Photovoltaic system: electrical equipments selection
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Grid connected PV system <= 10kW (Residential)
One single phase inverter
- Typically, a 5kW grid-connected single-phase inverter. with UOC MAX ≤ 600V.
- One or two strings – Isctc < 25A, IAC < 32A.
- In this design there is no string protection.
- A PV main switch is necessary. When the inverter is indoors, an additional remote controlled switch at the DC cable entry point is recommended for emergencies services.
| Needs | String junction box | PV array main switch | Inverter | AC box (400V) |
|---|---|---|---|---|
| Switchgears and control (Q) | ||||
| - Isolation | • | • (d) | (a) | • (d) |
| - Switching (Making & breaking rated current | • DC21B | • (d) DC21B | (a) | • (d) |
| - Control | • (b) | • (d) | (e) | • (d) |
| - Over-current protection | (c) | • (f) | ||
| - Protection against Insulation fault | (h) | (h) RCD type B or A SI | ||
| Surge protection (SPD) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor Double insulation | Indoor Double insulation | Standard AC requirement + grid code requirement | |
| Metering | Inverter relevant parameters | Energy | ||
(a) PV array main switch could be included in the inverter. This solution makes inverter service or replacement more difficult.
(b) Remote switching for emergency services located as closely as possible to the PV modules or to the point of entry of DC cables in the building.
(c) No protection is required when the number of string does not exceed 2.
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection B curve recommended.
(g) This SPD could be unnecessary if there is another SPD in the AC installation at a distance of less than 10 metres.
(h) If the inverter provides no galvanic separation a RCD protection is necessary on AC side. IEC 60364-712 specifies RCD type B. Some local regulations require RCD type A SI
(b) Remote switching for emergency services located as closely as possible to the PV modules or to the point of entry of DC cables in the building.
(c) No protection is required when the number of string does not exceed 2.
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection B curve recommended.
(g) This SPD could be unnecessary if there is another SPD in the AC installation at a distance of less than 10 metres.
(h) If the inverter provides no galvanic separation a RCD protection is necessary on AC side. IEC 60364-712 specifies RCD type B. Some local regulations require RCD type A SI
Fig. P22 : Grid connected <= 10kW
10 to 100kW grid connected PV system (Small building)
One three phase multi input inverter without array box
- Typically, 10kW to 36kW grid-connected inverters, UOC MAX probably higher than 600V (i.e. 800V or 1000V), Isctc < 125A, Iac < 63A.
- In this range of power, inverters usually have between 2 and 4 maximum power point tracking (MPPT) inputs, so the number of strings in the same DC sub-network is equal to one or two.
- There is no need for string protection.
- A PV main switch for each MPPT input is necessary.
- When an inverter is indoors, additional remote-controlled switches at DC cable entry point are recommended for emergencies services.
| Needs | String junction box | PV array main switch | Inverter | AC box (400V) |
|---|---|---|---|---|
| Switchgears and control (Q) | ||||
| - Isolation | • | • (d) | (a) | • (d) |
| - Switching (Making & breaking rated current | • DC21B | • (d) DC21B | (a) | • (d) |
| - Control | • (b) | • (d) | (e) | • (d) |
| - Over-current protection | (c) | • (f) | ||
| - Protection against Insulation fault | (h) | (h) RCD type B or A SI | ||
| Surge protection (SPD) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor IP5x Double insulation | Indoor IP5x Double insulation | Standard AC requirement + grid code requirement | |
| Metering | Energy | |||
(a) PV array main switch could be included in the inverter. This solution makes inverter service or replacement difficult.
(b) Remote switching for emergency services located as closely as possible to the PV modules or to the point of entry of DC cables in the building.
(c) No protection is required when the number of string does not exceed 2.
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection (B curve recommended).
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h)
(b) Remote switching for emergency services located as closely as possible to the PV modules or to the point of entry of DC cables in the building.
(c) No protection is required when the number of string does not exceed 2.
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection (B curve recommended).
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h)
- If the inverter provides no galvanic separation a RCD protection is necessary on AC side. IEC 60364-712 specifies RCD type B. Some local regulations require RCD type A SI
- If the inverter provides at least simple separation
- Without functional earthing: insulation monitoring is necessary, it's usually done by the inverter in this range of power.
- With functional earthing: the earthing shall be done with a DC MCB breaker (C60PV 4P series 2 – 10A) or a fuse.
Fig. P23 : 10-100kW single multi MPPT inverter
One three phases inverter with One Array box
- Typically, 30kW to 60kW grid-connected inverters. UOC max is generally higher than 600V (up to 1000V), Isctc does not exceed 200A, Iac does not exceed 100A.
- This design has more than 2 strings.
- Reverse current protection is therefore necessary.
