We installed 2403 Watts of British Petroleum solar cells, and a SunnyBoy 2500 W inverter on our Pasadena, California home about a year ago.

We use "net metering" so have no batteries (city power is reliable, its just 70% coal!)

Officially operational April 7, we are on track to cover 90% of our annual electric for a three bedroom home, family of five people, five computers, three TVs and an old microwave.

Needless to say, we love it!

Had we not replaced our old gravity feed gas heater this year with forced air, and added air conditioning (as we had a new baby in June), we would have easily reached 100%.

As it happens, too, last spring was the rainiest on record for Southern California, with resulting cloud cover.

We get the most electrical generation on cold clear days in winter (we have a sharp angle on our roof, better for winter)and the cold air increases solar panel efficiency over the rated amount. A cold, short winter day produces about 16.5 kWh generation for us, while a long hot summer one averages more like 12 kWh.

After rebates, our professionally done install costs us $40 per month amortized over the warranty period of the cells, and is free after that. (We paid with a small equity loan.) BUT since the appraised value of our house increased just about that much -- tax free in California -- the cells and electricity are essentially free.

Things we'd do different:

1. We get a bigger array. Although we got the max array for the rebate available, we would now find a way to max production on the space we had. Although we can add cells, it would be a headache. And we would rather over-produce and have more electric than we needed than be at 90%. We also may be look at an electric car for city use, and would have loved to have it be solar.

2. We would have found the extra money for a slightly more aesthetic installation. I have been eyeing with some jealousy the cells with angle-cut panels and finished edges. Not a big deal, but would have been nice.

In addition to the solar, we subscribe to the City of Pasadena "Green Power" which delivers 100% of our non-solar from wind and geothermal.

So, as electric rates went up 15% in Southern California last year, we were very pleased that our costs are not capped. Sometimes as the world wobbles over fossil fuels and the potential for shortages loom, we wonder if we shouldn't have put in a battery backup . . . but since we have never had the power go out now that we live here in town, we haven't felt the strong need.

There is so much more to say; the construction experience was like any such project, with miscues and hassles of various sorts. But the end result was more than well worth it!

We installed a grid-tied 2.5kW system about two years ago. Simply put, we love it. Our electricity costs in 2004 amounted to about $37 (down from ~$900). We had a baby in December 2004, so in 2005 our electricity costs jumped up, what with the extra heat and diaper-washing and so on, to about $100. My "solar blog" contains a running commentary on the installation, maintenance, and various ins and outs; see http://debris.com/journal/solar

If you're considering a PV install, see especially the "solar math" post for an overview of how the numbers work: net metering, time-of-use, rebates, breakeven, etc. The simplified equation is: pay for ~10 years of electricity up front, but get free power for 20-30 years.

I have done the math for the requirments to go solar in panhandle Florida. I looked at my power bill and saw that I consume on average 60Kwh a day. Now am I wrong to think that if I wanted 100% to be provided by solar that I would have to install an array of 60 100W panels? If so, that is crazy as it would take my lifetime before I reaped any financial benefits. I would love to be "green", but with the cost per ~100W panel being around $800 each....well, you do the math.

So if anyone could help me if im wrong in my assumptions and explain where I am incorrect.

Side note, i'm a native of Newport..ironic that I found this site..small world.

The basic rule of thumb is to expect 5 hours of full sun a day. So 60 kWh / 5 hr = 12 kW. 12 kW / 0.1 kW per panel = 120 panels.

Maybe you could reduce your consumption a little? :)

60 kWh a day? Even without trying to conserve, we use *at* most* 12 kWh a day. If you don't have a super large house, or other energy sucker like electric water heater or stove or dryer or all three, I would take a *serious* look at consumption. And remember: Any process that creates heat from electricity is probably the most inefficient mode available for the job, from dryers to stove and back.

"I looked at my power bill and saw that I consume on average 60Kwh a day."

I agree with the previous poster in that you should always first look to lowering your consumption through efficiency before sizing your system. 60 kWh/day is an extraordinary amount for a single household.

Just looking at climate data for Tallahassee in 2005, it seems you have a temp range there from 20-100 F, with about 1500 heating degree days and 2700 cooling degree days, with a yearly mean temp of 68 F. So obviously you have more cooling than heating load.

