I agree that all three and more effects you note can conspire to synergistically increase output to beyond 100% STC output, or more to the point, cause noticeable and perhaps measurable changes in output (as, FWIW, I've measured on more than a few occasions), but the other effects you note besides albedo that are cloud irradiance need not be present and, more to the point, even when present, are usually of a minor nature when influencing array or cell output and ultimately, even when present, are either already smaller than the irradiance forcing function or so slow in their effect relative to the panel thermal time constant as to be immaterial to "changes" in output. For example, if we agree that an albedo caused increase in array output is often and usually noticeable by virtue of the relatively abrupt, sharp and short increase (or decrease if/when abrupt shading occurs) it causes in array output, as well as it's relatively short duration, and since a panel's thermal time constant is of the order of several to 10 minutes or so and somewhat variable depending on environmental conditions, that would make the effects by the other variables on the array output through the effects on array temp. much less noticeable as f(time) with respect to array output.
The primary cause of temporary spikes (up or down) in an array's output, and the time rate of change of that output is changes in the irradiance level, with that cloud albedo effect being nearly instantaneous. The other effects you write of are of much less importance, or may not need be present at all. Even when present, and by some SWAG reckoning on my part, and mostly anecdotally, those other effects seem to be maybe something like about an order of magnitude less of an influence on array output than changes caused by temporary increase in array input from cloud albedo, particularly when the effects that the thermal hysteresis/panel thermal time constant can have on the cell temps. are considered.
The other environmentally caused effects on array output through effects on array temp. you write of will change the array output by causing changes in the cell temperature. Because of thermal hysteresis, those environmentally caused changes in temperature will, for the most part, lag behind any noticeable changes in output caused by increased irradiance, and as a point of my observation and experience, may well not have any effect on output until such time as all or mostly all temporary albedo caused increase in output has run its course with the result that the time rate of decrease in output on the back end of an albedo spike may well be longer or less "spikey" than the rise time.
As for the cleanliness effects of rain, I strongly agree that a good rain can remove dirt. By some measurements I've done over the last 4+ years, I'd est. that a good rain can restore ~ ~ 2/3 - 3/4 of an array's output that's been lost to fouling, but that'll still only be a, say, maybe 2-4 % increase in output on average, and furthermore, without some pretty tight before/after measurements, be tough to quantify, and at any rate, sure not the 10+ % or so increase we seem to be 're talking about here.
To reiterate, to my measurement, learning and experience, the primary and overwhelming cause of temporary increases in array output are temporary increases in temporary irradiance on the array when caused by temporary increases in albedo, usually from clouds. Other environmental effects may or may not be present. Either or any way, those environmental effects which mostly effect array output through changes in array temp. are small contributors to observable and temporary increases in array output.
Respectfully,
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Agreed. But the combination of all three is what might just push panel output to over 90% of STC. Or even over; I've observed over 100% of STC for a short time during the above-mentioned clean/cool panel and cloud lensing event. (Or "cloud scattering effect" if you like.) It dropped back under 100% pretty quickly as the panels warmed up.
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The sun is not magnified by the clouds. The effective solar irradiance (some suggest that's a redundant term) on a surface or array can be increased by albedo from objects and/or conditions that may be terrestrial (ground based surroundings), or in the atmosphere (usually clouds), or extraterrestrial (usually the moon and usually effectively == zero). "Cloud albedo" or "cloud reflection" may be a better, more accurate, or at least less misleading or confusing term. The terms "lensing" or "cloud lens" or "cloud lens events" can be a bit misleading as a lens is usually used for the intentional redirecting light (or maybe sound). Clouds do not. Nor do they magnify the sun. They may simply and randomly reflect, mostly in a forward scattering manner, light from the sun, just like terrestrial albedo, except terrestrial albedo is not called "ground lensing".
Also, temporary albedo caused increases in PV device output do not need clean(er) panels, nor do albedo caused increases need cooler panels to be noticeable. The effect on PV output from cloud albedo or reflection can be quite noticeable on clear, dry weather under skies that are partly cloudy with scattered cumulus clouds.Leave a comment:
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I can't speak to the aesthetics, since it can be hard to make it look seamless unless everything (panels, racking) is exactly identical.
