Solar Panels and PHEVs

I suspect that an infinite number of solar panels would not charge your electric car overnight.

---No sun!--- :lol:

 

<div class='quotetop'>QUOTE(mgipe @ Aug 31 2007, 01:16 PM) [snapback]505115[/snapback]</div>

The OP needs to check with their utility company.

Not all do net metering - whereby the car could be recharged at night with credits from daytime solar production.

The other thing to find out is if, at the end of the year, the utility will pay you for any extra solar power credits which you did not use. Most utilities DON'T . . . which is really unfortunate. They will gladly take your extra power without paying you for it . . .

. . therefor, in designing your system, if you go over 100% of your yearly need, you are spending money you will never see a return on. <_<

 

Boulder, this is a two part question

1. How much energy will the car use ? about 200 - 250 watt-hour per mile. Multiply this by miles driven per month ..

2. How much energy will a 1000 watt panel produce per month in your area ? That information should be forthcoming from your installer. Cross check their numbers with your local solar energy groups.

----
As an aside, a couple bits of advice

1. Heat your water with solar heating, not PV
2. First spend money decreasing your home energy energy use. Smart choices regarding lighting, insulation, conservation, shading and light, and AC can be quite a bit less expensive then PV. As an example, a clothesline instead of a dryer for my kid's incessant clothes washing will save over 100 kWh per month in drying 10 months of the year.

I'm guessing you will install a tie-in to grid with net metering ? It's the best way to go.

All the best !

 

We have netmetering (meter spins backwards if we generate more then use) and also use TOU (time of use) metering. The TOU really makes a big difference. Basically we have a peek time 12 - 7pm where electricity is at its most expensive. The other times it is cheap(er) Weekends are 24hr at the same low rate. So I recommend that you look into getting appliances with timers. We do our dishes at midnight, laundry starts at 6:00 am and we stop using the dryer before noon and resume after 7:00pm. I also put all our entertainment stuff on a powerstrip and turn that off when we go to bed. the standby power sucks up to 25% of running power on some electronics.

so with a bit of change in schedule you should be able to get away with 3KW system (provided you don't have more then 2200sq ft) else I would aim at a 5K system. With current rebates you can probably expect to get half of the cost back and then a approx $1800.00 tax benefit

 

Darreldd might be able to give you some ideas, as he does this with his EV. He hasn't been around for a while though. If you have an AC, rip it out and put in a swamp cooler. You'll save loads on electricity. In CO we get a $2.50/watt rebate from Xcel Energy and a $2.00/watt rebate from the state. There's also the $2000 fed tax credit. Shop around, there are many installers in our area. One of my friends is installing an 8.1 kW system and the cost to him is gonna be around $33K. A 2.5 kW system will cost you around $12K out of pocket. A prius sized car will go about 4 mi on a kWh so factor that in along with the size of the array and your monthly household consumption and you'll get an idea.

 

<div class='quotetop'>QUOTE(tripp @ Aug 31 2007, 03:30 PM) [snapback]505169[/snapback]</div>

True, but I found the swamp cooler to pretty darn ineffective if we got above 92-93 F. I'm currently planning a heat-pump geothermal system for next year. We get triple digits too often, and if I wanted to be that hot and humid, I'd live in Texas.

 

Apologies boulder if this stuff is obvious, but your response makes me think a primer may be useful:

1 kilowatt (kW) = 1000 watts. This is a power measure
1 kWh (kilowatt*hr) is an energy measure

power * time = energy.

You buy PV by the watt, but decide how to size your system by matching energy production to consumption.

 

Contact the National Renewable Energy Center in Colorado. They have "boiler plate" work books for estimating energy demand (based on latitude, elevation and heating-and cooling-degree days). Coupled with your life style, this will give a good estimate. As photovoltaic panels become more efficient, you may need plus or minus one more panel. A tracking PV system (follows the sun throughout the day) will increase output with fewer panels.

A better built house with super windows, SIP roof and lots of thermal mass will require less electricity. Use of Sunpipes and clerestory will increase natural lighting and decrease electricity demand. Efficiency is the key to making good decisions.

 

<div class='quotetop'>QUOTE(efusco @ Aug 31 2007, 01:02 PM) [snapback]505109[/snapback]</div>

You mean the battery that GM says doesn't exist yet, but they're "working real hard" to develop? I think anybody reading this and waiting for a Volt is going to be too old to drive before the Volt exists. Never underestimate the capacity of American business to deceive.

 

I had earlier posted that a Prius requires about 200 - 250 Wh per mile. Multiply by 4, and convert 1000 watts to 1 kW, and you get Tripp's 4 miles per kWh.

Note: NOT kilowatts. It is kilowatt*hr.

What you are calling 'electricity' is energy, measured in the US as kWh. You will get to know and love that unit of measure, as you size your system. Pull out a utility bill; it will show you how many kWh of electricity you used this past month. My utility lets me see a year of my use on it's web site.

A solar panel is spec'd to it's maximum power rating. Course, it's not always working at maximum efficiency. so the energy generated is a sum of how it did through all the seconds of the month. Not so good at night or on cloudy days, for e.g. Don't try to figure this out with math; just ask your installer how much energy a month each kW of PV on your house is going to generate. S(he) will also tell you how much each kW of PV costs installed, and how much roof area is required.

