I'm sorry that I discovered this thread late in the discussion but
can you tell me what the "MPPT" you mention is?

As I read your post this MPPT somehow increases the amount of power
developed by the Solar Panels. Is this true?

I ask this as my experience is that my experience has always been that
solar panels developed (on a sunny day) approximately rated output
watts/battery voltage when monitored using an amp gauge.

If you have a system whereby the system outputs a higher voltage then
the above mentioned formula allows then obviously the charging current
will be higher as the internal resistance of the batteries is pretty
much a constant for any given voltage and I would like that very much.

Again I apologize for coming into this discussion late but if you know
a way that allows me to develop a higher voltage then the usually
calculated watts/resistance I certainly will incorporate it in my
system.

Thank you in advance for your information.



On Sat, 09 Apr 2005 00:11:53 GMT, Walt wrote:

My 0.0002, could be wrong..

I have a 160 watt panel and when the sun is shining and the panel is aimed
right, and Im using an MPPT controller, Im getting reasonably close to 160 watts
out of it - like maybe 150..

What Ive seen are calcutions based on the rated power of the PV panel and
assuing that you get 5 hours of sunlight per day. On good sunny days, this
possibly underestimates the power. On cloudy days, you might get a lot less.
Using current to compare things is ok but it doesnt take into account voltage.
What really is important is power.

Here are some rough calcs..

At 450 watts PV power and assuming using MPPT (which works and improves
efficiency for either 12 or 24 volt systems), the output current at full power
is (power = voltage * current)

15 amps for 24 volts system (15 = 450/30 volts - assumes MPPT allows panel to
operate at 30 volts rather than battery voltage)
30 amps for 12 volts system (30 = 450/15 volts - assumes MPPT allows panel to
operate at 15 volts)


Cheers,

Anon
(Bangkok, Thailand)