Designing Solar Power Systems
This page is for FM translators (those FM transmitters for out in the sticks where city transmitters can't reach), but the details apply whatever your needs: determine how much you're going to draw 24 hours a day, figure out how much sunshine you get in a day (usually about five hours), then put 24 hours of your needs in a battery every day whether it's sunny or not.

That means you need a lot of solar power going into your batteries, and you need a lot of reserve in your batteries. Going totally solar is extremely expensive. This will help you determine if it's worth it for your application.

Philip, who came up with only 5 hours of sunshine per day? That seems extremely low to me.

That's probably an average. SOCAL will be an exception.

But an average of what? Where in the U.S. do you not get more than 5 hours of sunlight per day? Obviously rain/cloudy days aren't as bright but the sunlight is still there.

I grew up in the Midwest, lived in Colorado one summer and the rest of my life has been spent here in SoCal but even in mid winter in St. Louis we got over 5 hours of daylight.

There are also some pretty cool tracking devices that follow the sun as it moves across the sky which greatly increases the amount of useable solar power.

At any rate, solar is only going to get more economical, more feasible and more efficient as time and technology marches along.

Warning, IMNAE, so hopefully nomad or some other expert can check my numbers.

Its a matter of angles. Solar Panels produce 100% power when the sun in pointing directly at them. Once the angle becomes too oblique, the output drops fast.
So that rules out much of the morning and the evening.

Then, unless you are on the equator, you have to take your latitude and weather into account.

I am not against Solar, think it is a great tech. Bang for the buck is still low, but improving.

If your goal is conservation, reduce usage with better appliances, better light bulbs, and better habits BEFORE you look at solar. You get more bang for your buck, and when you DO go solar, you need to spend less on panels because you reduced your requirements.

Most Solar Panels run~$5.00/Watt.
Since grid power in the Midwest is $70.00/1,000,000 Watts
(Megawatt) you will need to use that panel a LOOONNNGG time to break even on a cost level...

Solar calculations also need to take into account the operational requirements throughout the year. Higher latitudes complicate the design to point that solar power becomes useless for many months during the winter. The cost of the installation is prohibitively expensive when looked at in the short term or even the medium term and even the long term (although the long term for grid electricity supply needs careful analysis as well as it might not always be available)

Solar Calculation for domestic Freezer application

From this previous calculation a 240W peak power solar PV with MPP regulator, high efficiency inverter and a 200AHr Battery installation at my location will produce over a year about 170-200KwHrs or typically a cost saving over using grid tied electricity of about £29-34 or $43-51. The installation cost would be around $2500 so would take around 50-60 years to pay for itself using current grid tied pricing. Solar PV could not hope to be cost competitive with burning fossil (previous stored Solar energy) and nuclear fuels on a large scale as the energy has already been accumulated. Grid Electrical energy is just a means of releasing previously stored solar energy rather than a means of collecting solar radiant energy, storing the energy then transmitting that energy to the customers load. Grid tied electrical energy companies who provide this electrical energy have for the most part have no means to provide long term energy once the previous naturally accumulated solar energy store has run out. They are also doing a good job at wrecking the environment at the same time trying to get to these ever diminishing energy resources. Drill baby drill has its down sides.

http://news.bbc.co.uk/1/hi/world/americas/8651624.stm

It is probably better to use naturally available hi energy efficiency solar energy accumulators at high latitudes during the winter months. They are inexpensive but just need a greater installation area. They also make great air conditioners during the summer months and even can provide humans with nutritional benefits and construction materials.

That's answered in the article:
"Since according to NOAA the sun averages 5.5 hours of 1000 W/m insolation at our proposed site above Vail ... " with more detail at
http://www.rbr.com/radio/ENGINEERING/95/13603.html

Solar power follows a bell curve of efficiency through the daylight hours. Based on the rated output of the panel, the average yield of watts generated over a period would allow only so many net hours a day total, not that the sun only shines for 5 hours, but that the energy generated equals a fixed number of watts per day. A 500 watt panel could be generating 50 watts between 7:00 am and 8:00 am, which is (roughly) equivalent to 10 minutes at the rated output.

Energy could be viewed as the accumulation of effort, and watts (power) being the rate of accumulation. You can say 500 watts for 5 hours, or 210 watts for 12 hours (or whatever elapsed time is from dusk to dawn), or anything in between, including a varying rate over time (the bell curve) but the net will still must work out to 2500 watt hours generated, or accumulated.

Rule of thumb is that in good conditions you can estimate solar panel power output as the rated output for four hours each clear day. Figure six hours a day if the panels are adjusted to track the sun.

Practical usable power from battery banks is typically a third of their rated charged capacity in amp/hours. A bit more if you use batteries with friendlier charging/discharge curves, a MPPT charging system, use twelve volt output directly or a high efficiency inverter. But seldom do you get more than half without shortening the life of the battery bank.

That isn't the final word, and such rough estimates won't replace a detailed engineering study, but it is remarkable how many times such a quick and dirty estimate is within a few percentage points of some very expensive professional analysis.

Yeah, I'm still waiting for my Oil Burner to "Pay for Itself" - same goes for my washing machine and water well. I did the math, and I must have made a mistake, because it says that those things are a cost, not an investment.

Now, if you're expecting your home-based power generation system to have a LOWER OPERATING COST than your grid-fed system, well, no, it's not reasonable to ever expect a decentralized system to operate at a lower cost than a large-scale production facility.

If that were the case, it would somehow and some way eventually be cheaper for you to make your own automobiles, to grow your own food, to make your own lumber and to make your own medications.

It's not. I grow my own food - to an extent. But I could never grow enough corn or wheat on my own. I can't smelt metal. I can't make plywood.

Photovoltaic systems are still appealing - but not so much from an individuals economic perspective.