Solar Pannels

4.6 meters will recieve about 1200 watts/meter 5.4kW, apply efficency of 25%, 1.3 kW, then apply time of about 5 hours/day, net 6.5 Kw-hr per day or $1/day savings.

Most panels I see are 130-190 watts at 17 volts (then regulated to 12-14 vdc for battery charging), and these are 2x4' or 8 sq ft. That's 150 watts per panel, or a total of 900 watts. Count on 5 sunny hours/day (depends on region) and you get 4.5kwh per day. Other variables like aiming of the panels and weather of course can make a difference.

I agree, go look at the sun intensity graphs, but remember they are just averages.

In Texas there is a wide difference between the Houston, Dallas, El Paso, Perryton, Austin, Brownsville, and Lubbock areas. If you go look at some of the states web sites, they will even explain the differences in the 5 major geographic areas (that is the number I remember anyway), and the solar intensity will vary.

Also, on a 'flat surface' is different if it is on a flat surface tilted toward the sun at roughly the same degree as the latitude, or flat on a flat roof, or on a pole with a 'sun tracker'.

I hope some of this helps!

Our rule-of-thumb is 100 square feet of solar modules for every kilowatt generated (i.e, five kilowatts needs about 500 s.f.) Preferred term is modules, but everyone uses panels anyway--depends, too, on output--count on actual output to run 96% to 98% of RATED output (i.e. 175 watts RATED output = 168 watts ACTUAL output), plus further losses due to 100+ degree temperatures (i.e. It's BLOODY HOT in Texas!)

NREL provides an easy to use calculator. Go to www.nrel.gov/rredc/pvwatts/version1.html

It uses local weather data and standard efficiency numbers.

Version 1 gives you a choice of fixed data locations. Version 2 allows you to enter zip code or other location information. Start with Ver 1 - it's much easier to use.

In Texas how much energy could you produce from about 50sq.ft. of solar pannels on a flat surface?

Probably not enough to justify the cost. However; you would experience a warm and fuzzy feeling knowing that you are reducing your "carbon footprint" and helping to put off the inevitable heat death of the planet.

In Houston, about 4.5KW/m**2/day or about 9KW/day (a bit less) for 50sq ft.

Think of a square meter as being about 30 square feet.

In Lubbock and El Paso it is almost 5KW/sq meter/day or 10% more than Houston.

Brownsville is about 4.6, San Antonio 4.5, DFW area 4.9 (I am surprised), Lufkin 4.6, Peryton 4.7, Marfa 5.1, Amarillo 5, Austin 4.5, Crawford (near Waco) 4.6

You didn't say WHERE in Texas you are interested.

Yea, they are 'back of the envelope' measurements, but its as close as most 'engineering estimates'. Figure about 8 to 12 KWH/day for 50 sq ft. And that is annual average. As always, YMMV.

'Think of a square meter as being about 30 square feet.'

I take it that these are the new small sized feet and not the normal 12" feet! Do you mean 3 ft² or 9 sq feet?

I like that, the newer small size feet.

Yes, I messed up. I was thinking cubic (then it would be 27 cubic, not square feet).

Also a square meter is really larger than a square yard, it is roughly 10.76 square feet per squere meter, so 'roughly', using the 'new smaller size feet' you can use 11 square feet to be a square meter, for 'engineering estimates' anyway :)

In fact, Google is great at things like this... type in "1 sq m in sq ft" and you get:

1 (sq meter) = 10.7639104 sq feet

Works with all kinds of units--type just as you'd say it, e.g. "50 gal in cu ft" or "25000 sq ft in acres" -- very handy!

- B