Technical data

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Sine Wave Inverters

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Key:

A Solar module

B Solar charge controller

C Battery

D Steca Solarix PI sine wave inverter

E Steca PAx4 parallel switch box

F Generator junction box

G Electrical load (230 V-)

Steca Solarix PI with

Steca Tarom

Communication with Steca Tarom solar charge

controllers

A further innovation that has gone into the Steca Solarix PI

is the communication with the solar charge controllers from

the Steca Tarom and Steca Power Tarom series. A data con-

nection to the charge controller can be created via the Steca

PAx4 parallel switch box.

In this case, the inverter connected directly to the battery

communicates the amount of energy that has been with-

drawn to the solar charge controller. The controller is thus

able to calculate the correct state of charge (SOC).

This means that these systems no longer need to be swit-

ched to voltage-controlled operation or an additional current

shunt.

If the switch-off threshold of 30 % SOC is reached, the Steca

Solarix PI receives a signal from the solar charge controller

and subsequently switches itself off in order to protect the

battery from deep discharge. It turns itself back on again on-

ce the SOC has reached the 50 % mark.

2 3 4 5 6 7 8 9

Master Slaves

AC Master

AC Slave

Data Tarom

Data Slave

Data Master

Data Slave

550 VA / 12 V

1,100 VA / 24 V

1,100 VA / 12 V

2,200 VA / 24 V

1,650 VA / 12 V

3,300 VA / 24 V

2,200 VA / 12 V

4,400 VA / 24 V

Steca Solarix PI:

flexible and versatile

Parallel connection

A stand-alone PV system is relatively difficult to size, since

often the loads and their average running times are not ade-

quately known, or because, when the system is subsequently

expanded, more loads are added.

This is where the simple expandability of the Steca Solarix

PI inverters pays off. Up to four devices can be operated in

parallel. The connections are made via an external box, the

Steca PAx4.

From the outside, the combination of two, three or four in-

verters functions like one device with a correspondingly hig-

her capacity. Internally, in case of open-circuit operation or

low output, e.g. for the lighting, only one inverter continues

to operate. This has a positive effect on the electricity con-

sumption, since the devices which are not turned on do not

consume any power. Only when a higher capacity is called

for, for example when a refrigerator is turned on, are all the

inverters automatically switched on, thus ensuring trouble-

free operation.

In this regard, Steca Solarix PI inverters are all the same. Only

via the connection to the Steca PAx4 parallel switch box is one

inverter designated as the master. This device then has cont-

rol over the system, whilst the other Steca Solarix PI inverters

operate as slaves.

Rotary switch

Operating the Steca Solarix PI is made very easy by the large

rotary switch on the front of the device.

If the Steca Solarix PI is being used as a single device, three

different modes of operation are possible, and these may be

selected using the rotary switch. The load detection section

follows on from the ‘off’ setting on the far left. In this sec-

tion, the switch can be turned continuously to match the

power consumption of the smallest load. In order to reduce

power consumption, the inverter is then turned off, and it

checks periodically whether a load has been turned on. Only

if this is the case does the inverter switch itself on. The ‘on’

setting on the rotary switch follows on from the load detec-

tion section. In this operating status, the inverter makes the

output voltage continually available.

If several inverters are connected in parallel, the desired mode

of operation is selected using the rotary switch of the device

connected to the ‘master socket’. In addition to the modes of

operation described above, there is also the setting ‘all on’.

This means that not only the master device is continually swit-

ched on, but all other connected inverters as well.

The use of the rotary switch makes it possible to see very quik-

kly which mode of operation the inverter is in.

Electronic fuse

One innovation in sine wave inverters is the electronic fuse

as it is employed by Steca in solar charge controllers. With

this fuse, the Steca Solarix PI is protected against overloads,

and also against the accidental connection of the AC output

to the public grid. Because the fuse is electronic, it does not

need to be replaced after it has been triggered, as is the case

with mechanical fuses. As soon as the problem has been re-

medied, the inverter automatically reverts back to its selected

mode of operation.

The Steca Solarix PI is also internally protected against an in-

correct wiring of the battery. In case of reverse polarity, the

device remains undamaged, and there is no need to replace

the fuse.

Quick and robust control

The Steca Solarix PI inverter was developed to supply power

to a wide range of loads. Even critical loads can be operated,

thanks to the quick control. At the heart of the controller

is a DSP which takes on the extensive calculation work. The

inverter’s necessary robustness is supplied by a control soft-

ware program which was developed in cooperation with a

renowned research institute..

Low own consumption

In die Entwicklung des Sinus-Wechselrichters sind 15 Jahre

The sine wave inverter has benefited from Steca’s 15 years of

experience in the field of stand-alone PV systems. This is re-

flected, for instance, in the low own consumption of the Ste-

ca Solarix PI. When used in solar home systems, the inverter

is connected to the battery 24 hours a day, and is designed

to consume as little as possible of the solar-generated energy

whilst in load-detection or open-circuit modes.