Need Help with Electrical Revenue Calculation Spreadsheet

Hi Spacecannon -

The second link took me to SoCalEd's web page with links to the calculators, but clicking on their link caused my machine to hang. I could get to the Revenue Calculators via another path, and that did open the calculator for me.

It appears very straightforward to me. You fill in your planned generation capacity, your planned type of generation technology, and the expected power to be generated each hour of a typical year for your site and the calculator will figure out your revenue based on SCE's current tarrifs over the next 20 years. They do the de-rating due to age across the 20 years for you, I think. Hour 1 is midnight to 1 am, and so forth ...

Do you have the daily sunlight intensity values for your site? I believe there are public domain databases from the National Weather Service for their weather stations that can be used to estimate this. Good luck.

Anna

Anna

The form asks for the number of megawatts (or killowats, this matches the "overall profile" at the top) expected to be generated during each hour of the day. You calculte that number by knowing how many hours of sunlight there are each day in the year (from the ephermeris or Almanac), and at what average angle the sun is during the daylight hours, compared to your collector(s) angle, minus a de-rating factor to account for the average percent of cloud cover at your site.

Sunlight intensity and hence energy output is also a factor of the site's lattitude; the people who are building the photovoltaics should be able to calculate that part for you, at least as an overall average.

The average cloud cover on a given day of the year may already be calculated and available on the web. If not, you can get 3-15 years back of weather data and average. I'm pretty sure the makers of solar panels have some reasonable ways of calculating the energy ouput based on sunlight at a given lattitude and collector angle. Then you subtract from that for the clouds and convert to killowats or megawatts. It is rather tedious to do by hand, but pretty striaghtforward with a spreadsheet.

If you need a lot more detailed explanation than this, you might condsider hiring an engineer to help. Or a programmer who deals with this kind of topic and some of the relevant data bases a lot. (I have someone in mind, but he's not on CR4.) Though there are many more people claiming "renewable energy" experience than who really have any, these days.

Good luck.

Anna

Basically- you need to do some homework.

For Step 3, you will enter the 100 kW value in the capacity section. Then, enter unity (1.000) in the degradation column for each of the 12 months. For the rest of the time, you will have to get input from the PV supplier- If non is available, I suggest using the formula "A1 * 0.995" for each of the next 12 months, then copy the second year and keep inserting the block for each year after that. The 3rd column is programmed to self- calculate.

Then, the real work begins. For Step 4, you will have to go to a solar insolation chart that can give you daily sun-rise and sun-set times (to the nearest hour) for each day of the month- this should be available from NOAA or DOE.

I assume that the 100 kW PV is based on full solar contact at some peak hour, and that your panels are NOT tracking (solar following). That means that the output will vary each hour of sunlight based on solar angle vs your collector angle. Early in tne morning, the solar angle will provide MAYBE 10% of peak power (you can use solar altitude and position to calculate the angle of incidence and using trig, you can get a reasonable %-age of power vs. peak (use the sine of the angle compounded for both vertical and horizontal angel- example: if the sum is 30 degrees from direct in both the vertical and horizontal planes, the actual power would be SIN 30 X SIN 30 times peak power, or 0.5 X 0.5 X 100 kW, or 25 kW for that hour). Obviously, if your PV is a dual tracking unit, always use 100% and if it is just a horizontal tracking unit, use only one angle of incidence.

After you enter the likely output for each hour of sunshine for each day of the month and repeat for each month. When you have an entire year completed, copy it and paste it for each of the remaining years.

That is a lot of work, so keep your records and calculations on file for the next time. but it should get you where you want to go.

Good luck.