I also wonder if you have a pool, and how it and your house's hot water are heated.

Thermal solar has much quicker payback periods than photovoltaics, so whatever water heating needs you have could be done with solar. And since you have relatively mild winters, solar forced air or a heat exchange system with thermal solar could substitute for any central heating in your house.

I also assume your home isn't that well-insulated, so your cooling load is going to be much higher than it would be if you had better insulation.

Just guessing as to your specifics, but I definitely think you have a lot of room to lower your electricity consumption before sizing it for photovoltaics.

Here's statewide data, for your reference:
http://www.eere.energy.gov/states/state_specific_statistics.cfm/state=FL#consumption

Looks as if per capita household electricity consumption is about 17 kWh/day and that Floridians use very little natural gas in their homes.

I agree about conservation for Rich W. I have records back to 97 for our electric usage and we currently average 8 kwh/day..and we have all the modern conveniences of life in a 2000 sf house (but no air conditioning).

My neighbor mentioned his electric bill went down by $50 a month when they retired their 42 year old fridge...it just sucked those electrons.

We have a 12 kw array with a Sunny Boy Invertor that just finished its 3 year of performing great for us. We are net metered, no batteries...part of PGE grid which is required for the solar rebate. AFter the rebate and tax credit, the system cost us 8000 installed. We pay about $15 a month for electricity. We did it at a time when solar was cheaper..I understand the same array, due to increases in demand, would be almost 3 times as much now. Anyway, the ONLY drawback I see, is having to clean the array during dry weather because as dust settles, it decreases efficiency. BUt that is my husbands job so I shoud not complain.

Roger, Gone Green,

Where did you learn that using electricity for heat is inefficient? Electric heating is 100% efficient. It can be (and often is) more expensive than gas heat, but from an efficiency standpoint, electric heaters/stoves/etc. are extremely efficient.

@The Anonymous Poste

The thing is most electricty is produced from fossil fuels. Mostly only half of the energy content of the fuel is converted into electricity. So looking at the whole chain it is more efficient to generate hear by burning the fuels at the place where the heat is needed.

"but from an efficiency standpoint, electric heaters/stoves/etc. are extremely efficient."

If you divide the thermal output by the thermal content of the original fuel source, it's very inefficient. On averagem about 2/3 of the energy content of the primary fuel is lost by the time it gets to the outlet. So it's about 30% efficient.

Comparatively, a high-efficiency forced air system using natural gas is around 90% efficient.

Not if you have a roof covered in solar cells :-)

Does that 90% take into account NG pipeline distribution energy and losses?

Man, I really need an energy consultant or something for my 1959 cinder block house. We currently use about 28kW/day and I have no idea what it all comes from.

Last month was our first with a new electric water heater (VS the ancient propane model) and it only increased 3.8kW/day. We didn't use the AC at all during either month. Just ceiling fans.

I've calculated out that our lights equate to about 5kW/day (gets lower every month as I slowly replace burned out bulbs with CFs), my computers are about 7.75/day (nothing I can really do about this), and my refrigerator is about 2kW/day (or at least it is supposed to be according to it's EPA rating of 750kW/year--I tested it once for a 24 hour period and that is about right).

That only leaves our oven/stove (which we use almost every night--no idea how much they use), the washer/dryer, and our TV which isn't on very much at all and has a standby draw of less than a watt.

The vacuum only uses about 1kW a month (Dyson DC-14 used once a week).

I really want to cut our consumption down, but I can't justify a new fridge when we'll *never* make up the cost (only about half as efficient as our current model) and I can't see how much a new electric stove or oven will be more efficient. New Washer/Dryer, on the other hand, just might be worth it if only to get stackability.

My best guess is that the stove/oven are our big energy hogs next to the AC in the summer (which will be a lot lower this year thanks to my extensive air sealing efforts!)

-Riskable
http://riskable.com
"I have a license to kill -9"

Just an FYI: The reason why natural gas isn't used much in Florida is because it isn't available. There may be natural gas wells around (no idea), but it wasn't until recently that they figured out a way to safely submerge natural gas lines in the ground (extremely high water table).

