Effects of clouds on your array? I'm considering SMA's Secure Power Supply inverters.

[huge]

Can you plug the SPS into a wall outlet to get electricity in the entire house? Not to power everything, but just vital essentials like refrigerator and AC. Some people can't move the refrigerator to the SPS to plug it in and it would be much more convenient to just plug the thing in one outlet and get power to other parts of the house

[SunEagle]

The new SunnyBoy models (only the 5000w and 6000w have been released as of May 2016), have up'd the SPS spec to 2000w, so I think SMA has responded to the naysayers that claim it won't power very much. I agree with you that this feature gives this product a big advantage over the competition and I'm surprised no one else has copied it.....

The biggest issue with the SMA product is that most places when the grid goes down it is due to bad weather and clouds. Therefore no sun.

Now if you live in an area where there are brown outs or rolling black outs a system like the SMA will certainly help you with some power to run critical loads. I just wouldn't bank on that power being there all the time when the grid goes down.

[solarix]

The new SunnyBoy models (only the 5000w and 6000w have been released as of May 2016), have up'd the SPS spec to 2000w, so I think SMA has responded to the naysayers that claim it won't power very much. I agree with you that this feature gives this product a big advantage over the competition and I'm surprised no one else has copied it.....

[nomadh]

Thread resurrection time. I was searching for more information about the sunnyboy sps system when I ran across a very good question by some sharp guy about sps usage. I was finishing reading the post when I realized it was me this was a year and a half ago and was just hearing about this intriguing new product. I was reading because I was just experimenting with my new sunnyboy 7000tl. I'm amazed at how little info there still is on this amazing product . I have 5760 watts of LG panels on my roof now.
I've done few tests now. One was an end of day test at about 8pm. And I was generating only 100 watts. I plugged in a 60 watt light and it powered up no problem. I checked on it until it was 75 and it still powered the 60. Later I saw the light was off and the panels were down to 50 and the inverter was periodically trying a restart. Don't know exactly how much headroom it needed to power 60 watts but I'd call it good. Today I ran our older less efficient fridge. It has a start surge of about 500 watts and run about 300. It kicked on and ran just fine. I still say this is genius. Also the original reports were that this system had 0 surge capability but now I'm hearing there is some reasonable amount.
I just tried to stress test it by running the fridge near end of day. My panels were showing about 350 w when I started but I couldn't get it to fire up. My guess is it couldn't get past the 500 surge startup so I waited to long. I'm estimating that as long as the panels were still kicking out 1kw I could get it to work. If I wanted to maximize it I'd set the fridge controls on max and let it run at it nominal compressor setting of about 200w until the panels ran down to where there wasn't enough headroom. Be pretty good to have ac and fridge during a few summer brownouts. If something longterm happened that 1500 watts a day or 15 kwh a day would be nice.

[inetdog]

The inverter does not indicate how much is available, only instantaneous consumption/power generated. The invert display shows the MPPT channels voltage and amp draw from each of the strings, which adds up to the instantaneous consumption.

By looking at the actual panel voltage versus the theoretical Vmp for the panel temperature you can get some idea of the amount of "reserve" power in the panels. When the SPS is delivering the maximum possible output for the conditions, the Vmp x Imp product multiplied by the SPS efficiency will be the power you are drawing.
Since in the absence of partial shading the array Vmp is relatively independent of the amount of light on the panels, you will know it as that SPS draw on the panels approaches the maximum available.
The maximum current, Imp, on the other hand is almost directly proportional to the amount of light over a wide range. Most of the time the GTI function will be drawing Imp while the SPS function will be drawing less, as needed to supply the output demand, moving the operating point to a higher voltage.

[NKetch22]

Thank you very much for your report of actual usage of the Secure Power feature. Yours is one of the only actual reports I've seen, and if you make any other experiments I would be very interested in hearing about them. While you were running these things, did the inverter say how much power was actually available from the panels? Or does it only say how much you are drawing?

Today, which was a mostly sunny day, I managed to run a small beverage refrigerator from the SPS. Last time the inverter refused to provide sufficient power when the compressor kicked on. Granted, the normal power consumption of the fridge is only 0.85 amps @ 115v...Othewise, I have only maxed out the SPS at about 500 watts.

Once the grid interconnection is approved and net meter added I will try and formulate a correlation of the full PV system output into the grid vs. the SPC output.

The inverter does not indicate how much is available, only instantaneous consumption/power generated. The invert display shows the MPPT channels voltage and amp draw from each of the strings, which adds up to the instantaneous consumption.

