Galactic cosmic rays, as well as particles accelerated to high energies either at the solar surface or in the interplanetary medium, are subject to a wide variety of phenomena that can modify their energy distribution, intensity and composition over different time-scales. These effects are greater in the low-energy portion of the spectrum, and it is crucial to have instruments that are able to monitor energy intervals as low as possible and for a prolonged period of time. After the seminal results of successful space-borne missions, past (PAMELA) and present (AMS-02), the China Seismo-Electromagnetic Satellite (CSES-01) mission - in particular the High-Energy Particle Detector (HEPD-01) - aims to continue such studies, well into the 25th solar cycle and beyond. HEPD-01, launched in February 2018, is a light and compact payload suitable for measuring electrons (3-100 MeV), protons (30-250 MeV), and light nuclei (up to a few hundreds of MeV) with a high energy resolution and a wide angular acceptance. The very good capabilities in particle detection and identification, together with the Sun-synchronous orbit, make this instrument very well suited for low-energy studies; moreover, being HEPD-01 just the first of a network of similar detectors that will be lunched in the forthcoming years, the evolution of particles inside the Sun-Earth environment is going to be fully investigated. The latest results on the long-term solar modulation of protons and helium nuclei and on impulsive phenomena like Solar Energetic Particle (SEP) events and Forbush decreases, are presented.