Natural gas is making it's way around, but progress has been very slow.

-Riskable
http://www.riskable.com
"I have a license to kill -9"

Its much more efficient to heat water and air using solar heat panels/tubes than to collect it via PV panels and then convert it to electric heat.

Everyone subscribe to http://www.homepower.com - you can get a 1-year electronic subscription for $15. You can even order all the back issues going back 15+ years for a reasonable price. Best solar mag out there.

"Not if you have a roof covered in solar cells :-)"

Still have conversion losses, plus the fact that you could substitute thermal solar for PVs and get much higher about per unit of area. But I realize you said that somewhat tongue-in-cheek.

"Does that 90% take into account NG pipeline distribution energy and losses?"

You think that 2/3 of natural gas never gets to the end-use point? That's how much it would have to be to be as inefficient as using electricity to heat. I assume it's pretty small, considering they don't break out system losses when reporting end-use consumption data, unlike electricity.

If you also want to get technical, heating isn't just about blasting BTUs, it's about distribution of that heat. It's why radiant floor heat can be extra efficient, because we perceive temperature often from the coldest spot on our body, which is often the feet.

And if you wanted to be even more technical, you'd need to look at the energy consumed from point of mining, but then you get into the difference between marginal energy use and sunk energy consumption in the form of extraction and delivery infrastructure.

Regardless, it's pretty clear that combusting straight to heat is going to be more efficient than combusting to heat, converting to electricity, sending it 1,000 miles, then converting to heat.

Of course, electric heat can be useful for supplemental and/or zone heating, if you want to take it further, since combusting fossils indoors without venting isn't the world's best idea -- though portable kerosene heaters are not uncommon in places like Japan.

"Not if you have a roof covered in solar cells :-)"

Still have conversion losses, plus the fact that you could substitute thermal solar for PVs and get much higher about per unit of area. But I realize you said that somewhat tongue-in-cheek.

"Does that 90% take into account NG pipeline distribution energy and losses?"

You think that 2/3 of natural gas never gets to the end-use point? That's how much it would have to be to be as inefficient as using electricity to heat. I assume it's pretty small, considering they don't break out system losses when reporting end-use consumption data, unlike electricity.

If you also want to get technical, heating isn't just about blasting BTUs, it's about distribution of that heat. It's why radiant floor heat can be extra efficient, because we perceive temperature often from the coldest spot on our body, which is often the feet.

And if you wanted to be even more technical, you'd need to look at the energy consumed from point of mining, but then you get into the difference between marginal energy use and sunk energy consumption in the form of extraction and delivery infrastructure.

Regardless, it's pretty clear that combusting straight to heat is going to be more efficient than combusting to heat, converting to electricity, sending it 1,000 miles, then converting to heat.

Of course, electric heat can be useful for supplemental and/or zone heating, if you want to take it further, since combusting fossils indoors without venting isn't the world's best idea -- though portable kerosene heaters are not uncommon in places like Japan.

We recently lived in an off-grid home powered completely by solar panels and backup generator. Somewhat off topic, but important if you go solar, is selecting efficient appliances (such as clothes washer): do your own homework rather than gravitating to the models touted as efficient - Energy Star qualifying covers a pretty wide range and we found that many of the models that were being marketed as low-energy-usage used much more than other models made by the same companies. We were on an older, very basic system, yet we ended up loving it and as soon as possible want to invest in a system for the home we moved to.

Here's a trick to get the most energy out of your panels. Most people (who don't have solar panels that track the sun) align their panels to get most of the sunlight most of the time. Usually that means direct light at high noon, and less than that at all other times. It makes common sense to do so, but unfortunately, this is not the most use-effective way of getting solar power.

What actually works better from the point of view of usage is to take a month and chart your electricity usage, and graph your average usage vs. the time of day. Then, align your panels to receive direct light during the times you need it the most, rather than to an overall average that is not indicative of your actual electricity usage patterns.

Personally, I would recommend tracking the sun. But where this is not practical or cost effective, the above approach is the next best thing.

