4.5kW SolarEdge/LG System coming soon to San Diego

[LouieA]

At the risk of asking a question that has been asked a million times before, what are the advantages of a power optimizer + string inverter over multiple micro-inverters?

It seems to me that the biggest risk to using micro-inverters is their reliability. Although recent technology my increase their life to 25 years, many in the past haven't lasted longer than five years; requiring the labor associated with getting on a roof and pulling an inverter that's underneath a low panel. Perhaps they are more expensive than power optimizers and inverter?

So, power optimizers have a 25 year warranty like micro-inverters. Has their technology been proven over time?

I found the following:

http://www.solarelectricsupply.com/solar-inverter/microinverters-optimizers

http://www.energymatters.com.au/renewable-news/em3495/

In summary, Optimizers are less costly than Microinvertors but are not as scalable.
Also, I understand that MicroInvertors may not be as reliable and have more parts which increases the mean time between failure.

[thejq]

I found the following:

http://www.solarelectricsupply.com/solar-inverter/microinverters-optimizers

http://www.energymatters.com.au/renewable-news/em3495/

In summary, Optimizers are less costly than Microinvertors but are not as scalable.
Also, I understand that MicroInvertors may not be as reliable and have more parts which increases the mean time between failure.

If by scaleable you meant economy of scale, you got the opposite. The initial cost of SE inverter + single optimizer is much more than a single microinverter. But the incremental cost of microinverter is much more than optimizer. So eventually the cost of SE inverter + optimizers will be less as the system size grows. In my case, at 4.8KW, they were roughly the same.

[LouieA]

If by scaleable you meant economy of scale, you got the opposite. The initial cost of SE inverter + single optimizer is much more than a single microinverter. But the incremental cost of microinverter is much more than optimizer. So eventually the cost of SE inverter + optimizers will be less as the system size grows. In my case, at 4.8KW, they were roughly the same.

Actually meant scalable in the sense that if later down the road you want to add to more panels in the future MicroInverters will allow you the flexibility to do so. In terms of cost it really depends on system size. Smaller systems will be most cost effective using MicroInverters.

[thejq]

Actually meant scalable in the sense that if later down the road you want to add to more panels in the future MicroInverters will allow you the flexibility to do so. In terms of cost it really depends on system size. Smaller systems will be most cost effective using MicroInverters.

Got you. With SE, if you plan to expand later, you just have to get a slightly larger inverter to begin with. The price incremental is not that bad, eg. from SE5000 to SE6000 is about $100. With optimizer you can add panels with different brand and wattage just like microinverter. With microinverter, you still need to plan ahead if you want to add more later. Because microinverter always output 240v, the more you add, the higher the current going to the main breaker panel. So you need to start with larger gauge wire for expansion later. With optimizer, the DC voltage will increase as you add more panels, so the DC current only increases slightly, and you save a little bit on wiring.

[subdriver97]

Actually meant scalable in the sense that if later down the road you want to add to more panels in the future MicroInverters will allow you the flexibility to do so. In terms of cost it really depends on system size. Smaller systems will be most cost effective using MicroInverters.

Depending on the initial size of your solar system and the capacity of the SE Power Inverter installed, a good number of additional panels can be added.

Real World case: I will be installing a 4.5kW system, namely 15 LG300 panels and a SE5000 inverter with a max rating of 6.75kW. This gives me the capacity to add 2.25kW or an additional 50% to system capacity. An option that I'm considering is paying the $135 difference between a SE5000 & SE6000 to bump inverter to a max rating of 8.1kW. This would increase expandability to add 3.6kW or an additional 80% to system capacity. I can see in the future adding two EVs and a pool to my home. I've heard 4 panels to support an EV. Anyone have an idea on additional capacity to support a pool pump?

