I'm considering having a solar panel electrical system installed.

[LD1]

It ALL boils down to COP. (cost of payback)

And that (I think this thread illustrated VERY well) is different for everyone.

And there are only 3 things that influence COP:

1. Your electric rates. Mine are 11 cents/kwh But other areas of this country are north of 30, so that right there "could" drop the COP by 3x's

2. Does your utility company offer net-metering. Mine does NOT. So when myself and the wife are at work, and the house is consuming VERY little juice, and its a nice july day that 20-30k system is giving electric away all day to the utility company for FREE. And then at night, when we get home and I take a shower and lay in bed and watch TV and the water heater kicks on, I have to BUY my electric even though I just gave them a TON of kwh's for free earlier that day Crock of S**T if ya know what I mean.

3. The last thing that effects COP is how much the system costs. Grants, credits, tax incentives, local programs, etc all lower the cost. As others have mentioned ~$3/watt if you install yourself is pretty accurate at the moment.

For me, based on my current 11 cent rate and no net metering and $3/watt set-up, my COP is north of 20 years. I am kinda the worst case scenerio.

For others with 30cent+ rates AND net metering, the COP could easially be UNDER 5 years.

Reducing electric use, and/or upgrading to higher efficency stuff does NOT reduce the COP. Because you would benefit from those changes regardless wether you have solar or not. For example, you install a $20k system and anticipate a 10 year payback. And after the first year, you have a major lifestyle change or whatever and are only using 1/2 the electricity and selling the rest back, THAT does NOT cut the COP in half. Because you would have to re-figure how much it would have costed you without solar. And the pre-solar cost would also be cut in half.

You guys get the idea.

 

[KTurner]

Reducing electric use, and/or upgrading to higher efficency stuff does NOT reduce the COP

Decreasing your usage could allow you to purchase smaller (less expensive) equipment, such as the inverter. This may or may not matter, depending on your electric company and the net metering agreement. In a situation where they do not pay you for your surplus, it doesn't make sense to have a system any bigger than what your house uses during the day as that is unused capacity which just increases your system cost and makes it take longer to pay for the system.

Some companies change the rate when you hit a certain number of KWH in a billing period. My electricity company changes the rates at 800KWH. During June-September, KWH #801 costs about 20% more than KWH #799. I could buy just enough of a solar system to keep my bill below 800kwh and the per-kwh payoff would be quicker than if I did a system large enough to supply my entire usage. I'd be targeting the more expensive KWH's. Of course, my electric costs (per KWH) change throughout the year, so that makes the equation a bit more complicated.

You could always just chalk it up to a hobby instead of an investment. Get some new toys and play. There's much less research/homework involved in a hobby versus an investment.

Keith

 

[RobertN]

I figured out how to get back online for our solar. Here is graph of past year, and July 2011. At the bottom of both graphs is an overall lifetime; ours goes back to September 2010. Scale is not good, but can see trend.

One thing I did not see mentioned here....

We reroofed just before the panel went on... We were due anyway. But, as much as we like our results, I would hate to reroof and have to pull these panels up...

 

[RobertN]

Today, so far. Overcast with sprinkles here and there.

I figured out how to get back online for our solar. Here is graph of past year, and July 2011.

 

[LD1]

Some companies change the rate when you hit a certain number of KWH in a billing period. My electricity company changes the rates at 800KWH. During June-September, KWH #801 costs about 20% more than KWH #799. Keith

Mine is actually just the opposite.

The more you use, the less the overall bill is per kwh.

As I mentioned before, I track mine with a spreadsheet. I use about 800kwh LESS in the summer. Due to having a heatpump for primary heat, winter months it runs more than in the summer.

And my winter bills curently are averaging ~10.5cents/kwh for ~2400-2600kwh and they are ~11.5 cents in the summer for 1500-1700 kwh bills

 

[SPYDERLK]

Actually, the accepted figure is 1000w/m^2 at sea level, perpendicular to the sun, at high sun, AT THE EQUATOR.

Actually, the accepted figure is 1120W/M^2; a total of all direct and scattered light on a surface normal to the sun rays on parts of the earth presenting them at a low zenith angle. You will get a great deal of incomplete info unless you include the key "word" 1120 in a search.
larry