SMA Secure Power Supply - What Appliances Does It Actually "Back-Up"

BrianRoss · May 2016

I've been doing a bit of research into the SMA Secure Power Supply and wanted to learn more from folks who have installed it. I like that it provides a plug for back-up, though I'm skeptical as to what appliances can actually be run off of that plug at 1.5kW.

My understanding is that it can power a laptop, home internet, or cell charger. And that it CANNOT power a fridge (not even a mini-fridge).

Has anyone tried to power a fridge (either normal fridge, or a mini-fridge) from the SPS? If so, does it work? Would be appreciative if others could provide some perspective here.

MarkC · May 2016

I have used it to charge my 48 volt golf cart with wattages estimated from 500 to 900. The charger is an OEM smart charger that is supplied with the Club Car President model which uses a heavy transformer to reduce the voltage. The in-rush current is likely significant, so I'd suspect that the SPS will start a medium/small refrigerator - but not actually tried it. The main issue is of course that it will only put out watts that are instantaneously being produced by the PV panels (up to 1500 watts) - there is no battery/capacitance backup to smooth the power.

Dave Angelini · May 2016

Actually the new model is "secure" for 2KW. I just helped my brother replace his. It does start the refrigerator an 18 cu. ft. garage unit.
I do not think it would start his 28 Enterprise class reefer or would I want to rely on this, but it is pretty nice as a feature.

MarkC · May 2016

I believe that the "older" line of SB's (3000 - 7700 TL-US) have the 1500 watts SPS - and as Dave has stated, the new SB 5.0 and 6.0 - US have the 2000 watt SPS. Be interesting to know if they are basically the same as far as in-rush/start current capabilities. I'd like to test mine, but the refrigerator is 200 feet from my solar building!

SolarTree · May 2017

The SMA 4000TL-US with 1500W SPS will power a regular side-by-side refrigerator just fine. I power our refrigerator with one inverter and small chest freezer with the other. I can also power other devices at the same time as well. The in-rush does not trip the inverters. I have been wanting to try my well pump with an autoformer but have not gotten to rewiring the well into a new subpanel yet. I think that will be too much. I have a UPS that I setup to put in-line with the SPS so that it will keep the refrigerator running during cloud cover and store the extra during good sun. I have not tried that setup yet. This may be an option to start larger in-rush loads if the UPS is large enough. I wish SMA wold allow multiple units to sync and parallel with 240V output. I would also be nice if you could get access to the available SBS power (the available power drops will less sun so at one point it may be 1500W but during cloud cover it may drop to 200W 100W or none.) Of course what SMA really needs is a 240v Sunny Island or better yet make a hybrid Sunny Boy with Battery support. Not sure why that is not available.

Also with good sun the inverters will put out the 1500W (not one watt more). I tested the SPS initially with oil space heaters up to 1500W. You need to keep it just below 1500W.

MarcF · May 2017

SMA's Secure Power should be able to deliver 1500 Watts (2000 Watts on newer SB inverters) until it can't - ie, insufficient solar irradiance, or excess load. I would say it should handle a smaller or energy efficient refrigerator, but your mileage will vary. It's not really going to back up much when the power goes down during the day. Having said that, after considering the cost of a battery back up solution, I really like this unique feature SMA provides. It's not costly and gives you something when the grid power goes out...

SolarEdge marketed their new HD Wave inverter with this feature as an option. Unfortunately, when they started to ship the HD inverters, that option was not available and I question if it will ever be. Vaporware !

I hope SMA will continue to innovate and make their new inverters with great features like SPS integrated DC disconnects and WiFi. I attended a presentation today about their new Power+ products which provide selective module level optimization (if you have just a few panels getting shading) or full deployment to use Tigo's Cloud Connected Advanced monitoring and rapid shutdown alternative. I was not impressed. This new product is not compatible with Secure Power Supply because it requires AC power! Their rapid shutdown solutions are expensive, time consuming and inconvenient. It is all getting too complicated, with too many parts to set up and install.

wankel7 · March 2020

With the SPS could you wire it into a small generator transfer switch?

SMA Secure Power Supply - What Appliances Does It Actually "Back-Up"

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