Clipping and how to maximise solar

floydmoon12 · 21-03-2026 04:05PM #1

I have a 10kw solar panels system. 12 south facing and 8 west facing. I have a 5.5kw inverter and a 9kw battery. I understand the concept of clipping and the reason behind oversizing but after using Chatgpt it seems to give me varying answers to how to best utilise and if what I am asking is possible. Is it possible to get more than 5.5kw from your solar on sunny days like this. If I am charging the battery or using a lot in the house can I take more than the inverter limit. I ask this as for periods of time the system is registering that I am getting more than 5.5kw but then it flatlines. Here is what I am seeing today with the flatline being at 5.5kw.

graememk · 21-03-2026 05:48PM

https://www.boards.ie/discussion/2058436164/clipping-and-how-to-maximise-solar

What inverter do you have

floydmoon12 · 21-03-2026 05:52PM

sigen energy controller

graememk · 21-03-2026 07:50PM

Ah, no experience with them, the solis has a mode called feed in priority where it exports first then charges the battery rather than charge the battery then export.

I'm doing it on a deye via home assistant (by changing the battery charge current setting to do the same)

Barry5714 · 21-03-2026 08:44PM

When u know ur in for a sunny day force discharge the battery in the morning and lower the charge current so u can put into the battery what would have been clipped.

Inverter not needed for excess dc power from panels to pass into the battery.

Paul Kiernan · 23-03-2026 01:58PM

https://www.boards.ie/discussion/comment/124330763#Comment_124330763

So are you saying that in the first picture the battery was charged and couldn't take the excess so it was clipped but in the second picture the excess could go into the battery?

Barry5714 · 23-03-2026 06:34PM

https://www.boards.ie/discussion/comment/124334596#Comment_124334596

Ya that's exactly right.The first pic produced 36.5kwh. The second 43.5kwh.

Probably gaining 5 or 6 kwh hard to say exactly because of 2 week gap between 2 examples.

That's with 5kw inverter 7.5kw pannels facing sse and 10kwh battery.

bullit_dodger · 23-03-2026 09:10PM

Most people completely over estimate the amount of loss which happens as a result of clipping. Sure if you can avoid it, that's a good thing, but to take your example above, and put some numbers on things to get a context.

All your losing is the bit in red above. If you remember your leaving cert math and you knew the formula for the curve you could integrate and find the area, but to get a rough idea…..we can pretend it's a box of say (5.7kw - 5.2kw) x (6 hrs) = 3kwh and then take 2/3 of that (since it's not a box) … giving us ~2kwh or so.

Since you generated 36Kwh that day, the clipping loss is approx. 5% or there abouts. If that's exported, you'd get what €0.40/day. Assuming you have 50 of these days a year, you would "save" €20/year if you had no clipping.

So while it's annoying to see it being lost…..really it's not a big deal

Soarer · 24-03-2026 08:55AM

All I can think of there is your battery was full and your system clipped the production as it had to convert from DC to AC and export.

To maximise your solar with the Sig, you need to make sure there's room in your battery to store energy direct from the panels. So if you know it's going to be a sunny day, drain the battery to what you're comfortable with, and let it fill unhindered. You can still have it discharging while it's DC charging. So your app will say solar is 6.5kW (or whatever), to grid will be 5kW, and battery charging will be 1.5kW.

Here's my system on the same day. More natural curve compared to yours.

slave1 · 24-03-2026 12:21PM

https://www.boards.ie/discussion/comment/124335698#Comment_124335698

I'm happy out when clipping, means a great day, a nice event to see happening and nothing to be worried about

TimHorton · 24-03-2026 01:40PM

https://www.boards.ie/discussion/comment/124335698#Comment_124335698

Not true in my case , Clipping would have lost me all the production above the Orange Line (5.5kW) , I think you will agree that is far more than a 5 % Loss. I generated 51 kWh on this particular day.

slave1 · 24-03-2026 03:21PM

But you are in N7 territory so should be no clipping if you have increased MEC

bullit_dodger · 25-03-2026 02:54PM

https://www.boards.ie/discussion/comment/124336951#Comment_124336951

To do a similar exercise assuming it was a rectangle at (8.0kw-5.5kw) x (5 hrs) = 12.5Kwh, and then take 2/3 of that since it's not actually a rectangle. You'd have 8-9kwh ballpark clipped.

