Off-grid systems

Off-grid PV systems are classified under three main categories, DC-coupled storage (Battery at the DC-side), AC-coupled storage (Battery at the AC-side) and Hybrid (Automatic transfer to utility when battery is discharged).

An analysis of the number of DC coupled storage, AC coupled storage and Hybrid Off-grid systems installed by each company was made. The conclusions for each type of Off-grid PV systems are:

DC coupled PV systems: Six (6) companies have installed between 0 – 10 of this type of Off-grid system, one (1) between 10 – 20 and one (1) more than 30. Only one company has not yet installed DC coupled storage PV system since its incorporation.

AC coupled PV systems:Six (6) companies have installed between 0 – 10 of this type of Off-grid PV system and one (1) between 10 – 20. Two (2) companies have not yet installed AC coupled storage PV system since their incorporation.

Hybrid PV systems: Five (5) companies have installed between 0 – 10 of this type of Off-grid PV system and one (1) between 10 – 20. Three (3) companies have not yet installed AC coupled storage PV system since their incorporation.

As summary, the percentage shares of total DC-coupled, AC-coupled and Hybrid Off-grid PV systems account for 44%, 30% and 26% respectively. This is represented as shown in Fig.16. and Fig.9. below.

Fig.1: Types of off-grid PV systems installed

Different types of batteries are used in Off-grid PV systems. Local PV companies use more than one type of battery in their PV projects. An analysis of the types of batteries used by each company was made and the conclusions are: Seven (7) companies incorporate these batteries in their Off-grid PV systems, out of which five (5) companies also use Lithium ion together with Lead acid batteries.

One (1) company uses only Lithium ion batteries and one (1) company uses only Lead crystal and Lead carbon batteries. Lead Acid batteries shares the largest share with 77.8%, Lithium-ion with 66.7% and Lead Crystal & Lead Carbon with 11.1%. Nickel Cadmium batteries have not been used by any local PV companies yet.

Fig.2: Percentage share of batteries used by local companies

An analysis of the per kW cost (Rs) of the different types of Off-grid PV systems installed by each company was made. The conclusions for each type of PV systems are:

DC coupled storage: Two (2) companies have a per kW cost (Rs) of between MUR 50k – 75k for this type of Off-grid PV system, four (4) between MUR 75k – 125k and two (2) greater than MUR 125k. Only one company have not installed DC coupled storage Off-grid PV systems.

AC coupled storage: One (1) company has a per kW cost (Rs) of between MUR 50k – 75k for this type of Off-grid PV system, five (5) between MUR 75k – 125k and three (3) greater than MUR 125k.

Hybrid: Five (5) companies have a per kW cost (Rs) of between MUR 75k – 125k and one (1) greater than MUR 125k. Three (3) companies have no Off-grid Hybrid PV system.

Fig.3: Range of per kW cost (Rs) of the types of off-grid PV systems by local companies

As summary, the percentage shares of the per kW cost (Rs) of the total DC-coupled, AC-coupled and Hybrid Off-grid PV systems account for 33%, 40% and 27% respectively. This is represented as shown in Fig 4. below.

Fig.4: Per kW cost (Rs) of the types of off-grid PV systems

The cost breakdown of Off-grid PV systems composes of mainly six components/items namely Panels, Mounting structure, Power electronics equipment (Inverter, Controller etc.), Battery, Cables and protection and Design and project development. An analysis of the percentage share of components used in Off-grid PV systems by each company was made. The conclusions for each type of component are:

Panels: One (1) company has a percentage share of between 5-10% in the cost breakdown of Off-grid PV systems, two (2) between 10-15%, two (2) between 15-20%, three (3) between 20-25% and one (1) between 40-45%.

Mounting structure: One (1) company has a percentage share of between 0-5% in the cost breakdown of Off-grid PV systems, two (2) between 5-10%, two (2) between 10-15% and four (4) between 15-20%.

Power electronics equipment: One (1) company has a percentage share of between 5-10% in the cost breakdown of Off-grid PV systems, three (3) between 15-20%, two (2) between 20-25%, one (1) between 25-30%, one (1) between 30-35% and one (1) between 35-40%.

Battery: One (1) company has a percentage share of between 15-20% in the cost breakdown of Off-grid PV systems, two (2) between 25-30%, two (2) between 30-35%, one (1) between 35-40% and three (3) between 40-45%.

Cables and protection: One (1) company has a percentage share of between 5-10% in the cost breakdown of Off-grid PV systems, two (2) between 10-15%, two (2) between 15-20%, three (3) between 20-25% and one (1) between 40-45%.

Design and project development: One (1) company has a percentage share of between 0-5% in the cost breakdown of Off-grid PV systems, two (2) between 5-10%, five (5) between 10-15% and one (1) between 20-25%.

As summary, Fig 6. below represents the percentage share of each of the six mentioned components/items in the cost breakdown of Off-grid PV systems.

Fig.5: Percentage share of components in the cost breakdown of off-grid PV systems