had any direct effect on general utility ratepayers.

 

[dhrivnak]

Here is my year update with our 7.1KW solar system. In NE Tennessee we produced 10.1 MWh or an average of 27.6KWh/day. This matched up well with our average daily use of 28.4KWh/day. We offset 97.6% of our usage, including about 700 miles/month of driving. The system has also made me appreciate the grid more as I only used 25% of the power when I was producing. For the most part my meter ran backwards during the day and then forward at night. But the biggest advantage of the grid is during the wither when we heated more (Heat Pump) and produced less we ran a 1700KWh deficit. This spring and summer we make up 1400KWh of that deficit. With our power company we get to "bank" that excess production and I am betting we will likely offset more than 100% of our usage going forward. The system was not inexpensive at a net cost of $18,000. But now with a modest power bill of $7.21/month I should be set for the next 30 years.

I am also hoping to revive the thread to see if we can get at least 200 votes. We seems to be holding above 55% of Tesla owners who have take the solar plunge.

 

[Robert.Boston]

Thanks for the report and update. It's great to see these sorts of statistics. Value of a grid connection is too often undervalued. It sounds like a win win situation, too, because your utility needs the summer daytime power more than it needs winter nighttime power.

 

[dhrivnak]

I finally got around to putting some of the details of our solar system on the web. Solar PV

I am open to any feedback you may have. In the first year I generated 10.1 MWh which matched nicely with our 10.2 MWh usage. I will be preparing for a session at the East TN environmental conference and hoping I can use a few shots of people's home systems that have been posted here. I am working hard to get people to consider the combination of solar and EV's.

 

[Chipper]

I finally got around to putting some of the details of our solar system on the web. Solar PV

I am open to any feedback you may have. In the first year I generated 10.1 MWh which matched nicely with our 10.2 MWh usage. I will be preparing for a session at the East TN environmental conference and hoping I can use a few shots of people's home systems that have been posted here. I am working hard to get people to consider the combination of solar and EV's.

Tell me what you would like and I will gladly provide what I can from my 10kW system.

 

[dhrivnak]

Tell me what you would like and I will gladly provide what I can from my 10kW system.

Thanks ideally I would like a picture of your car with the solar in the background along with the % of power your system provides. You can post here or email at [email protected]. thanks.

 

[DFibRL8R]

dhrivnak (or anyone else who knows),
I am considering the Sunny Boy SMA inverter for an upgrade to our existing solar system (adding 26 new panels). I am interested in the 1500 watts available backup power for grid outage and see you have used this to charge your roadster. Does anyone know if a Model S will charge off of this backup outlet? Obviously I could dial the amps down on the Model S but does the S not like the voltage fluctuations that you might see on a partly cloudy day? Would love to hear from someone who has successfully used this set-up to charge the Model S prior to investing in this inverter.

 

[dhrivnak]

dhrivnak (or anyone else who knows),
I am considering the Sunny Boy SMA inverter for an upgrade to our existing solar system (adding 26 new panels). I am interested in the 1500 watts available backup power for grid outage and see you have used this to charge your roadster. Does anyone know if a Model S will charge off of this backup outlet? Obviously I could dial the amps down on the Model S but does the S not like the voltage fluctuations that you might see on a partly cloudy day? Would love to hear from someone who has successfully used this set-up to charge the Model S prior to investing in this inverter.

I only charged for an hour and it was mostly sunny but did have some clouds. I think it compensates by being very conservative as it limits my 4000 watt inverter to 1500 watts. So as long as the panels are putting out above 40% you are good. A big cloud could knock your car off line I would guess.

 

[Daniel Scherer]

 

[dhrivnak]

Nice shot, I hope others can post a picture of their car and solar system. I have another presentation coming up on the green economy.

 

[dhrivnak]

Trying to give the poll a boost as we now have many new members. I am trying to determine how many Tesla owners have also made the jump to Solar to complement their EV. So please log your vote and if you do have solar please post a picture of you car with your solar if you have one.

Thank you.

 

[bollar]

I'm surprised that I never posted a picture of the car with the panels...

The system pictures are earlier in the thread here: Driving on Sunshine - Page 8