[volton]

Hi all, I'm a new member but have been avidly reading the posts.

I started thinking about how to build a small self contained solar charging station for the Volt that I could set up at work. I'm assuming only a AC charging input will be offered (No DC input) so lets concentrate on that.

First we need the solar panels, I'm thinking 300W or so. Then we would need an inverter to convert to AC. Sounds simple, except there is a problem. The Volt will want about 10-15A of current to charge (at 120V). With a 300W panel, we cannot produce that much current. So that means we need a storage system. So now we have added external batteries into the system to store the solar power and then deliver to the inverter/Volt

There is still a problem, we cannot start charging the Volt until the external battery is charged and then once Volt charging happens the external battery will drain quickly. So now we will have a system that is pulsed, in other words it takes time to store the charge in the external battery, then probably a shorter time to release the charge to the inverter/Volt.

From the Volt's point of view, it will see power cycled on and off. This is a duty cycle approach to charging, and sounds quite feasible except I'm not sure how the Volt would react to a cycled power input? I'm guessing if the cycle times are in the minutes category then it wouldn't mind but less than that and the charging circuit might not like it.

your thoughts?

thanks,
Volton

 

[GAtechVOLT]

I’d like to do this as well, some guy solved this problem already by pulling a trailer behind his car with 6m^2 of solar cells. He’s driving his contraption around the world on only solar power.

See: http://www.solartaxi.com/blog/

From the picture on the front page it looks like he’s got a substantial battery under the cells.

Obviously the volts to heavy to drive on the go with solar but it’d be funny if you could pull a trailer with you to charge it wherever you are parked.

Let me know what you come up with.

 

[wtiger]

soalr

I'd say if Nano Solar ever releases solar ply at a cheap price and a 12-14% efficiency simply cut pieces to fit the roof, hood and trunk of the car and apply like a vinyl sticker then use a dv-dc inverter to bring the voltage up to the needed level. I don't see why you'd need an extra battery. It'd work the same way as trickle charging wouldn't it? True you may only get an extra 3-4 miles extra out of it on a sunny summer day under nearly ideal conditions, but if it were inexpensive enough (300-500 dollars) it'd be worth it. Heck if it only gave you 1 extra mile a day average it could pay for itself over the lifetime of the vehicle so long as gas stays expensive. Then there's always the novelty factor.

 

[volton]

I'd say if Nano Solar ever releases solar ply at a cheap price and a 12-14% efficiency simply cut pieces to fit the roof, hood and trunk of the car and apply like a vinyl sticker then use a dv-dc inverter to bring the voltage up to the needed level. I don't see why you'd need an extra battery. It'd work the same way as trickle charging wouldn't it? True you may only get an extra 3-4 miles extra out of it on a sunny summer day under nearly ideal conditions, but if it were inexpensive enough (300-500 dollars) it'd be worth it. Heck if it only gave you 1 extra mile a day average it could pay for itself over the lifetime of the vehicle so long as gas stays expensive. Then there's always the novelty factor.

I don't think in the case of the AC charge input (which is what I was talking about) that a trickle charge method will be allowed. That input will be like a firehose, taking the maximum current at all times. So I think a external storage system is the only choice in that case. Now if Chevy puts a DC input that can be trickle charged, yes then your solar panel with dc/dc converter idea will work. I just don't see them doing that, extra cost, no standards etc.

 

[pennor1]

A better way would be to install about 3KW or solar on the roof of your house. Then connect the system to your local electric utility grid. Sell back the power that you make in the middle of the day to the utility and use utility power at night to charge your Volt. This way you won't need a large set of batteries and the efficiency lost by charging one set of batteries (the Volt) with another set of batteries in your house. In effect you are using the electric grid as a battery.

This sort of system is called net metering. It's mandated in some States, optional in others The actual price paid back to you per kilowatt hour as well as the price you pay at night will depend on local laws and/or the policy of your local electric utility.

