If you apply power to the Vin terminals while the Electron is in sleep modes you will get the 100ma charge limit.
If you use my PMIC code to bump charging current to 1amp then once the setup loop runs the charging can go up to 1 amp.
Now this higher charging current will hold as long as the power applied to Vin remains regardless of charging current, so you will still be able to charge at the higher currents even in deep sleep. This should be no problem during the daylight hours with a solar panel attached to Vin.
If you remove power to the Vin terminals during deep sleep then it will revert back to 100ma charging until the setup code runs again.