- A main PV switch is required. When an inverter is inside, additional remote-controlled switch at DC cable entry point is recommended for emergencies.
| Needs | String / Array junction box | PV array main switch | Inverter | AC box (400V) |
|---|---|---|---|---|
| Switchgears and control (Q) | ||||
| - Isolation | • | • (d) | (a) | • (d) |
| - Switching (Making & breaking rated current | • DC21B | • (d) DC21B | (a) | • (d) |
| - Control | • (b) | • (d) | (e) | • (d) |
| - Over-current protection | • | (c) | • (f) | |
| - Protection against Insulation fault | (h) | (h) RCD type B or A SI | ||
| Surge protection (SPD) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor IP5x Double insulation | Indoor IP5x Double insulation | Standard AC requirement + grid code requirement | |
| Metering | P, Q, PF, Energy | |||
(a) PV array main switch could be included in the inverter. This solution makes inverter service or replacement difficult.
(b) Remote switching for emergency services located as closely as possible to the PV modules or to the point of entry of DC cables in the building. The main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing for that purpose.
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection (B curve recommended).
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h)
(b) Remote switching for emergency services located as closely as possible to the PV modules or to the point of entry of DC cables in the building. The main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing for that purpose.
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection (B curve recommended).
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h)
- If the inverter provides no galvanic separation a RCD protection is necessary on AC side. IEC 60364-712 specifies RCD type B. Some local regulations require RCD type A SI.
- If the inverter provides at least simple separation
- Without functional earthing: insulation monitoring is necessary
- With functional earthing: the earthing shall be done with a DC MCB breaker (C60PV 4P series 2 – 10A) or a fuse.
Fig. P24 : 10-100kW single MPPT inverter
Multi single phase inverters design
- Typically, 6x5 to 20x5kW grid-connected inverters.
- The design used for residential building can be duplicated as often as necessary.
- In that case, the DC system is very simple and the AC system is very similar to usual AC systems.
| Needs | PV array main switch | Inverter | AC box (400V) | |
|---|---|---|---|---|
| Switchgears and control (Q) | See 5kW design | (h) | • (d) | |
| Surge protection (SPD) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor IP5x Double insulation | Standard AC requirement + grid code requirement | ||
| Metering | Energy | P,Q, PF, Energy, unbalance |
(h) If the inverter provides no galvanic separation a RCD protection is necessary on AC side. IEC 60364-712 specifies RCD type B. Some local regulations require RCD type A SI
Fig. P25 : 10-100kW multi single MPPT inverter
Fig. P25 : 10-100kW multi single MPPT inverter
Three phases inverter with two Array boxes (Na <=2)
Typically, 60kW to 100kW grid-connected inverters with 2 arrays. Array cable protection is not necessary for 2 or 3 arrays. The Isctc array ≤ 200A, Isctc ≤ δ400A, and Imax AC ≤ 200A. A PV main switch is required close to the inverter. Remotely operated switches in array boxes allow disconnects to be located close to the PV modules in the event of emergencies.
| Needs | String / Array junction box | PV array main switch | Inverter | AC box (400V) |
|---|---|---|---|---|
| Switchgears and control (Q) | ||||
| - Isolation | • | • (d) | (a) | • (d) |
| - Switching (Making & breaking rated current | • DC21B | • (d) DC21B | (a) | • (d) |
| - Control | • (b) | • (d) | (e) | • (d) |
| - Over-current protection | • | (c) | • (f) | |
| - Protection against Insulation fault | (h) | (h) RCD type B or A SI | ||
| Surge protection (SPD) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor IP5x Double insulation | Indoor IP5x Double insulation | Standard AC requirement + grid code requirement | |
| Metering | P, Q, PF, Energy | |||
(a) PV array main switch could be included in the inverter. This solution makes inverter service or replacement difficult.
(b) If switching for emergency services is required, the main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing.
(c) No protection is required when the number of arrays <= 3 (No cable sizing benefit)
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection.
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h)
(b) If switching for emergency services is required, the main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing.
(c) No protection is required when the number of arrays <= 3 (No cable sizing benefit)
(d) Service and emergency switching
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection.
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h)
- If the inverter provides no galvanic separation a RCD protection is necessary on AC side. IEC 60364-712 specifies RCD type B. Some local regulations require RCD type A SI
- If the inverter provides at least simple separation
- Without functional earthing: insulation monitoring is necessary
- With functional earthing: the earthing shall be done with a DC MCB breaker (C60PV 4P series 2 – 10A) or a fuse.
Fig. P26 : 10-100kW single MPPT inverter with 2 arrays
150kW to 500kW Grid connected PV system (Large building and farm)
Three phases inverter with more than two Array boxes
- Typically, 150kW to 500kW single inverter.
- This design is very similar to the previous one except that it has more arrays, which requires array cable protection.