 

[volton]

A better way would be to install about 3KW or solar on the roof of your house. Then connect the system to your local electric utility grid. Sell back the power that you make in the middle of the day to the utility and use utility power at night to charge your Volt. This way you won't need a large set of batteries and the efficiency lost by charging one set of batteries (the Volt) with another set of batteries in your house. In effect you are using the electric grid as a battery.

This sort of system is called net metering. It's mandated in some States, optional in others The actual price paid back to you per kilowatt hour as well as the price you pay at night will depend on local laws and/or the policy of your local electric utility.

I agree that would be better if the car was sitting at home. However in this case it will be sitting at work with 9 hours of free sun waiting for me every day (well most days in Texas ). I would like to build a portable generator that can provide some charge. However I would like to have only a small battery. So my question remians, is there any technical reason a cycled power system would not work? It would be like plugging and unplugging the power cord.

 

[volton]

Pennor1

I reread your post and now understand what you were saying about using the grid as the storage medium. Yes I agree that is a better way to get it done. thanks

 

[G35X]

Putting solar panels on the roof of your house becomes more meaningful if you can store the energy they generate for your OWN use. Sending the energy back to the grid is helpful only when the grid capacity is maxed out. Other times the energy is simply wasted. There is no evidence that the grid generators’ output is reduced by the amount little solar and wind generators send back. Actually I think those little generators are nuisance to the grid because of the Ferranti effect.

 

[Texas]

Putting solar panels on the roof of your house becomes more meaningful if you can store the energy they generate for your OWN use. Sending the energy back to the grid is helpful only when the grid capacity is maxed out. Other times the energy is simply wasted. There is no evidence that the grid generators’ output is reduced by the amount little solar and wind generators send back. Actually I think those little generators are nuisance to the grid because of the Ferranti effect.

This is complete BS that you pulled out of your butt (no offense). Sure one house with one panel is a tiny amount. How about you imagine every house with 5 kWs of capacity... Don't worry because when the sun is shining and people are working there is a natural peak of energy demand. Funny how nature works out well for that.

When percentages of solar and wind get high enough there will be a need for more electrical storage (pumped storage hydro, compressed air, new technology batteries, etc.). This is the future so just get use to it. Many people have a great energy resource and they own it right now! Why not use it? If the infrastructure existed (smart grid, net metering, high volume roll-to-roll based solar manufacturing) and the energy policies were geared for this (subsidies, rebates, guaranteed transfer of ownership, utility company ownership and maintenance of solar systems, etc.) then we would be throwing up as much as we could produce. The sun will shine forever and will power your home and the grid very nicely indeed. Using efficient passive and active solar designed houses and efficient appliances and electric vehicles will allow for a standard of living even better than most Americans live today. Cleaner air, quieter streets, less money pouring out of our country, etc. Solar on the house is a great idea and will be very common in the future. Bank on it.

 

[G35X]

Texas, what part of my post is BS? (I think we exchanged our views on this subject in the old forum.)
First of all I am all for the household solar electricity generation. My main point is that with the high-capacity storage device such as the A123 batteries the rooftop solar panels will become more meaningful.

Let’s go point by point…
I hope you agree that:
1) If we can be independent of the grid, so much the better. (Texas, do you work for a utility company?) Americans, especially those who live in the state of Texas, value independence more than anything else. Being independent of the grid means we can be less affected by natural and manmade disasters.

2) Raw solar energy per square meter (approx. 11sf) is about 1kW, somewhere around 0.14kW of which is turned into electricity if the panel is looking squarely at the sun. If you put an array of 10’x20’ panel on your roof (not perpendicular to the sun in many cases) probably you can get up to 2kW of power during six or so daytime hours. So, conservatively speaking we can store some 8kWh of energy into your own storage device while we are at work. Efficiency of solar panels is getting better and better. Mitsubishi electric made an announcement earlier this year that they would start mass-producing panels of 18% efficiency. DuPont and U of D reported that they had reached more than 40% percent, which would free many of us from the shackle of the grid completely if the panel is combined with a high-capacity storage device.