As far as cost numbers. Assuming $130 per M250 and $1450 for a SE6000 and $70 per DC optimizer. Doing the math on 130x = 1450 + 70x. I work it out that the crossover point is at 24 panels. So assuming 300W panels that's a 7.2kW System. So:
< 7.2kW Enphase M250 will be cheaper
> 7.2kW SolarEdge will be cheaper
(Note: that SolarEdge system is limited to 8.1kW with a SE6000, but the same calculation can be done for a SE7600 and higher rated SolarEdge inverters)

[subdriver97]

Actually meant scalable in the sense that if later down the road you want to add to more panels in the future MicroInverters will allow you the flexibility to do so. In terms of cost it really depends on system size. Smaller systems will be most cost effective using MicroInverters.

The other consideration with regard to system expansion is that the net metering rules are only going to allow you to increase your system size by 10%.

[lkstaack]

As far as cost numbers. Assuming $130 per M250 and $1450 for a SE6000 and $70 per DC optimizer. Doing the math on 130x = 1450 + 70x. I work it out that the crossover point is at 24 panels. So assuming 300W panels that's a 7.2kW System. So:
< 7.2kW Enphase M250 will be cheaper
> 7.2kW SolarEdge will be cheaper
(Note: that SolarEdge system is limited to 8.1kW with a SE6000, but the same calculation can be done for a SE7600 and higher rated SolarEdge inverters)

Another important criteria though is reliability. Has your research identified a clear leader in that area? My quick research indicates that optimizers have fewer components, suggesting that they would be more reliable. Do statistics back that up?

[subdriver97]

Another important criteria though is reliability. Has your research identified a clear leader in that area? My quick research indicates that optimizers have fewer components, suggesting that they would be more reliable. Do statistics back that up?

Neither SolarEdge or the Enphase M250 has been on the market for very long (<2 yrs), so I wouldn't say there is a definitive leader with regards to reliability. Both manufactures are providing warranties for 25 years (whatever that is worth). My vendor told me that he hasn't seen a single failure with SolarEdge systems that they have installed, but note that is a sizable but limited sample size. Enphase had significant problems with their micros early on but word on the street is that the newer ones are more reliable. Someone posted something that other day though that showed that Enphase is losing significant money to warranty claims. An optimizer is considerably simpler than a micro inverter. The key is that the component that generates heat is moved to a central inverter vice on the roof in the hot sun. Personally, I don't see any advantage to micros over SolarEdge. When you throw in that you get free monitoring with SolarEdge and you avoid the problems with the Enphase Envoy Communicator, it was enough for me to pay a little more to get SolarEdge.

[Bikerscum]

Depending on the initial size of your solar system and the capacity of the SE Power Inverter installed, a good number of additional panels can be added.

Real World case: I will be installing a 4.5kW system, namely 15 LG300 panels and a SE5000 inverter with a max rating of 6.75kW. This gives me the capacity to add 2.25kW or an additional 50% to system capacity. An option that I'm considering is paying the $135 difference between a SE5000 & SE6000 to bump inverter to a max rating of 8.1kW. This would increase expandability to add 3.6kW or an additional 80% to system capacity. I can see in the future adding two EVs and a pool to my home. I've heard 4 panels to support an EV. Anyone have an idea on additional capacity to support a pool pump?

As far as cost numbers. Assuming $130 per M250 and $1450 for a SE6000 and $70 per DC optimizer. Doing the math on 130x = 1450 + 70x. I work it out that the crossover point is at 24 panels. So assuming 300W panels that's a 7.2kW System. So:
< 7.2kW Enphase M250 will be cheaper
> 7.2kW SolarEdge will be cheaper
(Note: that SolarEdge system is limited to 8.1kW with a SE6000, but the same calculation can be done for a SE7600 and higher rated SolarEdge inverters)

Be careful with the max input values for the Solaredge inverters. Because you can input 6.75k into a 5kw inverter doesn't mean you get that same percentage out it just means you can do that without burning it up. You'll find the max continuous output is 5.4k if I recall correctly.

[sensij]

Be careful with the max input values for the Solaredge inverters. Because you can input 6.75k into a 5kw inverter doesn't mean you get that same percentage out it just means you can do that without burning it up. You'll find the max continuous output is 5.4k if I recall correctly.