[home4]

This is not true. I just had my 5.889 kW system installed with an SMA Sunny Boy 6000TL-US-22 with Secure Power. While I await my new meter, I have played with the secure power. I took a sick day last week on an overcast cloudy day. For kicks I decided to plug in a jig saw. I ran it flawlessly for a few minutes. I then decided to run an extension cord from the secure power outlet to my entertainment center. Since both items were the only draw on the system, the Sunny Boy display lists the draw coming from the secure power. Running the jig saw for a minute was a 500 watt draw. The tv/cable box/sound bar was a 450 wall drawing which was maintained for about three hours until night was starting to fall upon the panels. The constant cloudiness kept the power at a constant rate and did not result in any shutdown/restarts until it got late. If you overload the secure power it will restart itself on it's own. No going back to the switch.

So in summation; I think the secure power supply is a great add-on. With occasional hurricanes and blizzards, I just need enough power to charge phones, laptops and perhaps run a tv or bring the internet up for a little while.

Thank you very much for your report of actual usage of the Secure Power feature. Yours is one of the only actual reports I've seen, and if you make any other experiments I would be very interested in hearing about them. While you were running these things, did the inverter say how much power was actually available from the panels? Or does it only say how much you are drawing?

[nomadh]

This is not true. I just had my 5.889 kW system installed with an SMA Sunny Boy 6000TL-US-22 with Secure Power. While I await my new meter, I have played with the secure power. I took a sick day last week on an overcast cloudy day. For kicks I decided to plug in a jig saw. I ran it flawlessly for a few minutes. I then decided to run an extension cord from the secure power outlet to my entertainment center. Since both items were the only draw on the system, the Sunny Boy display lists the draw coming from the secure power. Running the jig saw for a minute was a 500 watt draw. The tv/cable box/sound bar was a 450 wall drawing which was maintained for about three hours until night was starting to fall upon the panels. The constant cloudiness kept the power at a constant rate and did not result in any shutdown/restarts until it got late. If you overload the secure power it will restart itself on it's own. No going back to the switch.

So in summation; I think the secure power supply is a great add-on. With occasional hurricanes and blizzards, I just need enough power to charge phones, laptops and perhaps run a tv or bring the internet up for a little while.

There are a few reports on the web like yours. I too am very tempted by this feature even though string inverters seem completely wrong for my roof. The reports I've seen claim its very linear. It seems as long as your 5.9 wk system is just limping along even at 1.7 kw you can still heat 1.5. and even into the night or storms if the system is making say 1k you can use 7 or 800 watts it seems.

btw enphase has their answer here http://enphase.com/wp-uploads/enphas...Brochure-1.pdf
10 yr 1.2 kw modular battery plugnplay. Kinda poor substitute but if its 10 years and the inverter only lasts 10 years. its an answer to backup islanding.
Any guesses how much?

[NKetch22]

Is this true in your experience? This is the exact question I have been seeking to get answered in this thread. I have seen this repeated elsewhere, that if a small cloud comes in the output from the Secure Power Supply would go off. But it doesn't seem to me like this would be the case. Say I have a 6 kW PV array and the Secure Power Supply, there is an outage and I'm drawing 500W powering some loads. The Secure Power Supply would not go off unless it is no longer able to produce that 500W AC, which means that the array would need to be producing maybe 800W DC (or not even). In your experience, if a cloud goes over your array will its output drop by 85% (6kW to 800W)? I'm not trying to argue this point -- I really do not know if it would, as I do not currently have a solar PV system, but I'm looking to find out that answer because this seems to be key in how well this system would work. When I read online about the effect of cloud cover on PV it seems as though the entire sky would have to be quite cloudy for it to drop that much.

For me personally, I'm interested in this system because I want SOME sort of backup in case of a long-term power outage. I have a generator, and that is very useful, but I have friends who went without power for 2 weeks a couple of years ago, and it would be really really nice to have even a little power for things like lights, radio, phone, etc, during a time like that. During Hurricane Sandy, gas was nearly impossible to come in certain areas. A PV solution would not provide power during the storm, but in the aftermath, it could be very useful.

It would be great to have a fully islanding system with batteries during a time like this, but unfortunately it seems like these systems are really really expensive. Unless there is an inverter I haven't read about, even without batteries they are expensive because the inverters cost so much more, and they usually restrict the panels you can get.

The Secure Power Supply seems to me like it provides some of the benefits of an islanding system, with a lot less cost, and also more restrictions. But with a UPS and a generator, it seems like it could be a good choice, and that's why I'm interested in finding out more about it. Thanks.

