7.7kW LG/Enphase System in San Diego

[Alisobob]

solar115.JPG

So, a few weeks ago when my system was clipping, I called my installer. I told him about the clipping issue, and he assured me I would never recoup the lost production value of the clipping with the bigger, M-250's.

He also said to call him back a two weeks, when the clipping stops.

I said "Stop? Its only going to get sunnier?"

He said, "Yea, its also going to get hotter, and the clipping will stop."

Well, he was right ...again

Funny how good installers know their products, inside and out...

[logdin]

I won't question most of your logic: hey, if it makes you feel good why not. But the suggestion that the M250 is in some way "newer technology" is incorrect. Enphase updated the M215 last year to same 4th generation platform as the M250. I suspect the most significant internal difference between the units is the size of the capacitors. And for what's it's worth, the capacitors are the biggest reliability issue and my guess would be the failure rate is higher on the larger ones.

Well I'll have crow for dinner tonight. I did not know about the update. Made me look. http://blog.gogreensolar.com/2014/01...ot-better.html

Looks like M215's got an update in Spring 2014. Thats why we come to this site. To learn. If those had been available at time of my purchase, it might have made a difference, especially if there were a $30 or $40 premium for the M250s. Thanks for sharing.

[Alisobob]

There is a *lot* of misinformation about cost-effectiveness out there. Some of it can be reduced to a math problem with a solution, but some parts of the decision making will require assumptions and guesses about a future that no one knows. I try to help with the math problem portion of it, the rest is for each of us to decide individually.

+2

[J.P.M.]

Maybe I've made the point too sharply. I am not saying "Don't buy M250's." I am saying, "Don't expect the excess energy produced by the M250's over M215's to be worth as much as the price difference between them, when paired with panels per Enphase's design guidelines."

Solar is a big purchase for most people, maybe the biggest they'll make after a house and a car. I think there is value in identifying the most financially cost-effective package, and once it is known, the relative cost and benefit of the options can be evaluated. $400 for peace of mind could be a bargain.

There is a *lot* of misinformation about cost-effectiveness out there. Some of it can be reduced to a math problem with a solution, but some parts of the decision making will require assumptions and guesses about a future that no one knows. I try to help with the math problem portion of it, the rest is for each of us to decide individually.

+1.

A few of us (I'm in that cabal) rant about cost effectiveness. I'd strongly agree that there is a lot of misinformation in that area, some of it self generated by potential users who do not educate themselves in the rudiments of the time value of money, etc.

More misinformation comes from those with money to make by taking advantage of that misinformation, and also potential users general solar ignorance.

Those two seem to come together here. The M250's may well result in more generation than the M215's. There seems to at least be the potential for more power production.

The question of how much more electricity can potentially be generated is technical. The question of how much that potential added generation is worth as a $$ figure is the stuff of financial analysis.

There is, in my mind anyway, no question that the third rail in this decision making - the emotional part - governs. That's probably as it should be.

The sad part, again to me only, is that the logical portions, which can serve to moderate the emotional part, are usually not given serious consideration. IMO, any decision can be reached. Getting informed and then crunching some #'s does not limit choice, it adds information. I'm not sure there is such a thing as too much information - at least for this discussion.

At least the decisions would be more informed. I can't see the harm in that.

[sensij]

These are all intangible reasons. There are many other "intangible" reasons we justify purchases throughout our lifetime.

Maybe I've made the point too sharply. I am not saying "Don't buy M250's." I am saying, "Don't expect the excess energy produced by the M250's over M215's to be worth as much as the price difference between them, when paired with panels per Enphase's design guidelines."

Solar is a big purchase for most people, maybe the biggest they'll make after a house and a car. I think there is value in identifying the most financially cost-effective package, and once it is known, the relative cost and benefit of the options can be evaluated. $400 for peace of mind could be a bargain.

There is a *lot* of misinformation about cost-effectiveness out there. Some of it can be reduced to a math problem with a solution, but some parts of the decision making will require assumptions and guesses about a future that no one knows. I try to help with the math problem portion of it, the rest is for each of us to decide individually.

[tehan]

I won't question most of your logic: hey, if it makes you feel good why not. But the suggestion that the M250 is in some way "newer technology" is incorrect. Enphase updated the M215 last year to same 4th generation platform as the M250. I suspect the most significant internal difference between the units is the size of the capacitors. And for what's it's worth, the capacitors are the biggest reliability issue and my guess would be the failure rate is higher on the larger ones.

