Comments on 7.2kw system in San Diego

[silversaver]

Same size system with Enphase microinverters at different orientation with different result:

https://enlighten.enphaseenergy.com/pv/public_systems/KWpC417458#null/production/graph/days

Now, is the Solaredge monitoring offering correct output result?

[J.P.M.]

With regard to the daily energy reported by solaredge inverters, I've been collecting evidence that they systemically inflate the total by about 3%. On clear days, a more accurate total can be generated by summing the reported 15 min power readings. More to come.

I've got a sneaking suspicion that most inverters (string anyway) overestimate array output by something like that amount but I don't have #'s to back it up yet. I suspect mine (rebadged PowerOne) reports high by something like that amount.

[ericf1]

With regard to the daily energy reported by solaredge inverters, I've been collecting evidence that they systemically inflate the total by about 3%. On clear days, a more accurate total can be generated by summing the reported 15 min power readings. More to come.

I'm seeing the same 3% difference between what the inverter reports and 15 minute averaging by PVOutput over the 4 day period I have that data (159kwh vs 154kwh).

Using a single day as an example, I summed all of the 15 min power readings for the day and multiplied by .25. This gave me the exact same result as PVOutput. I'm not sure what SE is doing to arrive at their figure.

[silversaver]

I've got a sneaking suspicion that most inverters (string anyway) overestimate array output by something like that amount but I don't have #'s to back it up yet. I suspect mine (rebadged PowerOne) reports high by something like that amount.

I don't think is the inverter itself. Inverter actually report at actual output without any loss or power consume by inverter itself. It is the monitoring system.

For those who have solaredge system, at end of the day, check both reading from inverter and monitoring software.

[thejq]

I don't think is the inverter itself. Inverter actually report at actual output without any loss or power consume by inverter itself. It is the monitoring system.

For those who have solaredge system, at end of the day, check both reading from inverter and monitoring software.

The inverter output at the end of the day is exactly the same as the monitoring sw. But if you take the 15-min reported wattages, sum and divide by 4 you get a slightly less number eg 3%. Without any proof I am guessing it has something to do with transmission loss or how the 15 min wattage is reported. If you look at the lcd on the inverter the wattage changes instantaneously. Somehow an average has to be calculated and reported.

[sensij]

The inverter output at the end of the day is exactly the same as the monitoring sw. But if you take the 15-min reported wattages, sum and divide by 4 you get a slightly less number eg 3%. Without any proof I am guessing it has something to do with transmission loss or how the 15 min wattage is reported. If you look at the lcd on the inverter the wattage changes instantaneously. Somehow an average has to be calculated and reported.

Agreed, it is not the monitoring software, but the multiple ways that the inverter does calculations that leads to the discrepancy. I've been working with SolarEdge support on this, and they have not dismissed my observations as lightly as some forum members have. The discrepancy is not simply due to averaging, and there are a couple ways that this can be proved, which I intend to present once I have the whole process more clearly understood. My recommendation is to trust the power readings, and sum the power to get energy, and have less faith in the direct energy readings, but until I can prove why, skepticism is welcome and warranted.

[J.P.M.]

I don't think is the inverter itself. Inverter actually report at actual output without any loss or power consume by inverter itself. It is the monitoring system.

For those who have solaredge system, at end of the day, check both reading from inverter and monitoring software.

I'd agree with the monitor reporter as the (possible) culprit. That's what I was trying to say, I think. Fingers faster than brain. My bad.

[DanS26]

Guys, if you want accuracy you need a utility grade meter. Those inverter readings are just plain crap.

Two ways of going about accurate readings....get a utility meter and install in line or get a utility grade CT system installed in your distribution panel.

This company has all the right equipment at the right price...contact them.

http://www.hialeahmeter.com/

[ericf1]

I Finally received my first full month bill from SDG&E since powering up the system. We had plenty of sun, but it stayed cool enough to minimize running the AC. Net usage was -603kwh. My system was off during all but the last 5 days of my first month of net metering, so I came into this month with 440kwh used, so now I'm at -163kwh. On my best day, I generated 50kwh and had a net use of -33.635kwh. Looks like I should be able to generate plenty of credit to run the AC as much as I want this summer.

bill.jpgDaily energy use.jpgbest day.jpg

[Alisobob]

cool.JPG

I'm right there with ya'!!