So you would have lost circa 17-18% of your production that day. To be fair though, your in NC7 terrority with that setup and I'd wager 90% of the solar installs out there have less than 8kwp. My own one with 8.8kwp is an outlier really. Sure there are people with 10+kwp here on the forums, but they are few.

Again, I'm not saying that clipping is irrelevant, only that for the vast majority of people out there when they see clipping they want to fix it by getting bigger inverters etc and with a payback of in the example above where you might save €20/year, the return on investment is pretty long.

ptogher14 · 25-03-2026 03:31PM

In normal operation, the inverter will prioritise charging the battery. On high yield days this will mean your battery could be slowly charged to 100% before midday. Come afternoon you will then see peak generation. In my case slightly over 8kw. The inverter will put 5.5 to the grid and has to clip the rest as it has no where to go.

If the inverter can be set to prioritise feeding the grid, behavior is different. Morning sun will keep the load going and feed excess to the grid. Come the afternoon when you are seeing higher generation 5,5 will be sent to grid/load and excess can go into the battery as there is head room in it. Downside with this mode, is on low yield days you may run out of battery so ideally you are making a choice given the forecast predicted on any given day.

I'm new to solar and only started looking at this in the last few weeks. Plenty of knowledgeable folk on here. For myself, what started out as trying to minimise clipping has turned into running automations daily and choosing whether to run in self use mode or feed in mode. If its a case usable battery capacity and forecast PV is greater than forecast load, i will run it in feed in tariff. I'm only trialing this at the moment so could be proven wrong.

As someone mentioned clipping is not a big deal but nice to know you are getting the most out of the system and maximising the ROI. Plus there are some that just like tricking around with this stuff.

For reference the system is 8.8 kwp, solis 5kw hybrid inverter and 15kw of battery. Obviously a lot of variables on systems to find what works best.

mjatkey · 25-03-2026 11:41PM

https://www.boards.ie/discussion/comment/124339933#Comment_124339933

Don't be using that PV to charge your battery, switch supplier to Pinergy charge that battery to say 90% at .06cent per KW between 2-5am, run the inverter as Feed in all the time, if inverter does clip DC will go into the battery. All PV not used by house load can be flogged back at 25cent per Kw, plus any surplus in the battery after say 10pm again can be flogged back.

Then come 2am rinse and repeat.

I charge to 100% 26Kwh of storage as half our panels are north facing so the chances of clipping are slim to none.

ptogher14 · 26-03-2026 08:42AM

Hi Mjatkey,

I currently am on the pinergy rate. You mention if the inverter clips it will send power to the battery. Can you expand on this as its not my understanding of clipping. As i understand it, clipping is power generated that can not be used in anyway. IE when there is no head room in batteries and the inverter is at maximum AC output.

Using the inverter in feed in mode will not suit everyone. I am guessing it works for you as you have quite a large battery which will cover your daily usage. I have a a 15kw battery. 12.75kw of which is usable, not taking losses into account. My average daily usage is 21kw, meaning I need to make the remainder with PV. If i run the inverter in feed in mode every day, on days I produce less than this difference I am going to fall short. On those days I am running it in self use mode.

As I said newbie to this and I am only starting to mess around with it, so I am open to correction.

mjatkey · 26-03-2026 11:27AM

https://www.boards.ie/discussion/comment/124341343#Comment_124341343

Inverter will send power to battery like you say only if there is room in the battery, hence why I say only charge to 80-90% on EV rate if you know there will be a lot of PV next day this "headroom" would allow for any clipping.