But in terms of output it will look very similar. About the only time you will see a difference is during the rare "cloud lens" events, where:
1) It rains enough to wash off the panels
2) It rains enough to cool down the panels
3) The sun comes out through a hole in thin clouds.
At that point the panels are clean and cool (their most efficient state) and the sun is magnified by the clouds (you are getting direct sun plus diffused sun from the clouds.) At that point you might see 10% more power from the new panels. But other than cases like that, the output will look the same (new vs old.)
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So to be clear, if i stay with 215 or 250 on my added panels, my array will be one and just look like it grew?
They mentioned using similar panels to what I have (maybe the Phonos are not available) but not add them to the end of my array on roof but separate them a bit.... so unsure yet how that impacts wiring, etc.Leave a comment:
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Thanks for the advice. I figured the 215 seems to be doing ok, so why change. Will talk to vendor to find out if I can stay with 215s with the extra 6 panels or 250s (if compatible). I assume you mean by a 'single array" is that they use the same net-meter and I only have to monitor (via network) 1 system. That would be convenient.
Seems the laws in CT have changed and net metering is going away.... but I am grandfathered in, and this may be a good time to add on since i barely make enough to cover my year usage anyway (we are frugal and a bigger family in the future who may use the a/c and dryer more will need a bigger system...
I am also on oil (water baseboard) heat and the solar guy recommended i look into a heat pump (my a/c is original from 1988). I need to run some numbers to determine if the costs and savings will balance out over time (how long?) - it would be nice to get off (or significantly reduce oil) as those prices also seem to rise.
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Thank you for what I believe is intelligent comment rather than the usual childish pap from snowflakes with misplaced, hurt feelings and childish, entitled attitudes that come out every time they read something that offends their delicate, overinflated egos.
I believe we agree to disagree on this one, but otherwise seem to be mostly on the same page.
With pre-apologies for breaking my last word commitment: My logic may appear to be circular only if the last sentence of your first paragraph is valid as it may relate to influencing a buyer's decisions. But I have a different view from the last sentence of your first paragraph: The customer drives the purchasing. The seller tries to shape the opinion of the buyer and so control which way the customer's opinion is driven, hopefully taking that opinion in such direction that it goes in the seller's favor using tools the potential buyer is completely and utterly unaware of. 10+ years in a prior existence as a peddler taught me that. My opinion only: What looks to me like your almost exclusive public endorsement of SolarEdge equipment still leaves me scratching my head. Maybe it's my attitude, and maybe I'm wrong, but after being on this planet for a long time, I've found if I think cynically, I've rarely been disappointed, with a bonus that when I've been wrong, I've been pleasantly surprised. I like to be pleasantly surprised but I can't see how that will happen this time.
On panel level monitoring : I do believe panel level monitoring can be useful to flag problems and can be a useful tool for system analysis. Truth to tell, I wish I had that capability but get by without it. But my guess is (and this is a comment on the result, not a criticism of any user choices), that's a system capability and information that may have more overall benefit to sellers for marketing hype than to most users who mostly neither know or care about system monitoring. Even if understood, my experience (and maybe/probably some educated guess) is that panel level monitoring is mostly a system feature ignored most of the time, or entirely. One upshot from that: The way I see and read about and suspect most users don't look at their array monitoring any more than they look (for example) at their water heater, and so, when a string inverter fails, probably/perhaps involving the entire system, that failure will probably produce a big result and that big result will get attention quicker and get a lot more notice than and perhaps a smaller panel failure which might go unnoticed more easily.
Now I am done.Leave a comment:
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remember though we do buyer brokering. and I (me personally) evaluate the technology and choose the best equipment to use. I do it based on technology and cost performance.
We install enphase as well and I personally view them as the best of the micros but sub to SolarEdge and some string systems like SMA.
We are NOT the installer, though we contract with them and give them the design that was work out with the customer.
