Demeter,
A good deal of what you got here already is accurate, but not really what you asked for.....
Quote:
Originally Posted by SV Demeter
I know there are a lot of variables but is there a general rule of thumb that would allow me to estimate how many amps hours of output I could expect to see under optimal conditions per watt of solar array?
Something like "you should be able to get on a good day in the tropics "X" amp hours out of a 100 watt panel"?
Im looking at assembling a 4 panel array of 135 watt panels and using an outback flexmax 60 chrage controller and Im trying to get a ballpark estimate on how many amp hours on a good day I might get.
Thanks,
|
So, here, in a nutshell is the "general rule of thumb, for determining how many amp-hours per day, you'd get out of a solar array in the 'tropics'...."
No formulas, no "variables" to fudge, etc....
[Please note: I do love Beth Leonard, and do respect her well-earned reputation.....but most of her and Evans' voyaging is/has been in higher latitudes, and I'm not sure if she's had much experience with modern charge controllers (either PWM or MPPT).....]
1) The commonly accepted "Rule-of-Thumb" is:
In the tropics (assuming you don't have much, or any, panel shading)..... Take the total number of watts of your solar array and divide by 3 (or multiply by 0.33)....and that number equals the approx. number of Amp-Hours per Day (A/H-day) that you can expect from you array.....
(The above "rule-of-thumb" does not apply to high latitude sailing.....)
2) In addition to keeping the panels from being shaded, if you mount the panels in the clear, allowing for plenty of airflow under and around the panles (and/or spalsh some sea
water on them occassionaly), keeping them cool.....And, if you use a good quality MPPT controller (Blue Sky, Outback, etc...), You can increase that number of A/H's per day, that you can expect from the array....
This is a controversial point, since it does rely on the subjective variables of "shading", panel temps, battery state-of-charge, etc.....
BUT, it is clear that if you have good sun angles (summertime or in the tropics), and have plenty of airflow under and around the panels, using a good MPPT controller, you CAN get significantly more than the old "rule-of-thumb"......
Although, I'm hesitant to post the
number here, since there are many that discount it, and for certain you should NOT plan on this output.....but, if you do it right, you can get as much as 40% - 45% of your panel's
wattage number out in
amp/hours-day......
Do NOT discount the affect of panel temps on their output.....
If you can keep them cool, they'll output above their "specs"/"ratings", with high sun angles,,,such as in the summertime
Bahamas, etc...
3) FYI, in addition to my
current 520-watt solar array on-board, I've been using / insatlling solar on board boats on/off for over 15 years.....and have been using / installing solar on-shore in far
remote loacels since the early 1980's....almost 30 years now.....and I've taught seminars on alt. energy, solar power, batteries, etc.....I've seen a lot of new stuff (PWM controllers were a great boost....and then came MPPT controllers, etc...as well as new panel designs, etc....)
4) Have alook at an article I wrote (w/ lots of photos) of my
current 520-watt array on-board....
Solar Panels
5) Demter, as long as you can rig/insatll your panels in the clear, free of shading and with plenty of airflow.....sailing in "the tropics" (within the tropics of Cancer and Capricorn) you should see 200+ A/H-day average from your 540 watt array year long......and probably closer to 225 A/H-per day, average year long....(assuming you can keep the panels cool...)
Since shading really cuts down your daily average output, as does having hot panels, etc.....use the "rule-of-thumb" above as your guide, and try to mount them in the clear....
That's the best
advice I can give...
I hope this helps...
John
s/v Annie Laurie