Who Should Invest in Grid Tied Solar (Economic Return on Investment)
• You use more than 15kwatthours per day and
• You can elect a time of use structure (yes CA)
• Your area has more than 3-4 noon suns without major shading,
• You can make a return on your investment within 10 years while helping the earth get less toxic.
Note: Ecologically, if you have the money and want to help the world use less coal and nuclear energy . . .It is reasonable to invest in solar no matter what your energy usage as long as your area is not heavily shaded and receives at least a couple of noon suns per day. The power utility will insure that someone uses the energy that you produce. So even if your usage is less, it is still a great ecological investment.
WHERE?
INSOLATION tables
http://www.bigfrogmountain.com/SunHoursPerDay.html
Photovoltaics due to light refraction can generate energy even with some fog.
San Francisco (at the airport) gets about 95% of San Diego solar energy.
Remember that insolation charts don't take into account local shading so if you live in a wooded area, your amount of solar energy available is significantly less.
FUN FACTS
3.5 kwh/year to charge an iphone 1 x to full each day
this represents 2 hour (charge)/eday @ 5 watts of power for 1 year
E = P x t
E = 5 watts x 2 hour/day x 365 day/year = 3.7 kwhour/year
Does this include everything --
Unfortunately, the amount of energy used to make the iphone valuable is monstrous. Running all the data centers uses enough electricity to run 200,000 homes. Thankfully, google has also invested money on the order of running 600,000 homes in renewable energy.
And I'm not even sure that the 30kwhour / day for residential home accounts for the water companies need to pump the water and it certainly doesn't account for the behind the scenes energy google and youtube use to make the content available.
20 loads of laundry (sun dry) uses less energy than a wash and a dry
How much Electricity do we consume?
This is a great site on electricity usage
Numbers for the Economy of Solar
Conservation and reducing your usage to less than 10kwatt-hours per day will save you more money than investing in solar. A solar system can't compete against 12 cents (national average) per kilowatt-hour. (The first 10kwatt hours are often cheaper than usage beyond that.)
Grid tie $ 0.50 - 1.50 for every watt hour of useable production per day
10 usable kwatt-hours = $10,000
Battery Based System 3.00 - 3.50
10 usable kwatt-hours = $30,000 (batteries cost a lot and decrease usability by about 20%)
Electricity Production & Retail Costs
Solar Energy roughly costs 15-17 cents to produce
Conventional utilities charge between .06 and .50 with a national average of 12 cents.
Factors in cost per kilowatt-hour
• Demand Side Management -- More expensive energy the more you use.
• Time of Use -- more expensive when everybody wants it (midday in summer when AC is blowing)
Demand Side Management illustrated:
In Baja, if you use less than 2kwatthours per day the government helps subsidize and you only pay about 5 cents per kilowatt hour.
In CA, if you use less than 10kwatthours per day, you are in a rate around 10 cents per kwatthour.
Sadly this makes investment in solar not as good as conservation but ideally both, especially since electricity costs likely will rise in the future as we reach peak oil and hopefully good policy around burning dirty fossil fuels.
Time of Use
Always elect Time of Use if you install a Solar System because you get the highest rate during summer days when you are producing the most. Conversely, set your electric dryer to dry your clothes in the middle of the night.
Grid Tie
40 states have mandatory net metering. Mexico mandates net metering as well.
California / U.S. subsidies.
30% of the system cost can then count toward your federal taxes
So that 10 useable kilowatt hours system can give you $3000 back in federal tax credit (not a deduction – you pay 3000 less in taxes)
Pay for a solar system RETURN on INVESTMENT -- in 7 – 15 years. and this isn't assuming drastically inflationary energy prices which is possible.