Evaluate - Off grid with no batteries - SMA Sunny Boy 5.0 + 9 Suniva 340 Watt Panels

[jflorey2]

I want to create an off-grid setup designed to function without batteries or an energy storage mechanism. I recognize this system will not function in inclement weather or nighttime. I know that most inverters will end up creating AC that is much too "dirty" (erratic sine wave; although I don't really understand that concept) to power high demand or more sensitive electronics.

Most modern inverters (TSW) produce pretty high quality power.

Could this one inverter coupled with nine panels and bit of sunshine give me a zero maintenance standard 110 AC outlet that could power devices as wide in range from my table saw to my computer without issue?

No. It will not start your saw. The system you describe would likely work for things like laptops; their power requirements are low, they are not very "surgey" and they have their own batteries to hold up the device when AC goes out. It would also work to charge batteries. But it won't start most motors.

I look forward to your replies and as a side note, if the setup seems effective for its proposed usage, how should I alter the setup for any potential partial shading issues? Are microinverters even usable in this kind of a setup?

No, not really.

Finally, does anyone have any experience with the SMA units to know if this kind of setup risks potentially damaging the inverter? (I would be using the Sunny Boy 5.0 so the total Wattage input should be well within range for the whole device - I am a bit concerned about using the SPS function as an always on outlet)

The SMA inverters are quite good at protecting themselves, so that would be the least of my worries.

If money is no object, then build a standard system (panels/charge controller/inverter) using ultracaps. The ultracaps will function like a (very small) battery and let you start bigger loads. You will still lose power when the sun goes behind a cloud, but it will likely be more reliable overall. And ultracaps last 10 years or so; longer if you don't care about capacity (which you don't.) A 130 farad 56 volt cap from Maxwell will run you about $1200, and such a system will give you 2000 watts for about 30 seconds - more than enough to start most 120 volt tools.

[SunEagle]

Thank you gentlemen for your input. It has been educational and productive. I have emailed SMA with some questions pertaining to our discussion and when I get a reply I will certainly share it. The surge demand is definately an issue with my higher load devices, I suppose the only solution without a battery would be to double the panels get two Sunnyboys and connect the two SPS outlets in paralell to provide a roughly 4000 Watt dedicated outlet. It know it might seem a bit absurd to some of you but from a theoretcal perspective it should work should it not?

Unfortunately you can't parallel those outlets to increase the power supply for a load. They aren't designed that way.

I am afraid if you want to power a big load for short times then you will have to either get a generator or a battery system. Since it won't be for long duration then neither would need to be big. Just sized for your large loads like your table saw.

The other problem is that the SPS option on the SMA inverter is not something that works continuously. It has to be reset every day and if there is even a few moments of no sunlight you lose even that little bit of power. IMO a pain in the butt.

[ButchDeal]

I suppose the only solution without a battery would be to double the panels get two Sunnyboys and connect the two SPS outlets in paralell to provide a roughly 4000 Watt dedicated outlet. It know it might seem a bit absurd to some of you but from a theoretcal perspective it should work should it not?

NO! not in a fictional way, nor theoretical or literal would it work.

Why are you so dead set on not having batteries? A Bimodal system with batteries would work and be much more useful.

Also why are you so dead set agains grid tie? that would be the most (and likely) only cost effective solution for you.

[sensij]

Thank you gentlemen for your input. It has been educational and productive. I have emailed SMA with some questions pertaining to our discussion and when I get a reply I will certainly share it. The surge demand is definately an issue with my higher load devices, I suppose the only solution without a battery would be to double the panels get two Sunnyboys and connect the two SPS outlets in paralell to provide a roughly 4000 Watt dedicated outlet. It know it might seem a bit absurd to some of you but from a theoretcal perspective it should work should it not?

No, you can't connect two SPS outputs together. They would not have any way to synchronize phase (among other problems).

[Crom]

Thank you gentlemen for your input. It has been educational and productive. I have emailed SMA with some questions pertaining to our discussion and when I get a reply I will certainly share it. The surge demand is definately an issue with my higher load devices, I suppose the only solution without a battery would be to double the panels get two Sunnyboys and connect the two SPS outlets in paralell to provide a roughly 4000 Watt dedicated outlet. It know it might seem a bit absurd to some of you but from a theoretcal perspective it should work should it not?

[SunEagle]

Crom. The simple answer is without a grid or batteries your plan to use the SMA with the SPS option will not work to run your saw. Sorry. It just does not work that way.

[ButchDeal]

Butchdeal - The answer to your last question is above. As for the table saw I have a jet pro tools table saw. It runs off a standard 110 volt 15amp circuit (and that circuit isn't even dedicated). The SPS generates 2000 watts worth of AC. Watts/Volts=Amperage. So my 2000 Watt SPS receptacle / 110 standard voltage = 18.18 Amps. My calculations show I should have more than enough power. Is my math or thinking wrong somehow? As for always on, my understanding is the SPS is on as long as the system is not sensing power from the grid. Assuming I never attach it to the grid, it should then always be on whenever the sun is shining (although I have received conflicting info on whether I have to reset the actuator switch every day).

Please keep critiquing gentlemen, I would rather find the problem now, than after install. Thanks again.