[logdin]

Thanks for the great run through. It really puts a point on it.
Funny how you can still be drawn to doing the 250's emotionally even when you see the math.

Lots of things in life dont add up mathmatically. If you're married, it probably doesnt pencil out 50 percent of the time.

Its really more from a "i've done everything I can to feel like "I" made the right decision".

1. The difference for the OP is really less than $15/unit before FTC. After, its $10/unit
2. Its newer technology. Perhaps better reliabilty, and new features that can be added, where the old technology wont support it.
3. you will get some return on the additional cost. How much will never really be known.
4. bragging rights, and having latest and greatest
5. piece of mind. you will not fret over what you might be missing out on if you'd have gone with the bigger units.

I know there are more.

These are all intangible reasons. There are many other "intangible" reasons we justify purchases throughout our lifetime.

Insurance, warranties, latest and greatest, peace of mind, perceived resale value, perceived reliability, etc....

If everyone evaluated all purchases based strictly on math and 3 year ROI, you'd still be buying 5 year old iphone 4's, LCD TV's, and ignore extended warranties (cell phones, TV's, autos, etc..) to name a few. The intangibles add up to peace of mind. I sleep very well knowing my cars are covered for 125k miles for 8 years for practically any failure other than brakes, tires, and oil changes. I know I've used every extended warranty I've ever purchased to more than 3 times what I paid for it.

Should I buy the 2015 model or the 2016 model. Great deal on the 2015, but damn, that new model 2016 looks pretty cool.

Its emotional, and its therapuetic. Not having to worry about, "did I make the right decsion by going the cheaper route"? Should I have gone with the bigger, better, faster, newer?

If we were talking $1500 bucks, I'd say hell no. But $300 on a 15-25k purchase Thats in the noise for the vast majority.

Dont get me wrong, I pride my self on being frugal, and getting the best deal whenever possible. But thats usually on commodity items that I have experience with and know what the risks are. When you are dealing with a purchase that you have no experience with, and are taking advice from strangers; thats where you take everyone's inputs and make your own decsion. Great personal fortitude for saying I've done the math and I trust everyone elses, and I dont think it pencils out for me to spend a few hundred bucks. For me, the price is so small, and the peace of mind so great, i dont even think about it.

[Alisobob]

I say this graph proves the 215 works amazingly well for you.

I'm getting 42 + Kwh's per day off of my 6.4 KW system.

Thats slightly more than 6.6 KwH's output, per nameplate KW.

I'm clipping, but it cant amount to much I guess.....

As least that's what everyone tells me....

[nomadh]

[ATTACH=CONFIG]7059[/ATTACH]

I clip a little with 270 watt Solar World panels, hooked to M215's.

M250's were a little pricier when I did my install, and I was told I would never recoup the price difference....

Now? I may have gone with them.

Its a tough call....

Looks like you barely clipped the nipple. I say this graph proves the 215 works amazingly well for you.

[nomadh]

For real world data, you might want to review the output of this system on PVOutput.org. There are no 92128 systems in Team San Diego, but the system linked is in 92127 and has LG285's paired with M215's, oriented at 180 deg azimuth with a 22 deg tilt.

There will definitely be some clipping... May 10th, for example, shows something like what you might expect to see in springtime. The power output in the middle of the day is capped at 6300 W (28 * 225 W).

Now let's look at what PVWatts would have said about that day. If I enable gridded locations and enter the 92127 zip code for that system, along with 180 deg azimuth, 22 deg tilt, premium, roof mount with 6% loss, and lay the model on top of the actual data from around that time (May 11th, to be exact), we see the following:

[ATTACH]7061[/ATTACH]

PVWatts seems to have expected a little bit more morning cloud cover than what was actually received that day (and/or higher temps than what actually occurred), but matches the system output in the afternoon very well.

Now let's use the same method as J.P.M. suggests, and compare the output for the year with and without clipping:

PVWatts (no clipping): 14608 kWh
Live system: 14429 kWh
Difference = 179 kWh

If we replicate that model on the system being discussed:

7.7 kW (capped at 225*28 = 6300 W)
92128
240 deg azimuth
18.5 deg tilt
"premium"
roof mount
6% loss

PWatts (no clipping) = 13771 kWh
Projected (with clipping) = 13724 kWh
Difference = 47 kWH

At 0.20 / kWh, that is worth about $9.40 / annually.

