Photovoltaic installations require a minimum and simple maintenance limited to the following operations:

• Panels: they require very little or no maintenance due to their specific configuration: there are no mobile parts and the cells and their inner connections are encapsulated inside several coats of protective material.
  
  It is advisable to carry out a general inspection once or twice a year: make sure that the connections between panels and regulator are well fastened and corrosion free.
  In most cases, the rain effect eliminates the need of cleaning the panels. In case it is necessary, a non-abrasive detergent and water is just enough.
  
  
• Regulator: the simplicity of the regulating equipment reduces substantially its maintenance and makes breakdowns very rare.
  
  The operations that can be carried out are the following: check the state of the regulator and its working condition visually; check the connections and the wiring of the equipment; check the instant values of the voltmeter and ammeter. They supply an index of the behaviour of the installation.
  
  
• Accumulator: it is the element that requires most attention; its service life depends in great measure on its correct use and maintenance. The usual operations that must be carried out are:
  
  • Check the electrolyte level (every 6 months approximately): it must be within the margin of the "Maximum" and "Minimum" marks. If these marks are not present, the correct level of the electrolyte is 20 mm over the spacer protector. If a lower level is observed in any of the elements, it must be refilled with distilled or demineralised water. It must never be refilled with sulphuric acid. – When carrying out the above operation, the state of the battery terminals must also be checked; the possible sulphate deposits must be cleaned and all the connections covered with petroleum jelly.
    
    
  • Measurement of the electrolyte intensity (if a densimeter is available): with the accumulator totally loaded , it must be from 1,240 +/- 0,01 to 20 Celsius degrees. The densities must be similar in all the vessels. Important differences in an element may mean a possible breakdown.
    
    
• Inverter: currently, most inverters do not require any specific maintenance.