There is nothing but problems with your system design. It is extremely unlikely that the table saw will start with out tripping the inverter as well.
the sos is on only when it is turned on and even if the grid is on it will stay on till it trips and has to be reset. Cloud goes by reset.
table saw start surge will trip it.

Most portable table saws are 13a or 15a, stationary are 18a or larger. all will require at least 150% amp draw to start for a few seconds. Not enough to trip a breaker but the SPS can not provide any surge power so it trips off.

[solar pete]

As far as i know the sunny boy wont work without a grid

[sensij]

Sensij - I might be wrong but I believe that the Sunnyboy 3.0 has an secure power supply of only 1500 watts and that it only gets to 2000 watts at the sunnyboy 5.0 and above. That's primarily why I chose it. Secondarily I chose a higher rated inverter because since I plan on using a much higher wattage worth of panels (close to 3000) to insure the SPS outlet works on cloudy days, I didn't want to risk overpowering the inverter on bright sunny days when all the panels are working at max output. Let me know if you see a flaw in that thinking. Also could you post a link to learn more about the "Tigo" devices you referenced?

The 2000 W SPS is a feature of the 1SP-US-40 series of inverter. The TL-US-22 series had the 1500 W SPS. The new series launched with just the 5.0 and 6.0 kW inverters, but has since expanded to cover the entire 3.0 to 7.7 kW range. You can put at least 3750 W on a 3000 W inverter safely, maybe more depending on how the panels are oriented.

Keep in mind that if you arrange half your panels east and half west, you'll get a lower, broader peak than you would from a typical southerly orientation. A split array will produce less energy than a south facing array of the same size, but flattening out the peak to get more hours above 2000 W may be more suited to your purpose than just raw energy production. Again, experiment with PVWatts.

I think you'll have real problems if you try to use the SPS as a standard outlet, the very least of which will be resetting it each morning. I'm not sure you will even be able to get though commissioning of the inverter, to make the SPS available at all.

Check out PVOutput.org and find a system in your area to get a feel for what output on a typical day looks like.

[Mike90250]

Plain PV panels have no "surge capability" Starting any motor requires a surge capability of several times running power. in otherwords, it's unlikely the saw will run, It will likely crash the inverter. You may be able to "blip" start the saw with quick "blip" applications of power to get the motor spun up to speed, and then it may be happy.

Solar panels in shade/cloudy conditions, produce less that 10% of nameplate power.

[Crom]

Sensij - I might be wrong but I believe that the Sunnyboy 3.0 has an secure power supply of only 1500 watts and that it only gets to 2000 watts at the sunnyboy 5.0 and above. That's primarily why I chose it. Secondarily I chose a higher rated inverter because since I plan on using a much higher wattage worth of panels (close to 3000) to insure the SPS outlet works on cloudy days, I didn't want to risk overpowering the inverter on bright sunny days when all the panels are working at max output. Let me know if you see a flaw in that thinking. Also could you post a link to learn more about the "Tigo" devices you referenced?

Butchdeal - The answer to your last question is above. As for the table saw I have a jet pro tools table saw. It runs off a standard 110 volt 15amp circuit (and that circuit isn't even dedicated). The SPS generates 2000 watts worth of AC. Watts/Volts=Amperage. So my 2000 Watt SPS receptacle / 110 standard voltage = 18.18 Amps. My calculations show I should have more than enough power. Is my math or thinking wrong somehow? As for always on, my understanding is the SPS is on as long as the system is not sensing power from the grid. Assuming I never attach it to the grid, it should then always be on whenever the sun is shining (although I have received conflicting info on whether I have to reset the actuator switch every day).

Please keep critiquing gentlemen, I would rather find the problem now, than after install. Thanks again.

[ButchDeal]

I am a bit concerned about using the SPS function as an always on outlet)

What exactly do you mean by "Always on Outlet"
The SPS is in no way Always on, or even mostly on. In fact you could quite literally call it Mostly Off

Also unless you have a quite small table saw, I doubt it will start with SPS.

Why are you planning to use a 5kw inverter with only 3kw of solar?

[sensij]

You can use PVWatts to estimate the number of hours during the day your system is capable of producing the 1000 W you desire (look for the hourly output link once you go through the basic model run). Keep in mind that the SPS requires a manual switch be actuated each day, and possibly in other conditions with intermittent power availability.

For the array you've suggested, the SMA 3.0-US would give you the same output as the 5.0, but costs less. It sounds like you are suggesting the system will not be hooked up to the grid at all. I have no idea if that will work. I doubt it would hurt the longevity of the inverter, if it does.

Microinverters are not compatible with the SMA system. You could consider Tigo devices if you want the panels to be "optimized". SMA has an online design tool that can make a recommendation for the specific arrangement you are considering.

[Crom]

Thank you SunEagle,

Sorry about the multiple submissions. I thought for some reason my posts were not getting posted. I didn't realize the weblink restriction. Thanks for the clarification and help. I look forward to the feedback.

[SunEagle]

Hello Crom and welcome to Solar Panel Talk

All of your posts went to our unapproved section due to them having weblinks. I approved this one and soft deleted the rest as duplicates.

I am sure you will get some feed back on your question now that your posts can be seen.