Sol 3 uses QMK firmware. Documentation on installation, keymaps and compiling can be found here.
To install the default keymap:
Install QMK Toolbox
Flash the left half
QMK Toolbox: Choose the firmware .bin with
Reset the board by pressing the reset switch on the PCB.
Flash: Press the flash button in QMK Toolbox.
Flash the right half
Repeat the above with the same .bin file.
Plug the leftmost port into your PC, and the two middle ports into each other.
After the initial setup, you can update your keymap using QMK Toolbox, and you only need to flash the primary half.
For custom keymaps, do the following (To be changed when Sol3 enters QMK master)
Install QMK MSYS and open, run the following:
git clone -b development https://github.com/rgbkb/qmk_firmware
qmk setup - press Y when asked to install submodules
qmk compile -kb rgbkb/sol3 -km default
To update your repo, run the following
git remote add upstream -t development https://github.com/rgbkb/qmk_firmware
git pull upstream development
If dependencies have changed, you may need to re-run
If QMK Toolbox doesn't work, try these steps