Photovoltaic system: electrical equipments selection

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)<nr>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

(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

Fig. P23 : 10-100kW single multi MPPT inverter