Channel power and occupied bandwidth are among the most common tests, along with adjacent channel leakage ratio (ACLR), operating band unwanted emissions (OBUE), spurious emissions, Tx on/off power, error vector magnitude (EVM), frequency error, and time alignment error.
A digital multimeter checks electrical connections, measuring voltage, current, and resistance. For example, it helps identify issues like power losses caused by faulty wiring.
A photovoltaic system with storage consists of solar panels, an inverter (which converts energy from direct current to alternating current), a management system, and, indeed, batteries.