Check out nmsea.org for oodles of information. I'm sure CO has something similar -- I just do not know a web address.
A nice primer: http://nmsea.org/Education/Homeowners/Buyi...lar_Systems.pdf

 

<div class='quotetop'>QUOTE(Boulder Bum @ Sep 1 2007, 08:03 PM) [snapback]505596[/snapback]</div>

Hours times kilowatts equals kilowatt hours. Therefore with a one kilowatt panel it will take ten hours of full sun to charge the car. Now the efficiency of the panel comes into question. The panel must have a solar tracker in order to charge at anything near 100% of the rating. Any clouds or other obstructions will decrease the amount of power generated.

I hope this helps.

 

<div class='quotetop'>QUOTE(Boulder Bum @ Aug 31 2007, 07:11 PM) [snapback]505182[/snapback]</div>

OK, here goes. Three terms are useful to know and understand when dealing with electricity. Watts, amperes, and volts. A good analogy is to think of electricity as water traveling through a hose or pipe.

Watts is how much water passes through the hose (this is how the power company measures your usage).

Amperes is how big (as is diameter) the hose is (this is how much electricity at any given moment is passing through the wire with respect to voltage).

And volts is the pressure of the water in the hose (the more volts the smaller the wire gauge needed to carry any given load. For example, motors can be made smaller (cheaper) with the same power as a larger lower voltage motor. House wiring (as in Europe's 230 volts for residential use vs. our 110-120 volts) can be a smaller gauge. BUT, the greater the voltage the more dangerous the circuit with respect to accidental electrocutions. You can use equations to figure out other values such a kilowatt hours, wire sizes needed to carry a certain load safely and such but I will leave that for you to research ;-)!

So what you are primarily interested is how many kilowatt-hours a cell can generate during the day. If a cell can generate 100 watts in ten hours it will generate one kilowatt hour, or about 9 cents of electricity in my neck of the woods. That's the same as a 100 watt light bulb burning for 10 hours, or five 100 watt light bulbs burning for 2 hours, and so on.

That's IF the sun is at the angle needed during all that time to generate 100 watts. Keep in mind the angle of the sun will change with the seasons and of course during the course of the day. It may be cloudy (think Chicago or many northern areas during the long winter months) where power output will be low. While here in FL they may be effective more often than most areas we have to worry about hurricanes and tropical storms ripping the panels off their anchors. It has also been stated that some panels degrade significantly over time.

I admire people who put significantly amounts of PV panels on their houses and pay little or no electrical costs to the utilities. But the upfront costs are high and currently with today’s electrical costs it seems unlikely you will recover your investment from an ROI point of view.

Let's hope soon PV cells will be priced in the future to effectively compete with the utilities in the future.

Rick
#4 2006

 

<div class='quotetop'>QUOTE(Mad Hatter @ Aug 31 2007, 04:43 PM) [snapback]505173[/snapback]</div>

You must have higher humidity than us. We're comfortable above 100 F. The heat pump is a good idea though. How much would that cut down on your energy usage?

Wp (Watts peak) is usually measured at 25C (77 F). At higher temps the efficiency drops some. Most panels are rated to produce 80% of original after 25 years. This is a very common spec.

Rick, in CO we get pretty generous rebates from the State and the Utility. That, coupled with the fact that you can often deduct the interest from financing (plus the fact that rates creep up inexorably) and the ROI is pretty good.

To quote Ferris Bueller... "If you have the means, I highly recommend picking one up."

No one is using trackers anymore (except for CSP and utility scale PV installations) because they're not cost effective. They can require expensive maintenance. It's cheaper to just add more panels to get the output you want.

 

<div class='quotetop'>QUOTE(Mad Hatter @ Aug 31 2007, 03:43 PM) [snapback]505173[/snapback]</div>

Just like here in Sacramento, you too have the ideal climate there in Kelseyville (low humidity and a large differential between high and low temperatures) . . .
http://www.wrh.noaa.gov/forecast/MapClick....2&map.y=124

. . . for a Whole House Fan.

http://www.eere.energy.gov/buildings/info/...an.html#Cooling

WHY MAKE COLD AIR WHEN YOU HAVE IT PROVIDED FOR YOU, FREE OF CHARGE, AT NIGHT!
JUST SUCK IT INTO YOUR HOUSE!!!!!

We rarely have a need to turn on our air conditioner, because, on most nights, we can chill down the house with the whole house fan. In the morning we close-up the house and it stays comfortable until the next evening- at which time we can turn the whole house fan back on. The other benefit of the whole house fan design is the attic gets the heat blown out for no extra cost. We do not have, or need a separate, and less efficient, attic-only fan.

Our house was built in the 1920's and is not all that well insulated (I am working on it) and the house also still has the original, double hung, single pane, inefficient and drafty windows.

You can run a whole house fan all night for less than what it costs to run a central air conditioner for only one hour.

The best way to use a whole house fan is to chill down the interior with the coolest night air. And I do mean chill!
The walls, furnishings, cabinets - everything - is cool to the touch in the morning. The house is then closed-up during the day and has no problem staying comfortable.

The same concept works in the spring and fall to warm-up the interior during the warmth of the day.

The cost of our whole house fan has been paid back many fold since I installed it seven years ago. My summer electric bills are basically the same as my winter electric bills . . . and I have gas heat!

PG&E will also give you a $100 rebate!
http://pge.com/res/rebates/whole_house_fans/index.html