6Kw going in soon in Aliso Viejo

[Alisobob]

So..... some neighbors came over last night for Christmas dinner. One was a friend who did solar about 8 months ago. Same size system ( 24 panels x 270 watt monos) Same south facing roof, about 1/4 mile away... same weather. His output? Crap.

default2.JPG


My output from the same day...

13th.JPG

The only difference between our two systems? I have micro inverters, and he has a central inverter.

His installer told him the central inverter was the way to go, but also warned him that some.. "small shading issues would impact his fall / winter output."

He said his output was ok in the summer, but fall has crippled his output, and winter will be much of the same.

One tree shading his property was an existing neighbors tree, the other is a common area tree, also existing. There is nothing he can do in that regard.

He contacted his installer, who stated the crippled output... " is more than they expected... sorry."

So now he is considering replacing the central inverter, with micros.

I know Micro's are often frowned upon... but if you find yourself in a situation where you're deciding which way to go... dont make the mistake my neighbor did.... or have the original installer put in writing how much the output will fall off in fall / winter months.

My friend is really sad he ever got involved in solar, and that sux...

[J.P.M.]

So..... some neighbors came over last night for Christmas dinner. One was a friend who did solar about 8 months ago. Same size system ( 24 panels x 270 watt monos) Same south facing roof, about 1/4 mile away... same weather. His output? Crap.

[ATTACH=CONFIG]5443[/ATTACH]


My output from the same day...

[ATTACH=CONFIG]5444[/ATTACH]

The only difference between our two systems? I have micro inverters, and he has a central inverter.

His installer told him the central inverter was the way to go, but also warned him that some.. "small shading issues would impact his fall / winter output."

He said his output was ok in the summer, but fall has crippled his output, and winter will be much of the same.

One tree shading his property was an existing neighbors tree, the other is a common area tree, also existing. There is nothing he can do in that regard.

He contacted his installer, who stated the crippled output... " is more than they expected... sorry."

So now he is considering replacing the central inverter, with micros.

I know Micro's are often frowned upon... but if you find yourself in a situation where you're deciding which way to go... dont make the mistake my neighbor did.... or have the original installer put in writing how much the output will fall off in fall / winter months.

My friend is really sad he ever got involved in solar, and that sux...

FWIW, members, posters and lurkers take a lesson here. Learn what your getting into before you get sold a bill of goods. Do your homework. It's too bad this happened but it is not uncommon. Looks like Alisobob's neighbor got screwed, partially due to peddlers selling product without concern for the particulars and partly due to the neighbor's lack of due diligence. Caveat Emptor. Maybe output will improve as we get past the solstice and the annual output will not be as bad as the deep winter output would lead one to believe. Let's hope.

[Alisobob]

.... partially due to peddlers selling product without concern for the particulars and partly due to the neighbor's lack of due diligence. Caveat Emptor.

Yup.... Buying a house, a new car, and solar are things seldom done more that once by the average human. You are un-armed, and ripe for the picking.

Do as much homework as you can, and level the playing field.

I got a good education here at S-P-T.

You can too.....

I'll let you know how this works out for my friend.

[sensij]

Yup.... Buying a house, a new car, and solar are things seldom done more that once by the average human. You are un-armed, and ripe for the picking.

Do as much homework as you can, and level the playing field.

I got a good education here at S-P-T.

You can too.....

I'll let you know how this works out for my friend.

I think buying microinverters in your friend's situation would be throwing good money away. I would suggest that he look into Tigo optimizers. Most of the existing wiring and the inverter can be kept intact, and they cost ~$50 / panel + $335 for the controller and gateway. With some creativity, it might be possible to install them on just the panels that receive shade.

[Alisobob]

I'll pass this info on. Thanks.

[sensij]

I'll pass this info on. Thanks.