Ok, so are you on Pinergy EV plan, 3 hours at 0.06cent and 21 hours at 0.40cent? If not then you will probably be better off switching and charging battery to 80-100%.

Then come 5am the inverter will start to use the battery for any house loads, and this time of year hopefully sun will be up by 7-8am supplementing the battery usage.

If you run Home Assistant you could create a few automations to switch from Self use to Feed In and vice versa based on PV generation, I'd ask Solis for an opinion on doing this though as their inverters can be a bit flakey at times. (Two properties and 5 Solis inverters since 2024).

ptogher14 · 26-03-2026 12:29PM

I'm currently using HA to select the storage mode and set the SOC depending on the forecast. Seems to be working well……when it works! Has been working all week and then nothing ran last night. As you said the datalogger seems very flaky, which is a bit annoying. The integration keeps dropping and showing unavailable. Has anyone found a work around here? What caused the change in Solis inverters for yourself?

olympicweights · 26-03-2026 03:57PM

I'll always ensure my battery is less than 95/96% charged by late morning just in case there is excess power available. My inverter is set to feed in priority unless in the depths of winter and I want to top up batteries (I have 32kW - not that I can fill them in 3 hours and 7.9kWp panels). Screen shot of clipping below from a couple of weeks ago…

mjatkey · 26-03-2026 09:22PM

https://www.boards.ie/discussion/comment/124341841#Comment_124341841

There a few "local" Solis integrations on HA which don't rely on the Solis Cloud, a couple enable both local and cloud access.

https://github.com/Jumpy07/Solis---SolisCloud-and-Home-Assistant

I actually have all the bits for this one but never got the courage to try it having boorked two inverters already.

I use LAN connection to the loggers but still use cloud with a 60 second refresh on both inverters.

Two failed inverters I think were down to me running scripts that were just constant, although the R&D guys in China said probably not. The third failure was failed out the box brand new. Took about two months for me to prove it was their inverter and not my Seplos batteries.

Eventually they sent me a another this time reconditioned inverter which worked fine straight out the box, to be fair they did send me €200 for my troubles.

mjatkey · 26-03-2026 09:28PM

If you can get another AC supply to the batteries you can run additional chargers (rectifiers) to add more to the batteries in the EV window. I have a Huawei (3KW) and Eltek (2Kw) on each set of batteries affectively doubling my charge capacity in the EV window.

Don't have an actual EV yet and still use gas to heat the water, if you have these and heat pumps this is when things get tricky as a few guys on here will tell you.

Theres an Emerson thread on here.

ptogher14 · 26-03-2026 10:12PM

I was doing some reading up on various options this evening. Ideally I'd like to keep app visibility. The github link looks like the best of both worlds. Don't know how confident I would be in taking it on. If you ever get around to it come back and let us know.

I've been following the Emerson thread with interest. I may go that route.

magicbastarder · 27-03-2026 10:10AM

https://www.boards.ie/discussion/comment/124336951#Comment_124336951

yeah, you've probably lost about 20% there.

but it's a large install, and it's a trade off - what you gain is more output on less sunny days, but lose some of the output on very sunny days. clipping will be inevitable.

https://www.boards.ie/discussion/comment/124336768#Comment_124336768

this is the attitude i take.

installing a system which will go well above the inverter capacity is like buying a ferrari and lamenting that you still need to stick to the speed limits. just means you can get to the limit faster…

oaklands · 27-03-2026 01:14PM

https://www.boards.ie/discussion/comment/124343402#Comment_124343402

@mjatkey Have you considered using the immersion to heat hot water during the EV window. Should cost less than gas?

You could still use gas to supplement it if necessary during the day.

mjatkey · 28-03-2026 09:08AM

https://www.boards.ie/discussion/comment/124345193#Comment_124345193

Thanks oaklands, yes to be completely honest once the house heating is no longer required I do use the immersion a couple of times a day as we are a small household and we don't use a huge amount of hot water anyway.

Clipping and how to maximise solar

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