In southern CA, the max allowed by SolarEdge is a 1.25 ratio, so that would be 6.25 kW into a 5 kW inverter. In cooler parts of the country, 1.35 is allowed. At a 1.35 ratio, in the areas it is allowed, clipping loss might be around 1% of annual production, while at a 1.25 ratio in the warmer zones, it is probably less than 0.5%. More information on this is available from their site, I'm too lazy to link it at the moment.

I would guess that their thermal modeling indicates that the inverter duty is high enough at a 1.35 ratio to have a material impact on the system life in higher temp areas of the country, but they don't really go into detail.

[subdriver97]

Will update as they come...

Was contacted by the vendor and have a site survey (measure roof and such) scheduled for this coming Friday afternoon 12/5/14.

It was suggested that one way to cut costs may be to consider installing LG270 or LG280 instead of LG300. I've asked the vendor to consider this and let me know if the price difference is worthwhile. I will most likely do it if is greater than $500 difference. Over the life of system the expected loss in efficiency due to the slightly older technology will essentially be negligible. It would mean another ~$0.10/W decrease in price...

[subdriver97]

Got you. With SE, if you plan to expand later, you just have to get a slightly larger inverter to begin with. The price incremental is not that bad, eg. from SE5000 to SE6000 is about $100. With optimizer you can add panels with different brand and wattage just like microinverter. With microinverter, you still need to plan ahead if you want to add more later. Because microinverter always output 240v, the more you add, the higher the current going to the main breaker panel. So you need to start with larger gauge wire for expansion later. With optimizer, the DC voltage will increase as you add more panels, so the DC current only increases slightly, and you save a little bit on wiring.

Thejq, Since you mentioned the main breaker panel. I was wondering what size breaker do you have on your SE6000? I'm wondering if the breaker size would be different for SE5000 vs SE6000.

[LouieA]

subdriver97 and theJQ,

First, thanks for forwarding over your installer information. I called them and received a very competitive quote.

I plan to talk with them tomorrow and when I do I am going to inquire about their choice of hardware for roof mounting / flashing. Did you by chance ask them? If so, would you please share?

Have heard great things about a product called Quick-Mount PV which is supposedly the best in the industry. I'm hoping that they use this product.

[subdriver97]

subdriver97 and theJQ,

First, thanks for forwarding over your installer information. I called them and received a very competitive quote.

I plan to talk with them tomorrow and when I do I am going to inquire about their choice of hardware for roof mounting / flashing. Did you by chance ask them? If so, would you please share?

Have heard great things about a product called Quick-Mount PV which is supposedly the best in the industry. I'm hoping that they use this product.

I didn't ask about the specific mounting hardware. I just verified that they install double flashings. I don't know anything about the Quick-Mount PV. It's probably more important whatever they used is installed correctly than the specific design/brand of the hardware. But let me know what they say when you ask, you peaked my curiosity.

It all gets done pretty fast. If you youtube solar installations, for an average home-size installation a typical installer will have the stanchions and rails in place in less than an hour and the panels mounted in about 2 hours.

[subdriver97]

After ~1.5 months of research and estimates from 6 vendors. I came to agreement on price with a vendor today. System specs are:

System Size: 4500 kW
Panels: 15 LG300
Inverter: SolarEdge SE5000
Total Cost $18005 (includes $2500 service panel upgrade)

PV System Cost (pre-tax credit) = $15505 ($3.45/W)

As promised, I got a quote on LG280 in place of LG300 as follows:

System Size: 4480 kW
Panels: 16 LG280
Inverter: SolarEdge SE5000
Total Cost: $17344 (includes $2500 service panel upgrade), difference of $661

PV System Cost (pre-tax credit) = $14844 ($3.31/W)

The vendor gave me these expected production numbers:
My understanding is that the difference is based on the nameplate difference and the 1% less linear warrantied performance of the LG280s
15 LG300 / 4500kW : 7192 kWh
16 LG280 / 4480kW: 7078 kWh

Comparing ratios ( LG280 to LG300)
Nameplate: 4480/4500 = 99.56%
Production: 7078/7192 = 98.41%
Cost: 14844/15505 = 95.74%

Looking at the ratios it looks like a sound financial decision to go with the LG280s.

I'd really like comments/feedback on the LG280s vs. LG300s