back to getting started with solar

1 solar panels:




There's a huge variety of panels available for purchase and there's no way I can begin to cover them, so I
will just make a few recommendations. Fraudulent power ratings are extremely common, so base your power
expectations on the panel size if the wattage rating looks too good to be true. Also bear in mind that the
"honest" ratings are in fixed lab conditions, and you won't actually GET that any more than you will get the
listed MPG on that new car. Iowa sun in the summer will deliver about 75% of the honest rating in full sun.

When choosing a panel, carefully consider how portable it is. The big glass and PVC panels at Harbor Freight
look sturdy, and they are, but that makes them big, inflexible, awkward to transport, and heavy. None of that
is fun to deal with on Field Day. I personally prefer the 100w flexible panels. They're very basic, but do
a good job and are very portable for the amount of power they provide. (which is up to 75 watts) You can also
use one of the "solar kit" folding systems, which are usually either a large clamshell or a wallet that
unfolds several smaller sheets of panels. The wallets sometimes come with a build-in controller, but that is
ONLY for 5 volt usb power. Most of them also have a "raw power out" port, and you NEED THAT, don't consider
a wallet without a raw panel output - you will be connecting that to your solar controller. The USB port can
be used to either charge a cell phone or tablet directly, or be used to charge up a battery bank, although the
bank is more useful on longer events like a week in the woods camping. The bigger clamshells are usually
rated 100-200 watts, and the smaller wallets will rate around 18 to 45 watts. Due to their low production,
Most wallets are of no value to a Field Day station beyond keeping your cell phone charged.

Do the math. If your radio is going to have a 30% duty cycle at 20 amps and run for 6 hours, that's about
500 watt hours. If your 100w panels produce an average of 50 watts over 6 hours, that will provide 300 watt
hours of energy back to your battery. A typical car battery is 600wh, a typical deep cycle marine is 1,000wh.
Don't forget to add in the power consumed by your controlling laptop if running digital, or your logging
laptop if away from line power.

Unfortunately there are a lot of uncertain variables here, and nothing is ideal, so you'll probably get better
information from the operators as to how long things run on a battery. This year our digital station wiped
out a marine deep cycle battery in about 4 hours. That would suggest he needed 250w (average) of solar to
maintain his battery. This is only accurate if you need to keep your battery fully charged while the sun is
shining, like during a 24 hour event. If you're going to wrap up that evening, just try to offset the battery
drain so you can keep operating till close - it's fine if your battery is flat at tear-down time, so maybe
100w average would be all you actually need.

And since it's difficult to predict how much use any station is going to get on a given event, it's beneficial
to hook as many power systems as possible together into a shared grid, to distribute the load and charge. My
personal theory is this: "The more solar you have, the less you have to think about things, so just get as much
solar as you can, and hook as much as possible to a single power grid."


Dokio 100w flexible panel ($88 each or 4 for $300 at Ali Express)

Dokio 110w foldable kit with controller ($135 at Amazon)

Dokio 220w foldable kit with controller ($230 at Amazon)



last updated 11/30/2023 at 20:12:36