Need your opinion again. LG System 3.3K W

[Itsme]

As for which inverter, I think brand-wise, they're both good. What you want to look for is whether one is transformer or transformer-less (TL). TL is probably more desirable because they're lighter, don't generate as much heat, and don't hum. They're probably a newer design with a nice graphical display (I have an SMA 4000TL). With a TL type, you can probably even install it inside your garage (for more security) if you want without much issue because it doesn't heat up your garage and make noise.

Another key thing to look for is the warranty length between the inverter brands. They range anywhere from 5 to 20 years, depending on the market/buyer/option choice. Ask your contractor what they offer and if there's any difference between the SMA or PowerOne.

Question pls: Is SMA the same thing as Sunnyboy?

[Volusiano]

Question pls: Is SMA the same thing as Sunnyboy?

Yes, SMA is the manufacturer name. Sunnyboy is the string inverter model name.

[haizman]

Which Inverter?

If you have different angles and some shading to consider, have you thought about paring the LG panels w/ Enphase microinverters or SolarEdge power optimizers?

I had a 4.7 kW system installed recently (16 x LG 295 NIC-G3 and SolarEdge SE5000 inverter w/ power optimizers on every panel). So far I've been producing around 25% more than the CSI Calculator's estimated production...I hope that continues throughout the year! So anecdotally I can say this combination is a good paring.

[Volusiano]

If you have different angles and some shading to consider, have you thought about paring the LG panels w/ Enphase microinverters or SolarEdge power optimizers?

I had a 4.7 kW system installed recently (16 x LG 295 NIC-G3 and SolarEdge SE5000 inverter w/ power optimizers on every panel). So far I've been producing around 25% more than the CSI Calculator's estimated production...I hope that continues throughout the year! So anecdotally I can say this combination is a good paring.

Most calculators and even contractors give conservative estimates as a general rule of thumb. For example, PVWatts uses a very conservative 0.77 derate factor by default. So your beating the calculator's estimate may not necessarily be due to your pairing winning combination, just due to the conservative estimates from the calculators.

Besides, the OP has already decided on string inverter and is only asking for opinions between PowerOne and SMA string inverter choices.

[J.P.M.]

If you have different angles and some shading to consider, have you thought about paring the LG panels w/ Enphase microinverters or SolarEdge power optimizers?

I had a 4.7 kW system installed recently (16 x LG 295 NIC-G3 and SolarEdge SE5000 inverter w/ power optimizers on every panel). So far I've been producing around 25% more than the CSI Calculator's estimated production...I hope that continues throughout the year! So anecdotally I can say this combination is a good paring.

1.) Your high numbers may be somewhat attributable to what I've observed is a rather common practice among vendors - they unpredict performance to sell larger systems. Part of this is due, IMO, to the low #'s that PV Watts starts with and what those #'s mean - that type of info being what more than a few vendors conveniently forget to educate consumers about, not that most customers care or even understand. For those consumers who do - I apologize. But then, no one to my experience, ever got fired for selling too much. Solar vendors are in business to make money - not necessarily sell cost effective systems. I get that. I guess one result is that customers somehow feel like they got a deal and that may be true to a point, except that often the point of cost effective sizing is easily, conveniently and effectively left behind. Caveat Emptor.

2.) Now that three ft. ridge setbacks may come to pass, it may not be quite as easy to oversize systems. One drawback may be that it could give Sunpower dealers an advantage when pitching those customers who already swallow the Sunpower prattle about area effficiency being somehow magically and inexplicably linked to cost effectiveness.

3.) FWIW, for Haizman's situation, the #'s I got from my weather station and system monitor lead me to believe that Dec. in n.c. San Diego was about average sunshine wise, the last half being sunnier than the 1st half. I'm about 10-15 miles from San Marcos. The average clearness index I recorded for calendar Dec. was about .607. The same clearness index using TMY data for MCAS Miramar calc's out at about .605 for an "average" or "typical" TMY Dec. I estimate my system should produce about 600 kWhrs. for calendar Dec. with TMY weather. The actual from the system monitor was 590 kWhrs.with some minor late P.M. shading so those #'s seem mostly reasonable to me. It's probably a coincidence that the month's actual irradiance was close to what a "TMY" month would have been. I wouldn't normally expect such close #'s.

[silversaver]

Yes, technically they can install more on the back side of my house but it won't get full exposure. The estimated 13 are areas where it would get 85-97% sunlight according to their measurements. Even my neighbor who just had Solar City install Trina panels for a 4kW system couldn't get much more panels on just the fact how our homes are facing and limited roof space.

So I signed for the LG system. My next question is, should I go with Power-One or Sunnyboy Inverter (w/the built in outlet)? Also, any pros or cons having the conduits run outside of the house vs. attic run?

