ESBN New Regulations on NC6 Form on 6kW 25amp Inverters May 31/2023

See anything wrong with my math? Yeah, I did. Did you?

"but full sunshine at 9am isn't the same as full sunshine at 1pm on a south facing panel. Your not getting clipped at 9am are you? Even though Ireland might be in "full sunshine" so to speak. So the monies, I think, are a lot less than that."

That's why I've the 60% utilization factor on South facing panels. The math is right. BTW, mine are south facing, I get 6kW by 10:30 at this time of the year.

These lifers are trying to keep themselves in the cushy number, and spout this nonsense to the clueless politicians, who of course couldn't care less anyway because they get their big dividend every year, the more the people pay, and the less they get paid, that more kickbacks to the government.

Look back about 15-20 years in the German market. Home owners were making a small fortune. Suppliers didn't like that....

Well the smart meter would give them your export profile, and would show 7kW if you ever exported that much.

Yes, currently that's the only way they would know, unless they had access to your inverter data, which they shouldn't have. They wouldn't really care, because without a smart meter you won't get paid for the 7kW anyway, you get a guesstimate.

Still not seeing the math. We may have to "agree to disagree" here :-)

Your saying your being clipped at 10:30am (and I believe you), but at 10:30am your not being clipped the full amount at that time (i.e. the difference in total Kwp to your inverter size). What I mean by that is you might have 6.5Kwp available but clipped to 6.4Kw, meaning your only losing that 100w at that time out of 6.5Kw you could potentially get.

10 mins later that will probably rise on the sine wave curve to 6.6Kw available but again your being clipped to 6.4kw. Really there's only 1-2 hours either side of solar noon where your actually being severely clipped from your theoretical max of 8Kw. And at that worst case it's like 1.6Kw out of the 8Kw (assuming you could get all 8Kw)

The hours of sunshine doesn't take into consideration any angle of incidence to the panel. A bight full hour of sunshine in Winter isn't the same as full hour of sunshine in May with the slant angles, so using the hours of sunshine that way doesn't take slant angels into consideration. Panel temp also makes a difference too. August has more hours of sunshine than April but typically we produce more in April as the panels are cooler, so you'll be less likely to experience clipping.

All told while bigger inverters help reduce clipping and I personally would perfere a bigger inverter myself, the effect isn't as much as you would think.

Relax man - no one is having a go at you. I didn't say your wrong. I'm just trying to understand your logic. Additionally if I'm wrong, I've no issue in admitting that and I've learnt something new. That's a win for me as far as I'm concerned.

What I'm saying is that in your case (assuming you had an unlimited inverter) a normal solar generation profile for a south array on a perfect day would look something like this.....

So if we introduce the inverter clipping for 6.4Kwp at 10:30am it starts to look something like this.

The shaded area is the production that your losing and that area is actually quiet small compared to the overall area under the curve (your total production). So being clipped to 6.4kw on a 8Kwp system it sounds like it's bad, but it's really not that impactful. For example at 11am your "clipped", but only a few 100's watts as it's not got to noon yet where you'd lose 1.6kw

Only on the "very perfect days" of the year will you lose any significant production, probably 2-3Kwh out of 40-50Kwh. If you lower the inverter limit to 5kw, natrually that shaded area gets bigger, but even still it's still the smaller of the two.

Then the other factor is how many of those "great sunshine days" where you would see any clipping we get a year. We can argue the case - I reckon 30-40 probably. I remember March last year was awesome, but I'd say outside of that we get maybe 4-5 days a month of solid blue skies maybe

It's a great tool PVGIS. I use it all the time.

Unfortunately the tool doesn't answer the question at hand. The tool will tell you what the production is for a panel with a specific orientation (azimuth) and slope, for the year. It has no knowledge of any inverters it's attached to, so it can't tell you the negative effect of a inverter clipping the production. There are many many days a year where (say) 10Kwp in panels would not be clipped on a 6kw (or even) a 5kw inverter. Those days your array would still produce full output and be counted in the totals for the year with either 5kw or 6kw inverter....

This goes back to the original point of the 1st post. Yeah, a 5Kw isn't as good as a 6Kw, but in reality the drop in production to the user at the end of the year will not be that bad. Which do you want? Of course your want the 6Kw, because bigger is better, but the overall % difference in output for the year is probably of the order of single digit % up until to go you to 8-9Kwp. At that stage your well into the heavy "enthusiast" ballpark.

But that's not "clipping" Murt, due to inverter sizing. That's just the difference in production due to the greater size of the panels. That's a completely different thing from clipping and why you can't use PVGIS (or the sunshine hours) to work that out. For example, which I hope will show what I mean.....

I highlighted January in both cases. The 8.0Kwp array (of course) produces some 50Kwh more for January than the 6.4Kwp does - but has anyone EVER seen "clipping" on a array in the middle of January in Ireland with the sun 20deg above the horizon?! Just doesn't happen. Sun is too low on a slant angle.

So in this case, if you had 8Kwp in panels in January......you would still generate the same if you have coupled that to a 5kw inverter, or a 6Kw inverter as the inverter isn't the bottleneck. When the clipping does start (March?) then you will see it start to happen a bit more every day. Maybe you might get it for a few minutes in March, maybe a little longer in April, etc, but it's only in June that you would see your inverter clip any decent amount and at that, for maybe 3-4 hrs you'll only lose a significant fraction of 1.6Kw on the table. The other 12-13 or so hours you'll have captured everything within limits.

When you look at the impact space verses the overall year, imapct is low

Clipping in January - in Ireland? For reals?

Don't take my word for it and perhaps this would help explain it better than I have so far. (414) Solar Clipping Explained - YouTube

Again, I'm not saying that they are equal, of course you want the larger inverter - but the effect is a lot less than you think. The idea that your being cheated out of 1000's of Kwh with 5Kw over a 6kw is simply just not true.

You said you worked for ESBN, surely you would have an inside track to know the answer to your question !!!

@Murt2 how are you getting clipped at 10:30 on 8kwp, I assume that is peak summer?

10:15 now, full sunshine, and my 8kwp S is pushing about 4kw

Also when the panels are hot in summer you'd drop about 20% anyway so you might not be clipping anything?

I'll let you know how 8kwp does on a 8kw inverter in summer I suppose

Yeah 20kwh batteries and about 120kwh in the EVs.

So two days ago it was a very good day, 45kwh, the inverter did stay close to 7kwh at peak but if you would max out at 6.4kwh this wouldn't amount to much wasted around this time of the year.

That curve is pretty perfect due to the real time values coming from the inverter, if you have 5 mins refreshes it won't look the same.

The biggest gain with this inverter is sustained charge/discharge up to 200a for when we inevitably get forced to take smart plans and have to hammer the batteries for 2-3 hours at night in winter