I also use mac computers and have for many years, I am a unix guy and have been in the IT area for decades, so macs are a comfortable and technological fit. I also have done cost analysis on them and they tend to last longer and take much less IT time. Do I have a relationship with Apple because I use and recommend Mac computers? no I use and recommend them because in my opinion they are better for several reasons. By your logic (which is a bit circular) because I recommend and thus companies I have worked for have purchased a lot of Apple computers, I have a relationship with them. but that is now the case. The opinion drives the purchasing, not the other way around.
It is the same with SolarEdge, I feel it is superior and that monitoring is important particularly given our model of being a customer advocate that looks out (and monitors) the systems for the customer. We set up monitoring on other systems but it obviously is not up to snuff of SolarEdge monitoring.
and on Sunpower no I have not and I tend to agree with you on them. I only wanted to fully disclose that I have some, I actually worked for Lockheed Martin and about 1/3 (largest single section) of my investing is with them. It does well so I keep it. My solarEdge stock is the same way, when I deam it will not do well I will sell.
It really is my opinion that SolarEdge is a damn good system and on top of that easy and pretty safe for a DIY type install because of many of the safety features. I also prefer OutBack (and personally own one) for Bimodal systems, I know others like Schneider. My boss has one and I have had a lot of dealings with it, installed right about the same time as mine. His is crap and constantly having problems so my opinion of OutBack is likely to stick for a while. All of the bimodal and off grid installs we have done, except for the more recent StorEdge systems have been OutBack and my opinion has continued through with monitoring them.
We have done some Fronius installs and had poor luck with them. One install had two inverters and one was replaced twice, the other once. That was 3 or 4 years ago I think. We have primarily done SMA for string since that time but SolarEdge is the default inverter. We have done quite a few enphase, some for customers just wanted them and others because the system was too small or no good place to actually place an inverter.
I hope this helps clear up my opinion. I know I have stated several reasons on different threads of why have this opinion of SolarEdge, so no need to rehash that.
You and I just disagree on the general idea of simplicity of string in non shade situation over benefits of monitoring. I see your point and agree a string inverter has less points of failure and true a mildly technical person will see a failure. I am technical but years in IT has shown me that even technical people in one field are not the most adept at noticing tech problems in another field (computers or solar). I am not arguing that someone couldn't see it but that a lot of our customers and corollary a lot of general populous WOULDNT notice a problem. Hell riding in other peoples cars it is surprising how many don't knowtice basic problems with their own cars but this day and age there are so many people that have no idea how a car works much less what is a problem. My point is just that many people are pretty oblivious so a system that solaredge monitoring that can send alerts or have a third party checking is of benefit and in my opinion outways the benefit of reduced points of failure, also given the low failure rates we have seen. I also think it is good for people to see your opinion and mine and understand where we are both coming from so they hopefully can fit it into their own view for their install, on a tech board like this.
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Before I respond to your main points, I do think that string inverters are a better choice for many, maybe even most, but not every residential PV application, at least in most of the U.S. But that's an engineering/ design choice, and not one suitable for every application, just like I think it's better in most residential applications to put the inverter in the garage or at least out of the elements as a preferred location, or that nat. gas fired heating systems are generally better than coal fired for most residential applications. Those are design considerations not brand preferences. I've got a rebadged Power One inverter in my garage that has additional and fit for purpose air cooling.
To your point about Fronius: Some of their design philosophy is better than some other of their design philosophy. Some engineers like SMA. There is no perfect piece of equipment. As a general equipment design philosophy, for me, and as a retired M.E., from an design and engineering standpoint, among a lot of criteria, simpler designs with thus fewer failure points are a better way to start and probably finish for me. So is common sense. Keeping the number of inverter heat and environmentally sensitive components as low as possible and keeping them out of harsh conditions (like on a roof) as much as possible, particularly where there will be little to no inspection/maintenance seems like common sense bordering on a no brainer. That's a lot of why I generally favor string inverters in principle. Micro inverters or optimizers do not fit what are to me, common sense requirements for most applications, and therefore, if I was designing residential PV systems, probably not making them my usual first choice. One exception being shade. But even there, if a location has shading to the point it needs micros or optimizers, I'd look long and hard as to whether that's a good application to begin with. Reason, and dirty little fact hiding in plain sight: Micros will not generate sunlight where none exists in the first place. The "I have shade so I'll get micros and solve the problem" is a common refrain that vendors do nothing to qualify. Micros, or optimizers will not restore insolation (BTW Butch - it's insolation, not insulation as you consistently seem to misuse/misspell) that's been lost to shade. If an application is, say, 30 % shaded, micros will not restore that lost 30 % - maybe half of that 30 % or so. So, you wind up with some recovery for what's a crappy application to begin with. Better than nothing, but my guess is less than potential users are left to imply on their own from the product literature. It's still a crappy application.