3) AC power distribution system is a two-way street therefore; the Ferranti effect is a nuisance to the grid. Any glitch or spike at the downstream goes back upstream, amplified.

4) Other than the peak hours the grid has plenty of surplus. Take the Caiso, for example, there is more than 10GW of surplus for many hours of a day. They do not need your help during these hours. This is the reason why utility companies store otherwise wasted energy in the form of pumped up water, high-speed flywheels, molten sulfur etc., even though entropy-wise they are net energy losers. They are better than total waste.

5) Speaking of the peak hours, the demand curve of a day is similar to one cycle of the sinusoidal graph. If we can cut off the peak portion of it and fill it in the valley (peak shaving) you can reduce the max capacity requirement of the grid greatly. As I mentioned elsewhere household UPS made out of the A123 batteries will make this a reality.

 

[Texas]

Texas, what part of my post is BS? (I think we exchanged our views on this subject in the old forum.)
First of all I am all for the household solar electricity generation. My main point is that with the high-capacity storage device such as the A123 batteries the rooftop solar panels will become more meaningful.

Let’s go point by point…
I hope you agree that:
1) If we can be independent of the grid, so much the better. (Texas, do you work for a utility company?) Americans, especially those who live in the state of Texas, value independence more than anything else. Being independent of the grid means we can be less affected by natural and manmade disasters.

2) Raw solar energy per square meter (approx. 11sf) is about 1kW, somewhere around 0.14kW of which is turned into electricity if the panel is looking squarely at the sun. If you put an array of 10’x20’ panel on your roof (not perpendicular to the sun in many cases) probably you can get up to 2kW of power during six or so daytime hours. So, conservatively speaking we can store some 8kWh of energy into your own storage device while we are at work. Efficiency of solar panels is getting better and better. Mitsubishi electric made an announcement earlier this year that they would start mass-producing panels of 18% efficiency. DuPont and U of D reported that they had reached more than 40% percent, which would free many of us from the shackle of the grid completely if the panel is combined with a high-capacity storage device.

3) AC power distribution system is a two-way street therefore; the Ferranti effect is a nuisance to the grid. Any glitch or spike at the downstream goes back upstream, amplified.

4) Other than the peak hours the grid has plenty of surplus. Take the Caiso, for example, there is more than 10GW of surplus for many hours of a day. They do not need your help during these hours. This is the reason why utility companies store otherwise wasted energy in the form of pumped up water, high-speed flywheels, molten sulfur etc., even though entropy-wise they are net energy losers. They are better than total waste.

5) Speaking of the peak hours, the demand curve of a day is similar to one cycle of the sinusoidal graph. If we can cut off the peak portion of it and fill it in the valley (peak shaving) you can reduce the max capacity requirement of the grid greatly. As I mentioned elsewhere household UPS made out of the A123 batteries will make this a reality.

1) No, I feel being connected is better. When you need some you buy. If you have some extra (what about when your batteries are all full or when there is many days of cloudy weather) you buy. Smart grid, V2G, energy as the new currency. Point: we disagree completely.

2) When looking at the panels I only care about the cost effectiveness of the solution. If 40% efficient panels cost 10X as much I would rather have 14% efficient panels that are made like newspapers. Again, connected to the grid is easier to balance. Point: we disagree completely.

3) That is a bunch of crap probably invented by people that don't want anything on their grids. It works fine and will get batter as the industry designs things better for connection to the grid. Point: we disagree completely.

4) My entire smart grid plan is to use the pumped storage hydro and other electrical storage systems to handle massive amounts of solar and wind resources from around the country. The only fossil fuels needed will be for extreme conditions for back up when not enough power is coming into the grid. You think of solar as a trickle charge. Point: We disagree completely.

