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Reviews Categories | Emergency/Portable Power: generators, solar, wind, thermal, etc | Steca Sigma Help

Reviews Summary for Steca Sigma
Steca Sigma Reviews: 1 Average rating: 5.0/5 MSRP: $(missing—add MSRP)
Description: Steca’s Solarix series is the world’s most sold PV charge controller for the use in medium sized solar home systems and PV power supplies in the range of 8 to 30 Amp (up to 900 Wp). The heart of the controller is the integrated circuit called ATONIC®, which contains the regulation software based on a self learning algorithm. The result is an accurate state of charge (SOC) metering of the battery, the best insurance for a long battery lifetime.

• PWM shunt battery charging
• state of charge (SOC) battery regulation
• boost charging
• equalising charge
• float charging
• automatic load reconnection
• automatic selection of voltage (12 V / 24 V)
• temperature compensation
• positive grounding
• (or) negative grounding on one terminal
• field adjustable parameters by jumpers on PCB
• option: operates load only by night
Product is in production.
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K0JEG Rating: 5/5 Jul 1, 2007 08:53 Send this review to a friend
invisible  Time owned: 3 to 6 months
I recently upgraded my solar array and needed a new controller. My old system was <20Ahr, and had the Steca Solsum. As I increased loads I kept popping the fuse, and didn't get very good runtime. I then upgraded to the Sigma, which can handle loads of up to 20A.

I had a little trouble finding out about this controller, as it is distributed in the US by Sunwise solar. A little Googleing around led me to the German manufacturer. I'm still a bit of a novice when it comes to solar power, but this seems to be a good unit (although not necessarily the cheapest). I am using it with 6X15 Watt harbor freight panels and 2X100AHr gell cells. You have to set jumpers in the unit to select the correct battery type. If you have normal lead acid cells it will periodically perform an equalization charge to mix the electrolite. Since I have gells, I disabled this function. The controller will cut out the load if the charge falls below 11.1VDC. It will also compensate for temperature. It also has a dusk to dawn function, if you want to use it to power lights. It will also work on 24V systems.

For the most part, just plug everything in and it goes to work. I've been experimenting with different loads to see what all can be powered by the system, and I have confirmed the low voltage cutoff works as advertised (HI HI). The state of charge LED gives a quick indication of (what else?) the charge state of the batteries. Green is good, yellow - between 11.7 and 13.7, red - below 11.7, flashes red below 11.7 and low voltage cutoff. Will automatically power on again when charge is above 12.6VDC. There is an optional LCD display and a PC interface, which I do not have.

Construction is good, with the back being metal and acting as a heat sink. The plastic cover pops off easily before you wire everything up (the wires help keep the lid on, kind of strange but it works). The wiring is all screw terminals, which can handle up to 8 gage wire, according to the manual.

The manual says it will adjust itself to the battery's state of charge and discharge rate over time. I have removed one of the batteries since it never seemed to get to full charge with 3 (due to the panels), and it did show some strange behavior for a few days (staying red longer than it had before), so I think it must be doing something.

Works well, somewhat expensive, but it should keep the batteries in good shape for a long time.


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