There is one other trick that you may want to know to get more electricity out of your panels: the sun's angular hight in the sky varies by 46 degrees between the summer and winter solstices, because the earth's tilt is about 23 degrees. That results in about an a peak of about an 8% loss for the weeks around each solstice. I did some calculations to determine what you can do to get most of the light most of the time, and my resutls are as follows: Presuming that your panels are tilted to the an angle corresponding to your lattitude so that it receives direct sunlight during the equinoxes, tilt your panels back 16.2° during the spring equinox, and tilt them 16.2° forward (from neutral, not from the tilted back position) during the fall equinox. This will give you more direct sunlight for most of the time; anything more would require more work on your part.

national Solar home tour,

Check on www.ases.org to find if there are any houses near you. It's held the first weekend in october. I've gone to them the last 3 times and its great to see new things people are doing.

If you get your house set up with PVs before the tour, you can show off your house being in the tour!!

Berkana, your suggestions and numbers are off, unfortunately. The sun is highest in the sky during the summer, so your panels should point highest then (your latitude + 15 degrees if I remember right). Fall and spring equinoxes end up being the same angle - not completely different angles as you suggested. Winter will be your lowest angle.

We installed a grid tied net metered PV system in Coventry Rhode Island at The Apeiron Institute for Environmental living. www.Apeiron.org
I was the project manager for the multifaceted project. It freaked out the meter reader for the electric company to see the meter running backwards. The institute keeps records and can answer questions you may have. They are open to the public by appointment.
Eliot Raymond

I just started looking at solar power. I currently use around 125 kilowatts per day. This is down from 190 kilowatts when I first moved into this house 7 months ago. I have had an energy audit and have corrected everything that was suggested to become more energy efficent. The electric company says that is should take around 130 kilowatts to run my house daily so they are no longer helpful. I have around 3700 square feet house with a very large pool and seperate hot tub. I see posting for 60 kilowatts and people saying thats high. I live in Austin, TX and it is around 100 everyday. I keep air on 82 day and night. I am agreeing with some that say it does not look cost effective. Please any advise is greatly appericated.

I just installed my system, and I live in South Florida.
My costs were about 26000 for the parts and 7000 for the labor. So far a whole month has gone by and we've sold back to FPL over 100kWh.
www.bocasolarhome.com

Before I started I decreased my consumption first, that is the key.

My state refund was $17000 and my federal was $2000.

This is the single most useful page I've ever found on Solar.

It is great to get real information about actual usage, and to read that people are delighted with their systems, warts and all.

Thanks a million,

Cormac.

The cheapest and easiest way to be more green with electricity - use less.

Back on the efficiency question: electric baseboard at 30%, gas furnace at 90% (will degrade over time), try a heat pump, which will deliver something over 300% above 45F, and will also cool you when it's hot. Add solar to the equation, and you're using zero fossil fuels, adding power to the grid when it's most needed (to air-condition homes and schools and office buildings), and you're using the most efficient source of heat (except for ground-source, which not everyone can afford either in drilling/digging costs or acreage...) HEAT PUMPS - get the scoop before you buy a gas furnace. If you live someplace cold, you can still do a heat pump: Hallowell heat pumps don't need backup heat down to MINUS 20F. See http://www.gotohallowell.com/i

I have just started looking at my energy consumption. We live in central Florida and our 2,200 square foot, 5-person household uses around 70 KWH daily in the winter months. In the summer, with air conditioning, the number is closer to 120. Both central air units are new (not by choice - they were old when we moved in and soon died). I am looking at adding more isulation in the attic for that problem.

I'm also replacing incandescent lamps with flourescents and trying to cook more on the propane grill outside during the summer.

One thing I've noticed that really sets the meter spinning is water pumps. I have set the pool pump (no heater) to run only 2 hours a day so that should help.

The well pump runs when it needs to recharge the pressure in the air-bladder system, so there'e not much I can do about that, thouth the pump looks to be about 20 years old. Are pumps any more efficient than they were 20 years ago? Is there some other way to slow-charge the water pressure and keep it up over longer periods, I mean besides building a water tower?

We recently purchased solar rings for our pool as a maintenance and assist to heat pump. It occurs to me that a solar ring could be constructed with parabolic mirrors in the center, with a conducting rod in the water, increasing the amount of solar heat transmitted to the water. Is this a feasible model? 3/16/08