5) No, we want to match production as closely to demand as possible. That is what we do today with our pumped storage hydro plants and natural gas power plants. This is exactly why pumped storage hydro and other electrical storage systems play a huge part of the solution. You are basically feeding the grid exactly what power is needed. When there is excess it’s used to raise the water levels or charge up the battery banks in our national transportation fleets as well as stationary battery banks. Correct, no system is 100 percent efficient. However, this is a completely renewable, sustainable system that will work for as long as the sun is shining. The energy cost will only come down as technology gets better, not be completely unknown because you are not sure what the cost of coal, uranium, NG, oil, etc. will be in the coming years. Reduction of risk has value. Believe it. Point: We disagree completely.


Thus, we are completely opposite in our thoughts about solar and the role it has to play in our energy future. It's OK, everyone has their own opinion. Ours are just dichotomous.

 

[BluesBrian]

A better way would be to install about 3KW or solar on the roof of your house. Then connect the system to your local electric utility grid. Sell back the power that you make in the middle of the day to the utility and use utility power at night to charge your Volt. This way you won't need a large set of batteries and the efficiency lost by charging one set of batteries (the Volt) with another set of batteries in your house. In effect you are using the electric grid as a battery.

This sort of system is called net metering. It's mandated in some States, optional in others The actual price paid back to you per kilowatt hour as well as the price you pay at night will depend on local laws and/or the policy of your local electric utility.

Agree! .. and this works if the average daily car usage is within the charge range of the battery.
I think that the electic utility company should be obligated to buy all of the power that you generate, and not just the portion that you use.
An alternative would be to setup a residential energy co-op, that would force the buy-back issue.

 

[Texas]

Agree! .. and this works if the average daily car usage is within the charge range of the battery.
I think that the electic utility company should be obligated to buy all of the power that you generate, and not just the portion that you use.
An alternative would be to setup a residential energy co-op, that would force the buy-back issue.

What are you talking about? I think you got things all backwards.

1) It works regardless. It's just a question of the system cost and if the utility is setup for net metering.
2) The utility company does not buy just the portion you use. That makes no sense at all. They purchase the access amount (if they allow net metering). Your panels generate power, your house is using power, the positive difference is purchased by the utility at an agreed upon rate. No need to setup residential co-ops.

 

[solarcar2]

Great Ideas Make Great Things Happen

Hi volton
I see a lot of good discussion you inspired. Like you, I would like to charge an electric car off grid if possible. Also, I have actually done the math.
I can't speak for all areas of the US but I live in the Northeast at 43 degrees lattitude. I would need to install a minimum 2000 watt solar array to charge a battery bank consisting of eight 6V 375AH batteries in order to charge the Volt.
This represents an investment of approximately $10,000. in PV panels and related equipment for a do-it- yourselfer to build a PV system capable of charging the car. If you paid an installer to put a system in for you, you could probably double that amount.
In my opinion, this is not a cost effective option to charge the car. Neither is a grid tied PV system, even with the incentives being offered in some states.
I think we both need to wait until the cost of PV systems becomes more reasonable, and it should in the next few years even though government is still wrangling with how they will get tax dollars from drivers no longer buying fossil fuels.
I intend to be patient on this one. Cheers! solarcar2

 

[gwmort]

I dug this thread up with the search tool, I don't know if something more recent may be more appropriate, but...

I have also been thinking about portable solar charging. I've read the threads with the numbers and agree it doesn't make much economic sense. For instance, the Plug-in Prius is supposed to have a solar roof for running cabin cooling system, it generates about 50W and is a $3000 option. If it could trickle charge for 8 hours at work and get full efficiency the full time it might give enough juice to go almost 2 miles. If you assume $4.00 gas and about 40 mpg that slight charging will save you 1/20 th of a gallon of gas a day, or about $4 every 20 days which means the ROI on the $3000 is around 41 years.