[Cyang]

Name of your company

After talking to six installers, I'm settling in on a proposal/bid for a 7.2kw system inland from San Diego (92071). The plan includes 24 LG300N1C-G3 panels, a Solar Edge SE7600 inverter and P300 Power Optimizers on my south facing, 18 deg roof. My current annual usage is about 12,600 kwh, so this system should cover my usage. I guess I could save a few bucks going with the SE6000 inverter, but I like the idea of having room for growth without replacing the inverter.

I like the monitoring of the Solar Edge system, and don't mind spending a little extra for it, but my roof will see very little shading. Am I throwing money away with this system, or making it unnecessarily complex? My impression so far is that Solar Edge equipment is pretty solid, but they have not been in the US long enough to establish long term reliability. I also received a quote using Sunpower 245 panels, but just can't see the 25% premium paying off.

Appreciate any comments or recommendations!

Eric

Ericf1

Could you PM me your company name you went with?

Calvin

[ericf1]

Ericf1

Could you PM me your company name you went with?

Calvin

Sure, PM on the way.

[ericf1]

Well, February was my "true-up" month. There were a few issues with start-up and SDG&E, so things are off a bit. First, my system was off for the first 25 days of NEM billing, so I consumed 440 kwh for my first month. Then, they debited my bank account for this 440 kwh. With the incomplete month and billing error, the numbers don't tell the whole story. What they do tell me is I'm over producing. A lot.

Even with less than a full year, and 440 kwh consumption prior to system turn on, I over produced by 2,329 kwh.

I thought I would be a lot closer to zero, and was even generous with the AC once I saw the credit pile building up. Maybe it was the mild and sunny weather, or conservation efforts, or both, but my consumption is down and production is exceeding estimates. I have had excess production every month except the first partial month. Worst month was October at -2 kwh, best was April at -603 kwh.

3 weeks short of a full year, I'm at 12.9 mwh total production per SE Portal.

[J.P.M.]

Well, February was my "true-up" month. There were a few issues with start-up and SDG&E, so things are off a bit. First, my system was off for the first 25 days of NEM billing, so I consumed 440 kwh for my first month. Then, they debited my bank account for this 440 kwh. With the incomplete month and billing error, the numbers don't tell the whole story. What they do tell me is I'm over producing. A lot.

Even with less than a full year, and 440 kwh consumption prior to system turn on, I over produced by 2,329 kwh.

I thought I would be a lot closer to zero, and was even generous with the AC once I saw the credit pile building up. Maybe it was the mild and sunny weather, or conservation efforts, or both, but my consumption is down and production is exceeding estimates. I have had excess production every month except the first partial month. Worst month was October at -2 kwh, best was April at -603 kwh.

3 weeks short of a full year, I'm at 12.9 mwh total production per SE Portal.

As suggested by prior posts to your threads, that production was somewhat predicted and mostly in line with the suggestion that LG and Sunpower systems will produce about equal annual output around here of about 1,700 kWh/yr per installed kW or so for unshaded south facing @ ~ 20 deg. tilt. I suspect you're getting a couple % or so boost in production from reflection off the patio roof.

To the degree that vendor supplied monitoring is the be believed, looks like you're at ~ 12,900/7.2 ~ 1,792 kWh/kW.

As a loose comparison, my stuff put out ~ 1,745 kWh/kW for the prior 365 days using S.P. 327's @ 195 az., 18.75 deg. tilt.

Looking through your older posts, I couldn't find your installed price/Watt for the LG's. Care to share it ? When you purchased/installed, the best S.,P. price around was ~ $4.50/Watt.

[sensij]

FWIW, the discussion earlier in the thread about overstated production numbers by SolarEdge has been proven with revenue grade monitoring. When looking at their energy report, it is likely to be 3-4% overstated. The power report is better, usually agrees within 1% on clear days, although it drifts a bit throughout the day.

ericf1, nice to see your first year in the books! Because your system came online within two months of mine, I've found it to be a decent reference system for my own array. Some insight into fouling / degradation may come from the relative performance of our arrays as I get my past my 1 year mark as well, 6 weeks from now. Since then I've added an irradiance sensor to my roof to help calibrate the models, but I've got some work to do (and some questions to answer that have been asked in other threads) before I can report much against that.

The lower consumption is sort of interesting. Conventional wisdom is that people increase their consumption with an array, because, free power. I think there is a segment of the population that actually becomes more efficient, because their electrical awareness is substantially higher if time was taken during the PV planning to understand more about how residential energy works. If you are really interested, you can download your net consumption history from SDG&E from the past two years and combine it with your SolarEdge data to see your true consumption, and determine in what months the reduction occurred (testing the "mild summer" hypothesis).