You're welcome! I honestly can't tell from the graphics you attached by how much their system is underperforming. Their morning usage was low, but their evening usage was much higher than yours. Depending on what time they started adding all that load, it looks like the systems might have been close in performance. For example, over the noon hour, you had something like -3.0 kWh of generation of net usage, against energy usage that looks like it might have been 1.6 kWh. That is 4.6 kWh total generation. Your neighbor's system had maybe -1.2 kWh of net usage, against usage that might have been around 3.6 kWh. That gives 4.8 kWh PV generation.

Before your neighbor spends any money on system changes, I would encourage a better analysis of the numbers to see how much energy is being lost to shade. The same kind of cost analysis that justifies the system in the first place could be used to determine if it is worth it to spend more on upgrades.

[Alisobob]

Y Their morning usage was low, but their evening usage was much higher than yours. Depending on what time they started adding all that load, it looks like the systems might have been close in performance.

I asked him the same thing... he said his load was minimal until around 3pm, when the wife came home to get a dinner party started.

His 9am to 2 pm generation numbers are what have him concerned.

[control4userguy]

Certainly dismal yield from a substantial investment. Just up the coastline from you on a dual string inverter system. 4MPPTs handling different characteristics of the complete system. Same date yield, approx. same household load thoughout the day.

[J.P.M.]

I think buying microinverters in your friend's situation would be throwing good money away. I would suggest that he look into Tigo optimizers. Most of the existing wiring and the inverter can be kept intact, and they cost ~$50 / panel + $335 for the controller and gateway. With some creativity, it might be possible to install them on just the panels that receive shade.

FWIW, I'd generally agree on the money part - but not before/until someone gets a reasonable guess/estimate on:
1.) If, as seems likely at this point, the suspected culprit (shading) really is the actual problem, or is there a tech. glitch w/ the equipment, or something else, or all of those things. The obvious suspect at this time seems to be shading, but that may be worth checking out.
2.) If shading is the culprit, what is the likely/estimated annual production and revenue (bill reduction) penalty. For example, if it is shading, but only for, say 8 weeks or so out of the year around the lowest production part of the year ( winter solstice), it may not be worth the cost in treasure, time and hassle.

I'd try to get a better handle on what is lost before I ran off to fix/change anything. Seems to me like that kind of haste and knee jerk reaction lack of planning is part of the what started the problem in the first place.

If the $$ penalty guess works out to be something like $50-$100/yr., the correction, if undertaken at all in the low $$ penalty case, may be entirely different, and have different immediacy than if the penalty is, say, perhaps $500/yr.

One other point: If it is shading, and that shading tends to be dichotomous in nature,- that is, pretty solid over the shaded portion of the array when it does happen, say from a building or very dense vegetation rather than a roof stink vent or a sparsely vegetated deciduous tree, etc, Micros or optimizers may not be as effective as assumed. More "it depends" stuff.

[russ]

Generally, shading before 0900 hours and after 1700 hours (highly dependent on location but 8 hours maybe) is not worth worrying about.

[J.P.M.]

Generally, shading before 0900 hours and after 1700 hours (highly dependent on location but 8 hours maybe) is not worth worrying about.

More FWIW: Further to Russ' point, my shading costs me about 95 kWh/yr. and it is mostly after ~ 1500 solar time about 11/21 - 01/21. Something like 1% of annual production.

[Alisobob]

dec 2014.JPG

dec 2014.2.JPG

solar2.JPG

Forcast was 688 KWh's

Actual was 581 KWh's.

Weather was bad for several days....

Lets wait and see if Jan. can pick up the slack!!!

[control4userguy]

633/684 here. Less than 10% error is pretty darn good in my book.

[silversaver]

Forcast by SAM 575kWh
Actual 555kWh

7.1kW DC SW245 deg with tilt 23 deg

[J.P.M.]

633/684 here. Less than 10% error is pretty darn good in my book.

If you are comparing actual system output to the output of a simulation program such as PVWatts, it's not error - just the result of the difference between what the simulation used for input and reality for the period under consideration. Simulation programs are estimators of performance used mostly for design purposes, not predictors of existing systems' performance.