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I had a solar edge system installed fall of 2017, operational end of October. The number of panels = 6.960 kW but when I monitor the system performance I noted the output clips at 5.0 kW When I asked my installer he said that the seemly small size of my interver is IAW the recommendations of the manufacture. It would seem that due to the size of the inverter I am limiting the amount of power realized to almost 2 kW less that what the panels are capable of producing. Need some guidance to the proper size selection of the inverter for my system
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Your installer is living to you. SolarEdge does not recommend a side of inverter. They have limits to the amount of dc that can me installled on a 5kw inverter and the installer chose to hit that limit. You would likely almost never hit 6.96kw production with a larger inverter but would hit something higher than 5kw if you are flat lining.
It sometimes makes since to limit that much if say you say you had a lot of shadows, or solar on east and west, or your electric for some reason or other limited you to only a 5kw inverter. But SolarEdge does not recommend the size of the inverter other than setting the limit.OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH -
I was almost put in the same situation as the OP. I signed for an agreement for 21 Panasonic 315W panels (6.615kW total) and based on recommendations from this forum and my own runs of PVWatts and the SolarEdge Site Designer tool, I decided to request the SE6000H inverter, when the installer had originally recommended the SE5000H. This is in sunny So Cal, and my roof is exactly South facing, with minimal shade issues. Various company reps that had done site evals had mentioned that my roof was just about ideal for PV panels.
Panel and inverter install was yesterday, and lo and behold the team brought a SE5000H inverter. When I mentioned that we were supposed to have the 6kW model, the foreman showed me the plans showing the 5kW. Calls to the company were made wherein I got quite a bit of back and forth trying to convince me that the SE5000H was what SolarEdge recommended for my size array, with some fuzzy math to try to show that I would not lose anything using the 5kW inverter. When I mentioned that the numbers that I had run suggested I would experience quite a bit of clipping with a 5kW inverter, I was even told, "I've never heard of clipping before." Needless to say, I was transferred to one of the senior owners of the company.
In the end, the owner agreed to switch with the SE6000H inverter, esp. since that was what was written in the signed contract. But the 5kW inverter was already installed and we powered the system up today while waiting to get the 6kW inverter swapped. And I was able to see first hand that requesting the larger inverter was the right call, as from the moment that the system was powered up around 11:45AM the production hit the 5kW inverter ceiling and remained pegged there until 3:30PM when the system was shut down and the 5kW inverter was swapped with the 6kW. I'm pretty sure that the system would have been clipping for some time before 11:45AM. This was a clear day, with close to 90 degree temperatures, and with the lower temperatures that are more typical this time of year I'm sure that there would have been up to 5 hours of clipping, if not more.
JPKHole19, what is your location? And are you able to share the monitoring charts showing the degree of clipping that you are experiencing.Comment
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Kendalf: I'd be interested to see what your system's power levels and daylong output were after the swapout.
In zip 92026 the two days were similar in terms of irradiance with some minor clouds in the A.M. on the 10th and cloudless all day on the 11th, but cooler.
FWIW, after shading adjustment, my daylong production on the 10th was ~6.24 kWh/S.T.C. kW, and ~ 6.44 kWh/S.T.C. kW on the 11th, with the 11th being about 5 deg. C. cooler on the roof during daylight hrs. and also, besides no morning clouds, a bit sunnier daylong with less water vapor in the air. Daylong clearness index on the 10th was ~ 0.69, on the 11th it was ~ 0.70.Last edited by J.P.M.; 04-12-2018, 11:47 AM.Comment
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Most contractors will do whatever they think it takes to win a bid, especially if you allow them to design and select the specifications.MSEE, PEComment
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I would say that a lot of installation companies, big or small, push the limits of what they can get away with on inverter size. Foolishly I say. Larger inverters cost just a little more and we take the opposite thinking in advising customers to oversize their inverter so that they have room for growth and better reliability. Adding on more panels to an oversized inverter is a easy. Switching too a larger inverter is almost never cost effective.
Yes, PV arrays rarely generate what the label rating says, but going more than 10% over is not really smart.BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installedComment
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Looks like it may take a bit more time to get Solaredge monitoring working, so I don't know what the peak production level was today. I've completed the registration but everything is reading 0 in the dashboard. I'm wondering if they may have configured it with the serial # of the 5kW inverter.