As for business relationships and how you define yours, it looks like we have different ideas of what a business relationship is. If you work for or own a company that installs and services SolarEdge equipment, and by your words, a lot of it, to me, that bears all the hallmarks of having a relationship with SolarEdge. Do you see where that could be interpreted by more than a few as having a business relationship with them ? If so, and acknowledging without question your undeniable right to opinions, by what looks to me at least to be your usual and strong defense of their systems and again, to me anyway, you often look like an apologist for what others see as failures and shortcomings of SolarEdge equipment and/or usually have an overly eager suggestion that SolarEdge has just the cure for a stated situation to the exclusion of just about everything else. To me at least and maybe I'm the only one, but you look to me to be one of their most persistent apologists.
Sometimes, probably often, perception, accurate or not, is everything.
Butch, this obviously isn't my forum to run, and not my call, but it is a place to exchange information and opinions. To me anyway, and maybe I'm the only one, it looks like you're using this forum to peddle a SolarEdge bill of goods.
As for investments, I once owned a boatload of Sunpower stock. I also own a Sunpower system that the stock appreciation paid for 10+ times over. You may have noticed that didn't ever and hasn't yet stopped me from calling B.S on their sales hype and preaching the "Sunpower is good stuff but not worth the premium" mantra.
The last word on this is yours.
Respectfully,Leave a comment:
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I have no relationship to solaredge. In my opinion ghey have a superior product and we have installed a lot of them though not exclusivly.
Just like you and others prefer string inverters and i think you like fronius string inverters in particular.( could be wrong on brand).
I do have a small porton of my investing in solaredge ( less than 5% as i am very diverse).Leave a comment:
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Depending on shading, and cost, it might be worth considering the idea to scrap the micros all together and replace them with a string inverter that has multiple MPP tracking. Just sayin' that as long as a major inverter expense is being considered like changing out working micros anyway, it's a viable option that gets away from micros altogheter - again, as long as major shading is not involved. If the shading is that significant, it's a poor application anyway, so leave it like it is and don't throw good money after bad.Leave a comment:
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So just what is your relationship with SolarEdge ? Any ? None ?
If you have no professional, employment, consultational, financial or any other type of relationship with SolarEdge, please accept my apologies for my assumptive error.
Seems like you pitch their paqrty line and mantra of goodies about as much or more than I pitch "Solar Power Your Home for Dummies".Leave a comment:
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Actually a totaly different option would be to install m250 micros on the new modules which would allow expansion of the single array in monitoring and would deffinitly be cheaper. There might be some clipping on the new pv modules depending in the their capacity but that could be a minor issue. I would personally lean this way were this my customer. ( leave the M215s and add M250s)Leave a comment:
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Good points. I also don't like that he threw efficiency into the equation because the M215s are pretty efficient as it is.
Desmo, here's an opinion from a user, not a professional, so take it for what it's worth. Of the 46 M215s I and a couple of friends purchased 4-6 years ago, none have failed, so I have a good feeling about the reliability of the M215. One of those systems was an expansion on a house with an existing system using a string inverter, and there was no issue with the two different systems feeding the same service panel, so I don't see a compelling reason to replace the M215s unless you don't want to have two separate systems to monitor. That's a valid point, but if I was doing this I'd look into adding more panels with M215s, if still available with warranty, and throw in a couple of spares. The advantages would be not switching from (apparently) reliable units to less-proven units, and using the existing Envoy for monitoring. But even with a mix of new vs. old, I wouldn't mind, I almost never monitor my system anymore and it wouldn't bother me having two systems to look at instead of one to occasionally check the system.Leave a comment:
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