- Istc <= 400A, IAC <= 600A.
| Needs | String | Array junction box | Generator junction box | Inverter | AC box 400V or other voltage (Transfoless inverter) |
|---|---|---|---|---|---|
| Switchgears and control (Q) | |||||
| - Isolation | • | • | • | (a) | • (d) |
| - Switching (Making & breaking rated current | • DC22A | • DC22A | • (a) | • (d) | |
| - Control | • (b) | • (a) | • (d) | ||
| - Over-current protection | • | • (c) | • (f) | ||
| - Protection against Insulation fault | • (h) | • (h) | |||
| Surge protection (SPD) | (g) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor IP5x Double insulation | Indoor Double insulation | Standard AC requirement + grid code requirement | ||
| Metering | P, Q, PF, Energy, Alarm, THD, individual harmonics | ||||
(a) PV array main switch could be included in the inverter. This solution makes inverter service or replacement more difficult.
(b) If switching for emergency services is required, the main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing.
(c) Array cable protection is recommended to prevent cable overszing. To ensure fast trip of protections 6 to 8 arrays are recommended.
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection.
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h) Galvanic insulation is provided by LV/MV transformer,
(b) If switching for emergency services is required, the main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing.
(c) Array cable protection is recommended to prevent cable overszing. To ensure fast trip of protections 6 to 8 arrays are recommended.
(e) Inverter shall include a protection for anti-islanding (in accordance with VDE 0126 for example)
(f) Overload and short-circuit protection.
(g) If there is no SPD in the inverter or if the distance between DC box and inverter exceeds 10m a SPD is necessary in this box.
(h) Galvanic insulation is provided by LV/MV transformer,
- PV system without functional earthing: insulation monitoring is necessary: IMD - IM20 and accessory IMD-IM20-1700
- PV system with functional earthing: the earthing shall be done with a DC MCB breaker (C60PV 4P series 2 – 10A) or a fuse.
Fig. P27 : 150-500kW single MPPT inverter with N arrays > 2
Multi single phase inverters design
Typically 10x20 to 20x30kW grid connected inverters
Uoc max ≤ 1000V one or two string per inverter. IAC max 50A for one inverter.
Uoc max ≤ 1000V one or two string per inverter. IAC max 50A for one inverter.
| Needs | String junction box | AC Combiner box | ||
|---|---|---|---|---|
| Switchgears and control (Q) | See 10 to 36kW design | |||
| Surge protection (SPD) | • type 2 | • type 1 or 2 | ||
| Enclosure (E) | Outdoor IP5x Double insulation | Standard AC requirement + grid code requirement | ||
| Metering | Energy | P, Q, PF, Energy, Alarm |
Fig. P28 : 150-500kW multi 3-phases inverters
Multi MW Grid connected PV system (Large building and farm)
- Typically 500kW-630kW inverters with LV/MV transformers and MV substation.
| Needs | String | Array junction box | Generator junction box | Inverter | AC box 400V or other voltage (Transfoless inverter) |
|---|---|---|---|---|---|
| Switchgears and control (Q) | |||||
| - Isolation | • | • | • (a) | see PV_monitoring | • |
| - Switching (Making & breaking rated current | • DC22A | • (a) | see PV_monitoring | • | |
| - Control | • (b) | see PV_monitoring | • | ||
| - Over-current protection | • | • (c) | see PV_monitoring | • (f) | |
| - Protection against Insulation fault | • (h) | see PV_monitoring | • (h) | ||
| Surge protection (SPD) | (g) | • type 2 | (g) | • type 1 or 2 | |
| Enclosure (E) | Outdoor IP5x Double insulation | Indoor Double insulation | |||
| Metering | Energy | P, Q, PF, Energy, Alarm, Power quality | |||
(a) PV array main switch is usually included in the inverter panel.
(b) If switching for emergency services is required, the main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing.
(c) Array cable protection is recommended to prevent cable overszing. To ensure fast trip of protections 6 to 8 arrays are recommended.
(b) If switching for emergency services is required, the main switch in array box can be equipped with tripping coil and motor mechanism for remote reclosing.
(c) Array cable protection is recommended to prevent cable overszing. To ensure fast trip of protections 6 to 8 arrays are recommended.
(f) Overload and short-circuit protection.
(g) If there is no SPD in the inverter or if the between DC box and inverter >10m a SPD is necessary in this box.
(h) Galvanic insulation is provided by LV/MV transformer,
(g) If there is no SPD in the inverter or if the between DC box and inverter >10m a SPD is necessary in this box.
(h) Galvanic insulation is provided by LV/MV transformer,
- PV system without functional earthing: insulation monitoring is necessary: IMD - IM20 and accessory IMD-IM20-1700
- PV system with functional earthing: the earthing shall be done with a DC MCB breaker (C60PV 4P series 2 – 10A) or a fuse.
Fig. P29 : 500-630kW inverters with LV/MV transformers
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