Poly vs mono and SMA vs Enphase

[cyph]

Today was a sunny but overcast day. The string inverter system which normally exceeds the micro system by 2 kwhr on a clear sunny day produced 26.94 kwhr. The micro system produced 28.4 kwhr. That is about 3.5 kwh reversal. It's not as extreme as two days ago. This may be more inline with the norm for cloudy days. I believe there are benefits to micros for days with shades. It's impossible to quantify based on the extremely limited sample size. I will revisit this after three months to see how the systems compare.

[cyph]

Yesterday was an all around ugly day with no sun. String inverter system got 11.28 kwh and the micro got 10.6 kwh. This seems to confirm they share the same weather system. Without any sun whatsoever, I'm not surprised the string got better results as it normally does. Today will be another cloudy day but hopefully not as bad as yesterday. I'd like to see how they do with some sun among the clouds.

[cyph]

Interesting! Not one of my quotes had the micro-inverters less than the regular inverters!

I have a flat roof, south facing... so the only shade "MIGHT" come from my chimney on the west side of my home....

The lower cost was between different installers rather than quotes from the same installer. You could find an installer that prefer micro as they are easier to install. They may knock off part of the install cost to cover the added cost of the micros. In California where Enphase dominates, some installers may be getting incentives to push Enphase.

[craeay]

I have a tall palm tree on the east side and a small palm tree on the west side. My panels are on the west side and it gets hit with shades early morning between 10-12. It gets also get shades after 5PM. My satellite dish on my chimney (had I known I would install solar there, I would've asked them to move the dish). For 30 minutes, one panel is shaded. With a central inverter, the production for my entire array would collapse with one panel shaded.

Today is another cloudy day and I will report the production tonight. It could be that yesterday was an anomaly as losing 30% on cloudy days whereas the micro lost perhaps 5% seems odd. As for micro, the quote I received for the install of my system was lower than the other quotes for string inverters so there is no cost differential. All the benefits are gravy. I was able to track production on a per panel basis which allowed me to trim some tree branches that increased an additional .5-1 kwhr after 5PM. I am in the process of calling DirecTV to move that dish to another location. The difference is probably neglible with the micros, but I'm in the new shiny thing phase where I am trying to get the optimum production possible even with the early morning and late afternoon shade issues.

On a normal clear day, the string inverter system (with no shades) produces 30-33 kwhr whereas the micro produces 29-31 kwhr even with the early and late afternoon shades. Microinverters get a thumbs up from me.

Interesting! Not one of my quotes had the micro-inverters less than the regular inverters!

I have a flat roof, south facing... so the only shade "MIGHT" come from my chimney on the west side of my home....

[cyph]

Wow! Thanks for the info! I guess the bigger question is: If you assume that this is 'average' for your two systems, how long will it take to recover your additional cost of installing microinverters instead of regular inverters? Anything AFTER recoup of initial cost differential is the 'gravy'.

I have a tall palm tree on the east side and a small palm tree on the west side. My panels are on the west side and it gets hit with shades early morning between 10-12. It gets also get shades after 5PM. My satellite dish on my chimney (had I known I would install solar there, I would've asked them to move the dish). For 30 minutes, one panel is shaded. With a central inverter, the production for my entire array would collapse with one panel shaded.

Today is another cloudy day and I will report the production tonight. It could be that yesterday was an anomaly as losing 30% on cloudy days whereas the micro lost perhaps 5% seems odd. As for micro, the quote I received for the install of my system was lower than the other quotes for string inverters so there is no cost differential. All the benefits are gravy. I was able to track production on a per panel basis which allowed me to trim some tree branches that increased an additional .5-1 kwhr after 5PM. I am in the process of calling DirecTV to move that dish to another location. The difference is probably neglible with the micros, but I'm in the new shiny thing phase where I am trying to get the optimum production possible even with the early morning and late afternoon shade issues.

On a normal clear day, the string inverter system (with no shades) produces 30-33 kwhr whereas the micro produces 29-31 kwhr even with the early and late afternoon shades. Microinverters get a thumbs up from me.

[craeay]

Update on this. Today was a cloudy day. The microinverter system gave me 29 kwhr and 5 miles away, the Aurora (I thought it was SMA but it's actually Aurora) inverter was only able to achieve 23.6 kwhr. This system has no shades and routinely hit 30-32 kwhr on a clear day. I think for days like these the microinverters are far more efficient.

Wow! Thanks for the info! I guess the bigger question is: If you assume that this is 'average' for your two systems, how long will it take to recover your additional cost of installing microinverters instead of regular inverters? Anything AFTER recoup of initial cost differential is the 'gravy'.

[cyph]

Great apples to oranges comparison

Why do say that? The shades from the clouds is obviously affecting the string inverters efficiency. The homes are 5 miles apart so both are under the same weather system.

[russ]

Update on this. Today was a cloudy day. The microinverter system gave me 29 kwhr and 5 miles away, the Aurora (I thought it was SMA but it's actually Aurora) inverter was only able to achieve 23.6 kwhr. This system has no shades and routinely hit 30-32 kwhr on a clear day. I think for days like these the microinverters are far more efficient.

Great apples to oranges comparison

[cyph]

Update on this. Today was a cloudy day. The microinverter system gave me 29 kwhr and 5 miles away, the Aurora (I thought it was SMA but it's actually Aurora) inverter was only able to achieve 23.6 kwhr. This system has no shades and routinely hit 30-32 kwhr on a clear day. I think for days like these the microinverters are far more efficient.

[inetdog]

No question about shade affecting production after 5 PM - only the insolation level is low at that time so it makes little difference.

Kind of like 10% of not much is still not much.

San Jose is near the western edge of the Pacific Time Zone, and with Daylight Savings Time in effect, the amount of insolation left at 5pm is a little bit more than you might otherwise expect. There are several hours of the early evening left before the sun gets really low in the sky.
Still, nowhere near the effect as the same sort of shade at noon.

[russ]

Well here it is. Proof that shades affect my production after 5PM.
[ATTACH=CONFIG]2857[/ATTACH]

No question about shade affecting production after 5 PM - only the insolation level is low at that time so it makes little difference.

Kind of like 10% of not much is still not much.

[cyph]

Well here it is. Proof that shades affect my production after 5PM.
enphase.jpg

[cyph]

Awesome calculator! It predicts that I get 18.5 kwhr on average. With E6 it should cover 86% of my bill. The weird thing is that with a HELOC it predicts 5.6 year payback whereas cash purchase is 6.8 years. I'm not sure how it figures that.

In either case, both systems are handily beating the estimate. I expect 28 kwhr average for eight months and 15 kwhr daily for four winter months would still exceed the 18.5 kwhr daily by a healthy margin.

[russ]

Play with the Sharp calculator - it lets you adjust most things http://sharpusa.cleanpowerestimator.com/sharpusa.htm

Gives you an idea

[cyph]

It's southwest facing. Is 29-31 kwhr for a 5kw system below average in Northern California? The system is producing 850 this past month.