This is not true. I just had my 5.889 kW system installed with an SMA Sunny Boy 6000TL-US-22 with Secure Power. While I await my new meter, I have played with the secure power. I took a sick day last week on an overcast cloudy day. For kicks I decided to plug in a jig saw. I ran it flawlessly for a few minutes. I then decided to run an extension cord from the secure power outlet to my entertainment center. Since both items were the only draw on the system, the Sunny Boy display lists the draw coming from the secure power. Running the jig saw for a minute was a 500 watt draw. The tv/cable box/sound bar was a 450 wall drawing which was maintained for about three hours until night was starting to fall upon the panels. The constant cloudiness kept the power at a constant rate and did not result in any shutdown/restarts until it got late. If you overload the secure power it will restart itself on it's own. No going back to the switch.

So in summation; I think the secure power supply is a great add-on. With occasional hurricanes and blizzards, I just need enough power to charge phones, laptops and perhaps run a tv or bring the internet up for a little while.

[russ]

I believe that the efficiency of both micro and string inverters have gotten at least a bit more efficient the last few years.

Marketing hype and BS for a great part

[nomadh]

Pardon? Upped the advertising maybe - the game though - how?

I believe that the efficiency of both micro and string inverters have gotten at least a bit more efficient the last few years. That older report mentioned earlier made it look like string inverters would need to get about 20% more efficient and have not heard that. For instance has anyone seen a 20%+ efficiency increase from the older model sunnyboy to the newer?

Sunnyboy claims its new power point tracking technology still collects 99% of the unshaded string output, not the Volts but the power . This would seem to make very similar output to enphase or solar edge. I'm still not convinced and see no tests to prove or disprove it..

https://www.youtube.com/watch?v=bxIi4GiZakE

[russ]

Hopefully all of those real world conditions. I looked at the report you mention and it looks like a report designed to put string inverters out of biz. The microinverters trounced the older style in shaded and unshaded tests. Hopefully newer string inverters have upped their game. Have any of the more long time experienced installers seen the line inverter companies bring their power production per panel up at least 20% on unshaded installs over the last few years let alone shaded? And even then the newest microinverters have also upped their game.

Pardon? Upped the advertising maybe - the game though - how?

[nomadh]

Under what assumptions? Perfectly sunny? Predictable AM clouds? Partial shade? Perfectly south panel orientation at latitude tilt? The level of granularity you are looking for will be very installation specific. You could spend some time setting up your conditions in SAM and see if you get different results with different inverters.

Here is one study, using older equipment in 2011. The technology for both kinds of inverters has improved since then.

Hopefully all of those real world conditions. I looked at the report you mention and it looks like a report designed to put string inverters out of biz. The microinverters trounced the older style in shaded and unshaded tests. Hopefully newer string inverters have upped their game. Have any of the more long time experienced installers seen the line inverter companies bring their power production per panel up at least 20% on unshaded installs over the last few years let alone shaded? And even then the newest microinverters have also upped their game.

[sensij]

Don't know how real any of the info is but it seems plausible. So you are saying the optitrac is pretty much what most of the other string inverters are already doing? It seems sunnyboy is claiming the technology gets them into the ballpark of power op modules or even microinverters. The info I'm looking for now is a head to head of sunnyboy optitrac vs microinverter vs solar edge.

Under what assumptions? Perfectly sunny? Predictable AM clouds? Partial shade? Perfectly south panel orientation at latitude tilt? The level of granularity you are looking for will be very installation specific. You could spend some time setting up your conditions in SAM and see if you get different results with different inverters.

Here is one study, using older equipment in 2011. The technology for both kinds of inverters has improved since then.

[inetdog]

Don't know how real any of the info is but it seems plausible. So you are saying the optitrac is pretty much what most of the other string inverters are already doing? It seems sunnyboy is claiming the technology gets them into the ballpark of power op modules or even microinverters. The info I'm looking for now is a head to head of sunnyboy optitrac vs microinverter vs solar edge.

No, let me make this more explicit.
I have no idea what algorithms any other string inverter manufacturers use. Any of them might be using an algorithm that handles shaded panels fine but only scans at 5 minute intervals (not so good for intermittent shade) or might be doing just as well as Optitrac, or might be behaving even worse than SMA without Optitrac.

What I am trying to say is that without that information (which does not seem to be easy to get), you cannot use the existence of Optitrac alone as a competitive feature against all other string inverters.

As for doing as well as micros or optimizers, that is very hard to do in practice because those two will be able to actually capture power from partially shaded panels, while Optitrac can at best find the mixed string MPPT with no output at all coming from the shaded panel sections or panels.
If you have more than one string with unequal shading between them, then the combination of Optitrac with two or more independent MPPT inputs is what you will need.
PS: Which is exactly the combination that SMA is providing in its newer inverter models.