A few years ago we got into solar to power ham radio equipment. 18 Volt, 100 watt panels (name plate maximum 5A at 18 volts) were available, for $100, and we could power modest projects like remote packet radio nodes. These needed a deep cycle battery and semi smart charge controller, that would protect the battery from over charge and deep discharge. We have had good luck with two solar AX.25 packet nodes up on our regional backbone, where a large 100A sealed lead acid battery, 100W panel and Icom HT (low standby power draw) provide packet rain or shine.
A few of our surplus construction light tower trailers came with the diesel engines removed. These had a series of 100W panels installed and some batteries. One of our friends, Eric, bought a “Progress Solar” brand solar light tower trailer. These have around ten 100W panels, a series of large batteries (6-8) and LED lights. He says he gets “1000 watts” of solar production on these on a good day.
Our radio trailer, the Dawg House, has one 100W panel, a Group 31 marine deep cycle battery and tiny $12 charge controller. That can produce best case around 30 amps at 12 volts net a day. The key to solar/battery is to have more power produced and stored than actually used by a lot. The radio gear can draw power 24 hours a day, the panels only produce say five hours a day. Clouds, rain and snow (not cold) impact production.
We just bought a Starlink Gen 3 “dishy” – it draws 60 watts (measured, average) at 115V AC. We bought a nice semi intelligent 500 watt pure sine wave 12VDC >115V AC inverter. This pushed our power needs well past what we can make.
In home grid tied solar systems (I have one, 6KW, 14 panels) the big 70×41 inch 360 watt 40 volt panels are used. The panels are wired in series mostly, higher voltage reduces wire sizes neeed. For quite a while the panels and required charge controllers were a bit pricey. Recently, a 40 volt in, 12/24/48 volt out 1000 watt PWM solar controller was spotted on Amazon (JJM Brand) for like $30 and found its way to my shopping cart.
The solar panels come with three kinds of wiring. The cheap ones have USB jacks or those little coaxial wall wart 2.1 mm connectors. Those are for charging cell phones and are not waterproof. The next size up have those two pin flat automotive/Motorola radio DC plugs. They look like the ones on trailers and have like #16 wire. They are OK. The larger panels have the “RC4” connectors and like #10 wire. This is what you want.
The price of solar panels has come way down. I found three surplus 360 watt Panasonic 40 V panels from a solar installer. They were new at $140 each.
I got them home. They are big and delicate- class fronts and not the strongest frames. They are designed to sit in a sturdy roof or ground mount frame. I found some $29 solar panel aluminum tilt mount adjustable brackets on Amazon. The solar panels are absolutely huge. One person can barely lift them. I made a wooden travel crate out of 1/4 inch plywood (nearly a full sheet) and pine 1x3s for each of mine.
The name plate power output is fascinating – 11 Amps at 38 volts. The charge controller sends this out at the auto sensed battery type and voltage. I tried it a bit in the driveway. I got 3.5A at 38 volts per panel so far. I ended up buying another Group 31 marine deep cycle battery. The idea is to try and store the peak noon sun for use at night. The panels in the crates are big and heavy. I did buy more Amazon Basics canvas sand bags to hold them down. The plan was to be able to make and store enough solar power for the Starlink to be run 24 hours a day at a disaster/recovery scene.
I get a lot of coaching to buy the newer Lithium batteries. Our deployments so far have been mid winter. So four degrees F. Lithium batteries charge poorly below 32F. I did upgrade the trailer charge controller to the bigger one. The big solar panels crates may travel in the truck.
Ham Radio Tower Trailers 