I do think micro inverters are better choice for you, just in case if you want to expand the size (easier).... Power one and SMA are both good transformerless inverters with dual mpp trackers. With SMA 4000TL, you can utilize the dual mpp trackers by using 2 strings with min. of 5 panels per string. (125V min DC) I run my SMA 6000TL inverter in my garage. It isn't hot as other older design transformer inverter. SMA is little smaller with emergency power plug and newer design from SMA

http://www.sma-america.com/en_US/products/grid-tied-inverters/sunny-boy/sunny-boy-3000tl-us-3800tl-us-4000tl-us-5000tl-us.html

[advan24r]

My roof absolutely has no space for microinverters especially with the city's 3 ft clearance. So my only options is the sma inside my garage.

[silversaver]

My roof absolutely has no space for microinverters especially with the city's 3 ft clearance. So my only options is the sma inside my garage.

micro inverters do not need any extra spacing, they sit under the panels.

[advan24r]

micro inverters do not need any extra spacing, they sit under the panels.

Then I think it must have been the added cost that deterred me from going with it.

[Volusiano]

I do think micro inverters are better choice for you, just in case if you want to expand the size (easier)....

I'm not sure why microinverters would make the expansion easier, unless you just want to add another few panels at a time. But why would you want to add only a few panels at a time knowing that the cost in permit and fees would not make this expansion sensible?

A more sensible expansion to me would be to add in another 3K or 4K worth of panels at a time, not just 1K worth. And if you go for another 3-4K worth of panels to justify the fees/permit cost, you can easily tie them up to another 3-4K string inverter just the same.

[silversaver]

I'm not sure why microinverters would make the expansion easier, unless you just want to add another few panels at a time. But why would you want to add only a few panels at a time knowing that the cost in permit and fees would not make this expansion sensible?

A more sensible expansion to me would be to add in another 3K or 4K worth of panels at a time, not just 1K worth. And if you go for another 3-4K worth of panels to justify the fees/permit cost, you can easily tie them up to another 3-4K string inverter just the same.

He has very limited roof space + he has a small 3.3kW system, so I figure no way he can add 3kW or even 2kW later but few extra panels might be possible for him on other roof with shading..... Wait a year or 2, there might be a 400W+ panels available and he can add few more panels there + it is harder to find a string inverter less than 2kW. No way that he can just add few panels with string inverter less than 2kW Agree?

The SMA did came out the Sunny Boy 240-US micro inverter which can be add-on to a string inverter with a Multigate technology, but it is only rate at 240W... so.... anyway, just a suggestion and I could be wrong.

[Volusiano]

He has very limited roof space + he has a small 3.3kW system, so I figure no way he can add 3kW or even 2kW later but few extra panels might be possible for him on other roof with shading..... Wait a year or 2, there might be a 400W+ panels available and he can add few more panels there + it is harder to find a string inverter less than 2kW. No way that he can just add few panels with string inverter less than 2kW Agree?

OK, I understand your rationale better now. So the key thing you're saying is to wait a few years for 400+W panels to add on to the rest of the limited roof space. The problem is that if the tax credit doesn't get renewed after 2016, there may not be incentive enough for him to go for 400+W panels anymore.

Plus if I remember correctly, he considered SunPower panels but in the end decided to go with LG panels, so I'm not sure if roof space is really the key limitation here or not. It looks like cost also plays a big factor as well.

At any rate, I just heard a lot about micro-inverters being easier to expand, which is true in theory if you're allowed to incrementally add on a panel or two at a time. But in reality you can't add on a panel or two at will without the hassle and cost redoing the whole permit process all over again. So in general it may sound good in theory but in reality it's not practical anyway, so I just wanted to point this out.

[silversaver]

OK, I understand your rationale better now. So the key thing you're saying is to wait a few years for 400+W panels to add on to the rest of the limited roof space. The problem is that if the tax credit doesn't get renewed after 2016, there may not be incentive enough for him to go for 400+W panels anymore.

Plus if I remember correctly, he considered SunPower panels but in the end decided to go with LG panels, so I'm not sure if roof space is really the key limitation here or not. It looks like cost also plays a big factor as well.

At any rate, I just heard a lot about micro-inverters being easier to expand, which is true in theory if you're allowed to incrementally add on a panel or two at a time. But in reality you can't add on a panel or two at will without the hassle and cost redoing the whole permit process all over again. So in general it may sound good in theory but in reality it's not practical anyway, so I just wanted to point this out.

I totally agree with you especially after such a long period of time to complete the solar system. I'll suggest if he ever think to expand the solar, he is better off doing it now than later. He only has the space for 11 panel, so he choose LG 300W panels to save the cost. If is was me, I'll go with SP 345W panels. Since it is a smaller system, you won't really feel the price difference. Those 345W panels perform really well. I have seen few system output outstanding results. The older E 18 and E 19 panels were so so not really worth the extra $$$.