Solar energy - Priority No.1
With today's environmental concerns and energy sources becoming scarce, there is growing interest for photovoltaic systems. Approximately 15,000 times of current global electricity consumption could potentially be produced from solar radiation. A possible application for this energy source lies in PV solar modules on private houses and also in large high power installations.

Core components for solar systems
In addition to the popular Solarlok interconnection systems for PV solar modules, TE Connectivity supplies a number of other core components for solar systems. Relays are an important part, after all "solar electricity only enters the electricity network over relays". Feeding energy into the national electricity network is subject to special rules and standards and special requirements apply to the relays used.

Photovoltaic solar energy systems consist of a PV-generator (solar modules) and a power inverter with a connection to the power line. The advantage of these systems is that the solar energy can be fed into the public power grid and energy can be taken out of the network if necessary. It is precisely at the feed-in interface to the power grid that electromechanical relays find their main application area. Safety measures require an automatic switching unit with a circuit break function between the generating equipment and the feed-in point into the power grid.

The relevant switching units must comply with DIN standard V VDE V 0126-1-1 from 02.2006. The most important specification contained in this standard is that a contact gap of W 1.5mm is required at each switched pole.

The automatic switching units are usually integrated into the inverters of PV systems. Each pole requires two switches mounted in series. At least one of the two switches must be configured as a relay or as a circuit breaker. This means that for PV systems with galvanic isolation and single-phase AC feed-in at least two normally open relay contacts are needed, one each for the phase L and neutral line N lines.

For PV systems with no galvanic isolation, both of the switchesmounted in series must be electromechanical components. In any case, the circuit separation must be achieved via four electromechanical contacts, two for L and two for N lines. Three-phase systems will need, accordingly, a higher number of contacts. Depending on circuit design and test algorithms, it is also possible to use configurations where the contacts operate simultaneously, e.g. 2 changeover relays with one contact for the separation of the L and one for N line.

Depending on system power and type of feed-in, a continuous current rating of up to 26 A is required, e.g. for 6 KWp and single-phase feed-in. This is the typical upper limit for small systems such as those aimed at single family houses. For large-scale installations, inverters with substantially higher feed-in currents are needed.

Part Number	View Inventory
1721929-1 Solar Relays
2027395-1 Solar Relays