So lets leave practical economics out of it for now.

I want to know if it is possible to use a portable solar system like this one:

http://www.amazon.com/Brunton-Watt-Foldable-Solar-Array/dp/B000GEFFBO/ref=pd_sim_auto_2

To charge a portable power source with an inverter like this one:

http://www.amazon.com/Duracell-DPP-600HD-Powerpack-Starter-Emergency/dp/B000TKHMWK/ref=pd_sbs_sg_2

To eventually charge the Volt.

I figure if it is possible the charging would suck the portable power source dry in seconds. What I am wondering though is if that solar array can charge the power source everyday, and everyday it can put a few seconds of charging into the Volt, would it eventually charge up?

Again I recognize this is completely impractical, thinking more as a thought experiment in an end-of-the world, totally self sufficient, zombies over-ran the power plant kind of thing.

 

[stresstool]

I'd say no. The EVSE in slow mode draws 8amps @ 120v ~=1000watts. You'd need a pretty beefy powerpack to supply that. The one you list says 450watts continuous. Consider also pulling 1000 watts from a 12v battery means ~80amps, so you'd need some pretty beefy wires from the battery to the inverter if you didn't want to lose most of the energy in transit. A 28ah AGM battery is only 28ah if the draw is around 2amps (I think). At 80 amps, you are quite correct, the battery would be dead in a minute or so.

The 26 watt solar provides about ~2amps peak. So to get 28ah it would have to have a minimum of 14 hours of peak sunlight. But the battery won't charge in a linear fashion. It's pretty linear up to around 80% SOC, then it slows down and you might expect it to take just about the same amount of time for the last 20% as it took for the first 80. So I'd gues 14*.8 = 11.2 hours x 2 = ~23 hours of bright sunlight to replace the charge. Unless it's the middle of the summer probably around three days.

 

[gwmort]

I found a 62 watt version of the fold-able solar cells and read you can connect multiples together to increase the current.

I guess another way to look at it is I know we can trickle charge a battery to from the solar cells. What I want to know is if there is an off-the-shelf battery/inverter combo that would actually get some usable charge into a volt given the current state of the car (no direct dc input).

 

[gwmort]

While looking for off-the-shelf portable power supply equipment I stumbled into the battery back-ups for computers and office equipment. I really hadn't been thinking this way, but the ratings on some of these look pretty beefy in terms of being able to supply a significant amount of power. Most say they are tolerant of a wide range of input voltages and strictly regulate output to protect the electronic equipment tied to them. Check out these stats:

UPS System, Smart UPS(R) On-Line, Power Rating 1500 VA, Watts 1050, Voltage 120, Hz 47-63, Voltage Output 120, Backup Time 22/8 Min., Number of Outlets 6, Outlet Type 6 UPS/Surge, NEMA Receptacle 5-15R, Automatic Volts Regulation, Transfer Time 0ms, Height 3.35 In., Depth 22 In., Width 17 In., NEMA Plug Configuration 5-15P, Ports DB-9 RS-232, Smart-Slot, USB, Special Features On-Line Rack/Tower Convertible, Standards BSMI, CSA, FCC Part 15 Class B, UL 1778

Again, I am fully aware there is nothing practical or reasonable about this approach, I'm just looking at possible, post-apocalyptic, Kevin Costner delivering mail type scenarios.

 

[ctdeng0]

If you are serious about solar charging I would look at 24 vdc solar panels and 24 vdc inverters. You can then use 2 12 vdc AGM batteries in series which could easily supply the 40+ amps to run the inverter. You would likely have to delay the charging until you have replenished the battery capacity. Most inverter will automatically shut off when the battery gets low.

I measured 870 watts on the 110 volt charger set to reduced charge. A 24 vdc 1000 watt inverter will likely set you back $700.

 

[LGA]

The 220-volt Voltec charger takes 1300 watts or about 16 amps.