What irks me is that I had discussed this with their system designer earlier and the agreement that we signed stated the SE6000H inverter. The switch to the 5kW inverter was made without my knowledge or agreement.
The thing is, I noticed that the 5kW inverter that the installer had originally mounted was the model with the revenue grade meter, and the actual cost of that model is actually more expensive than the 6kW inverter w/o the RGM. I agree with you that it doesn't seem to make sense to put too small an inverter in because of the relatively minor cost difference, and SolarEdge even states that companies may want to reduce their # of SKUs and just standardize on their 7600H line as it can account for a wide range of PV arrays. One possibility is that many companies have an oversupply of the smaller inverters but the average residential PV system size seems to be going up so they are trying to get rid of their smaller inverters as fast as possible.
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That is breech of contract and you have a legal leg to stand on. Threaten legal action. Or even better pay a lawyer to write them a letter threatening legal action if you do not mind paying for an hour or two of his time. Smear their name on Facebook, harass them, embarrass them publicly, make false allegations if they do not respond. Today all you have to do is make an allegation to be considered guilty.Last edited by Sunking; 04-12-2018, 08:34 PM.MSEE, PEComment
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Oh they already switched with a 6kW inverter, so no need to go down that route now. I do plan on making some comments about this if I post a public review of the company, considering that I would have been shortchanged if I hadn't noticed the downgraded inverter during the install.Comment
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SolarEdge data went live for my system at 10:30AM this morning, and I could immediately see the benefit of maintaining my request for the 6kW inverter. First production data point was 5.365kW, and the system hit the 6kW inverter max at about 11:30AM and stayed there until about 1:45PM. Looking at the production curve, I probably would have been clipping on the 5kW inverter from a little after 10AM to 3PM. Temperature was in the mid-80s in the afternoon, pretty much clear skies all day. Looking forward to seeing my first full day of production data tomorrow!
Using the SolarEdge "playback" feature showed peak PV array production was just about 6,200W at 1PM. JPM, I'm not sure how to calculate the kWh/S.T.C. kW figures that you described.
SolarEdge Day 1.PNGComment
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The flat top of the production curve usually means clipping is going, but given that this is about the most productive time of the year and therefore the rest of the year will have less potential production, I'd bet you won't be losing much to clipping.
S.T.C. daily kWh production per S.T.C. kW == daily system output/system size in S.T.C. kW. For you, if the reported daily production # is accurate 04/13/2018: Daylong production = 36.85 kWh. System size = 315W/panel * 21 panels = 6.615 S.T.C. kW. --->>> 36.85 kWh per day/6.615 S.T.C kW = 5.57 kWh per day per S.T.C. kW. By way of comparison only, my output was 6.50 kWh/S.T.C. kW.
If I were you, I'd wait for some clear days and full reporting before I pass any judgement. FWIW, and by way of very loose comparison, my production rate @ 1345 hrs. today - about when your clipping seems to have stopped - was ~4.4 kW or ~ 84 % of S.T.C. output for my system with a fouling penalty of ~ 1.7 % as measured at 1309 hrs. P.D.T. Your output at ~ 1345 hrs. looked like about 6.0/6.6 or ~ 0.91 or so on what may be similar fouling to mine. That's pretty high output. I'd compare a few more days before I passed judgement. From that 0.91, it looks to me that your roof ambient air temp. was REAL cold today (like ~ 50 F. or so) , or the monitoring is optimistic on output.
Now, let's get out of JPKHole19's thread. Bad etiquette and apologies to the OP.Comment
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J.P.M. Had the first full day of logged solar production and I'm pretty happy with the results. Curve is pretty much congruent with the partial data from yesterday. Total system production according to SolarEdge monitoring was 47.15 kWh, so that seems to calculate out to a 7.12 kWh/STC kW (47.15kWh / 6.615kW STC system size). Temperature hit a high of about 85 F like yesterday, but less wind than yesterday. I know that production will go down as temperatures increase and as the panels degrade, but it's nice to see the system performing even better than I would have expected.
SolarEdge Day 2.PNGComment
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System performance looks about what I'd expect. You still have some clipping (the flat top), with ~ same max. output as yesterday, but probably not much loss in daily production at what's about the most productive time of the year. I'd live with it.
Now, can we get out of JPKHole19's thread ?Comment
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