If you want to use TOU pricing with $0.49 / kWh from 12 pm to 6 pm, it is more like $23 annually.

I just don't see the financial justification for spending $500 for what is certainly worth less than $50 annually in cost avoided. However, as I think some forum members have shown, there is an emotional component to the decision for many people. "Loss Aversion" is influential in decision making, and many people look at the flat top of a clipped day and freak out, even when accepting that clipping was the better financial decision. For those people, spending the extra $500 might be worth the peace of mind, even if some of us only see money spent for no tangible return.

Thanks for the great run through. It really puts a point on it.
Funny how you can still be drawn to doing the 250's emotionally even when you see the math.

[J.P.M.]

If you believe people who vote with their money know what they're doing.

FWIW: People may vote with their money, but that may well say less about their ability to make intelligent choices as informed voters than it does their penchant to usually avoid the longer view if favor of a penny wise, pound foolish and short term, simplistic outlook.

[thejq]

While we are making up stories about what might cause a microinverter to fail, I would question why Enphase hasn't released a 275W inverter (or higher), despite the willingness of a customer base to pay for it (even if it won't yield much more energy than the M250 in most installations). Perhaps they've found in testing that even the M250 is at (or slightly beyond) their limit of reliability, and that really the M215 is their most robust design on the market. This would explain why they continue to recommend the M215 for 270 W panels, a recommendation that is counter to Bruce's suggestion that operating at rated output will hurt its life. If the M250 were really more reliable for panels 225 W and above, I would think they would want to limit their warranty exposure and be pushing the M250's in those applications.

M215 paired with 270W panel will most certainly be less reliable than M250 + 270W. There're many reasons to have multiple products on the market, even if one is superior -- unit cost, profit margin, replacement cost, BOM, existing tooling and product mix, just to name a few. What costs less to produce also requires less to warranty even at higher rate of failure (remember now they don't cover labor cost for replacement). As you pointed out, I'm too very concerned about Enphase not able to design a higher wattage microinverter after the M250 (released in 2013). While I favor SolarEdge from a technical POV, having competing technologies in the market is always good for consumers. If you believe people who vote with their money know what they're doing, SEDG is now worth almost 4x the capitalization of ENPH (up from 3x just a month ago). I sincerely hope Enphase can come up with something more compelling and quickly. After-all, they practically pioneered the individual tracking concept, very much like RIMM invented the smart phone before AAPL buried them alive.

[J.P.M.]

Good point.

I also wonder due to the number of new manufacturers getting in on the microinverter market if Enphase is working on a brand new design but wants to sell off built up inventory of all existing versions.

And perhaps something to do with mgmt.'s view of what's in the co.'s best interests both long/short term, although I'd not place a very high probability on too many American co.'s mgmt. thinking more than about 3 months ahead.

[SunEagle]

While we are making up stories about what might cause a microinverter to fail, I would question why Enphase hasn't released a 275W inverter (or higher), despite the willingness of a customer base to pay for it (even if it won't yield much more energy than the M250 in most installations). Perhaps they've found in testing that even the M250 is at (or slightly beyond) their limit of reliability, and that really the M215 is their most robust design on the market. This would explain why they continue to recommend the M215 for 270 W panels, a recommendation that is counter to Bruce's suggestion that operating at rated output will hurt its life. If the M250 were really more reliable for panels 225 W and above, I would think they would want to limit their warranty exposure and be pushing the M250's in those applications.

Good point.

I also wonder due to the number of new manufacturers getting in on the microinverter market if Enphase is working on a brand new design but wants to sell off built up inventory of all existing versions.

[sensij]

While we are making up stories about what might cause a microinverter to fail, I would question why Enphase hasn't released a 275W inverter (or higher), despite the willingness of a customer base to pay for it (even if it won't yield much more energy than the M250 in most installations). Perhaps they've found in testing that even the M250 is at (or slightly beyond) their limit of reliability, and that really the M215 is their most robust design on the market. This would explain why they continue to recommend the M215 for 270 W panels, a recommendation that is counter to Bruce's suggestion that operating at rated output will hurt its life. If the M250 were really more reliable for panels 225 W and above, I would think they would want to limit their warranty exposure and be pushing the M250's in those applications.