The way to squeeze the most watt-hours out of panels and into batteries
is with MPPT regulators. "Maximum power point" regulators that adjust
rapidly to the real time insolation. A series regulator is throwing
away W-H.
See http://en.wikipedia.org/wiki/Maximum_power_point_tracking
some interesting references particularly the thesis that describes what
he built with the PIC based controller.
OTOH, a 15 to 20 watt panel connected to a 100 A-H battery really
doesn't need a regulator. Just check the water every few months. I had
such a setup run a community water system radio control of the well
pumps and the battery would last about 5 years 24 x 365, with about a
50ma load. Worked in San Jose, CA. Might not work in Seattle. :-(
Grant KZ1W
Redmond, WA
On 9/25/2014 4:33 PM, Don Kirk wrote:
Hi Bruce,
Their are numerous methods used for sizing solar panel systems, and using
one of the common methods provides the following for your application as
follows :
Using a battery charging efficiency factor of 120%, and Portland Maine as
the location (winter average = 3.56 sun hours/day) . And designing for a
reserve capacity of 3 days (3 days of no sun), with a minimum battery
capacity of 50%.
If designing for continuous power applied to the preamp (24 hours per day)
: Required battery capacity = 18.7 Ah, Solar panel = 1.05 amps (almost a 20
watt panel).
If designing for 15 hours of continuous service (using a day/night
controller) : Required battery capacity = 11.7 Ah, Solar Panel = 0.66 amps
(approximately a 10 watt panel).
The above method is somewhat simplistic (does not take into account how
cold temperature impacts the capacity of the battery, etc.), nevertheless
it provides some reasonable numbers to put things into perspective.
I'm sure you will think the panel and battery are large, but that's what it
takes to handle continuous service during the winter when day light is
minimum.
Note : solar panels really operate like a constant current source versus a
constant voltage source, therefore a typical solar panel for 12 volt
battery charging will have an open circuit voltage of around 21 volts but
this is under a zero output current condition. The maximum output current
of a solar panel is when you have it's output short circuited but it's
current at max power is not much less than its short circuit current. An
easy way to characterize what kind of panel you have is to measure under
bright sunlight the short circuit current, and the open circuit voltage of
the panel.
Don (wd8dsb)
On Thu, Sep 25, 2014 at 2:55 PM, <k1fz@myfairpoint.net> wrote:
Hi Don,
Pre-amp requires 12-18 volts at 130ma. (low band DXing- nightime use)
This solar charger puts out 20 volts that could be reduced to 15 volts
with a three legged regulator. I was hoping to find a pre-assembled
charger & battery, but may have to build one.
http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html
73
Bruce-K1FZ
What is the operating current and voltage of the preamp you plan to
use? Since it sounds like the preamp will be powered on all the time this
information will be key in the selection of the battery capacity and solar
panel rating.
Don (wd8dsb)
On Thu, Sep 25, 2014 at 1:30 PM, wrote:
Anyone using, or know of a source, for a compact battery with solar
cell charger, to power a remote antenna pre-amp ?
73 Bruce-K1FZ
www.qsl.net/k1fz/pennantnotes.html
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|