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

[inetdog]

It may be hard for you to understand why a solar pv system needs to be shut down when the grid goes down. The reason is to protect the people that work on the Utility's electrical equipment from getting electrocuted. Sure it doesn't make sense that you lose your ability to generate power from your solar panels but how much do you really need during a power outage which probably happens when there is a storm and clouds.

If it is important to have power then get a whole house generator and a big propane tank. Relying on solar as a power backup source is expensive and intermittent at best.

In my opinion, the more important reason that a Grid Tie solar system needs to be shut down when the grid goes down is that the design of the inverter simply does not allow standalone operation.
The SPS inside a SunnyBoy is a separate inverter, and one which is designed slightly differently from a typical off grid inverter so that it can operate directly off the panels without needing batteries as an energy buffer.
A single inverter design which can both operate independently AND synchronize its output to a grid connection, as found in some hybrid inverters, is more expensive, and that is reflected in the price of those units.

[SunEagle]

This sunny boy system really fills a niche it seems. Thanks for mentioning it. I've been looking at solar for 2 years now and one thing that really irritated me was that during a power outage my solar system would produce 0 power. Not just less than optimum, not 50% not even 20%. Thats was just crazy. This 6k inverter being able to provide 1.5 k in an emergency is really sweet. Did the OP end up using the sunny boy? Did it cost much more than other inverters or even microinverters?
Please let us know.

BTW I've lurked a few days but this thread is the one that got me to sign up.

It may be hard for you to understand why a solar pv system needs to be shut down when the grid goes down. The reason is to protect the people that work on the Utility's electrical equipment from getting electrocuted. Sure it doesn't make sense that you lose your ability to generate power from your solar panels but how much do you really need during a power outage which probably happens when there is a storm and clouds.

If it is important to have power then get a whole house generator and a big propane tank. Relying on solar as a power backup source is expensive and intermittent at best.

[thejq]

Sunnyboy with SPS is nice to have but it's a niche at best. Seriously how often do you think you will use it even during power outage. 1. it has to be during the day. 2. < 1500 watts of power. 3. can be plugged into it without too much hassle. So you can't run a refrigerator off it, because of too much load and far away in the kitchen. Lights? well it's in the day so no need. Internet modem/router? Yes, that's important, but again the modem/router needs to be in the garage which's not common in most homes. The only practical usage is for powering portable devices like cell phone, radio, small appliances or a small TV. FWIW, I think a few large UPSs and plugin rechargeable flashlights will serve your emergency needs much better, day or night. Selecting inverters based on SPS or not, it's like picking jewelries based on how nice the box is.

[sensij]

This sunny boy system really fills a niche it seems. Thanks for mentioning it. I've been looking at solar for 2 years now and one thing that really irritated me was that during a power outage my solar system would produce 0 power. Not just less than optimum, not 50% not even 20%. Thats was just crazy. This 6k inverter being able to provide 1.5 k in an emergency is really sweet. Did the OP end up using the sunny boy? Did it cost much more than other inverters or even microinverters?
Please let us know.

BTW I've lurked a few days but this thread is the one that got me to sign up.

It seems like a great idea, but you might want to really think through what your implementation would look like. You almost need to have it charging a UPS for it to do any good at all, which means your critical circuits need a way to be transferred from grid power to the UPS at the appropriate time. If you go without a UPS, you'll still need some kind of transfer switch (the SPS doesn't plug into your main electrical panel), and you are relying solely on what the sun can provide, limiting the generation to the peak time of day, and hoping there are no clouds.

How long is your typical power outage? How often do they occur? What do you intend to keep powered?

[home4]

Did the OP end up using the sunny boy? Did it cost much more than other inverters or even microinverters?

I have not purchased anything and won't be able to until next year, but I am in the research phase right now. It seems to me that the Sunny Boy w/ Secure Power Supply is a little more expensive than some other string inverters (but not much) and is cheaper than microinverters. So I'm interested in it, but would love to hear from someone with first hand experience with the product.

[nomadh]

This sunny boy system really fills a niche it seems. Thanks for mentioning it. I've been looking at solar for 2 years now and one thing that really irritated me was that during a power outage my solar system would produce 0 power. Not just less than optimum, not 50% not even 20%. Thats was just crazy. This 6k inverter being able to provide 1.5 k in an emergency is really sweet. Did the OP end up using the sunny boy? Did it cost much more than other inverters or even microinverters?
Please let us know.

BTW I've lurked a few days but this thread is the one that got me to sign up.

[inetdog]

If I recall, the SPS outlet, has to be turned on manually every time it resets.

Not quite.
Every time the grid comes back, the SPS has to be turned off to enable GTI and then when the grid goes away again the switch has to be thrown to re-enable the SPS.

But if the load exceeds solar contribution or the panel power goes away completely the SPS shuts down but will periodically try to start up again without any additional switch action.

[control4userguy]

If I recall, the SPS outlet, has to be turned on manually every time it resets.

That's right- switch-over is completely manual on a SMA TL. I like the UPS idea even though it probably wouldn't work for those with exterior GTIs.

[Mike90250]

If I recall, the SPS outlet, has to be turned on manually every time it resets.

[home4]

That's basically what I was thinking of too -- it seems like the cheapest way of having some sort of small "off-grid backup" system, charge the ups with utility power when available, switch to the secure power supply when that goes down, if the UPS gets low and secure power supply isn't enough then get out the generator, that way you don't have to run a generator for small loads. I'm just trying to estimate how much power the secure power supply would actually be able to give.

To clarify, I meant to charge the UPS from the secure power supply when the grid is down, unless it couldn't keep up in which case you could fire up a generator.

[home4]

There is a lot to be said for finding a UPS that could be powered by the SPS and having that plugged in. That should stabilize the output somewhat on days with passing clouds

That's basically what I was thinking of too -- it seems like the cheapest way of having some sort of small "off-grid backup" system, charge the ups with utility power when available, switch to the secure power supply when that goes down, if the UPS gets low and secure power supply isn't enough then get out the generator, that way you don't have to run a generator for small loads. I'm just trying to estimate how much power the secure power supply would actually be able to give.

[peakbagger]

There is a lot to be said for finding a UPS that could be powered by the SPS and having that plugged in. That should stabilize the output somewhat on days with passing clouds

[home4]

If the panel output never dropped below 400W, then you could probably run a 200W resistive load off the SPS.
The amount that your array output drops on a bad day depends on your local weather, panel type and orientation, and so much else that I am not willing to make any predictions.

Thanks

[inetdog]

I don't really want to power a space heater Just giving an example of a fixed load, like 200W. That's what I'd like to know, would a 6000W array be able to power a 200W load on a cloudy day without interruption? Or would this not be possible?

If the panel output never dropped below 400W, then you could probably run a 200W resistive load off the SPS.
The amount that your array output drops on a bad day depends on your local weather, panel type and orientation, and so much else that I am not willing to make any predictions.

[home4]

No way would you be able to power a space heater on a cloudy day, IMHO. Although they do make some pretty small (200W) space heaters.

I don't really want to power a space heater Just giving an example of a fixed load, like 200W. That's what I'd like to know, would a 6000W array be able to power a 200W load on a cloudy day without interruption? Or would this not be possible?