I have just noticed that my panels are being restricted to approx 3.6kW output. The sun is blazing and I know I can get over 6kW. It seems to happen about when the battery is full up. I am sending approx 3kW back to grid, and using approx 600w indoors so am not calling for power from the battery. Is this normal behaviour for the system? If so, where is the other kiloWatts going??? My inverter is Gen1 3.6kW and 9.5 battery and 6kw panels.
Steventon22 if your battery is full and you're exporting then you may be limited to 3.68kWh under G98. Also the 6kW for you panels would be under direct sunlight, south facing, at the correct angle.
Cdent Thank you for that info. I have just read up about G98 on Google. So do I understand correctly that most solar panel owners are only able to send back 3.6kW? Seems a bit daft to me, as I can contribute to the grid a lot more. I have the ideal layout, south facing on a good slope roof, and “full-on” sunlight, so I know I produce good amount of energy. Any idea where my excess generation actually goes? Is there dissipation of 2kW++ happening inside my garage? Or is it some-how checked by the inverter?
Steventon22 , the excess solar energy ends up as extra heat in the solar panels.
Remember that solar panels are at best 21-22% efficient at generating electricity, so even when all possible energy is going through the inverter, there is still 78% ending up as heat in the panels.
Limiting the throughput of the inverter just results in say 10% electric and 90% heat at the panels.
This whole export limit thingy in the UK seems bit daft to me - I spend most holidays in Germany (Schwarzwald region) and we in the village where we stay there are houses with 40+ solar panels (yes their houses are much bigger then ours here) and based on what people over there told me and my vague understanding of the German language there are no major obstacles for them to do that.
Steventon22 inverter is Gen1 3.6kW and 9.5 battery and 6kw panels.
I would have thought a HY5 would be more suitable to 6kWp panels that HY3.6. Anyway, the maximum output from the HY3.6 is 3.6kW AC. That's why you can't export mare than 3.6kW. Your installation will likely have been put in under G98, also limiting you to 3.6kW export. The inverter will be able to use more than 3.6kW from solar, but only to charge batteries (2.5kW to battery at the same time as 3.6kW to house/export).
alfwro aren’t they on 3 phase circuits out there?
Steventon22 my export got set up around midday (when the export meter read was registered on kraken on octopus). My PV output wouldn’t go above 3.8kw. My systems been commissioned since mid feb and I’ve seen the max output from my panels around 4.4kw (ie not far off their maximum) when the sun has been out in the afternoon.
I’m glad you asked this question today because I was wondering why on earth on the best day we’ve had so far my panels weren’t pushing out their maximum!
Edit: I’ve just read the other post about output. Who knew on a clear day max PV could be lower than when the sun pokes out from behind clouds on a different day!
Yes, same for me today. More sun than yesterday but the batteries were full by 11.30 and then output clipped to 5kw whereas I saw well over 7kw yesterday. My export limit is also 5kw. So today I managed 37kwh generation whereas yesterday was 41, even though today was full sunshine most of the day. So more reason to start a bumper solar day with plenty of battery capacity. Every day's a school day!
sponev if you want to reduce the clipping at peak solar output then reduce the battery charge rate on sunny days so that the system exports more early in the day, then at the peak you still have battery capacity to charge into while exporting up to your limit as well.
possibly could be automated by script/HA but just setting the charge rate manually early in the day and resetting later does the job too.
Steventon22 Why have you only got a G98 rather than a G99 if you can export more than the G98 limit? Surely this "limit" needs fixing first
Steventon22 all to do with individual DNOs trying to manage their local grids. The country wants to move towards a more greener future, this is one way to do it but we have old technology that they aren't willing to (pay to) upgrade as it doesn't bring them much of an income!
These are all really helpful replies. Thanks a bunch. I now understand much better what is going on.
I suspect that my best answer would be to invest heavily in some more battery storage rather than just the one 9.5. This would surely enable me to get the most from the panels during full sunlight, and reduce the PV clipping that is going on. Not sure if it is worth shelling out £4000 or even £8000 just to see the givenergy app. behave as I want it to, especially over winter months!!!
Steventon22 especially over winter months
Is the reason I chose two batteries, I can run all day after a cheap overnight charge.
All is now perfectly clear. Here is a shot of the situation today, sunny blue sky, and generating a healthy 5.58kW. The battery is charging nicely, and sending back to grid 2.1kW. So, when the battery is full, the most I can send back to grid will be approx 3.6kW, even if sun stays out well. Leaning curve now over. I hope this helps other readers!
Your battery should be charging at 3.6kw or have you lowered the charging limit from the max? I would also invest in a solar diverter for for hot water to mop up that extra solar...much cheaper than a second battery if you have an immersion heater.
Just read that you have a Gen 1 inverter so 2.5 kw max output is correct.
Steventon22 Yes, there is a learning curve but actually quite fun. Like the post above, we also have 19kwh of storage and still manage to fill it, do all of the domestic stuff, car charge and end up exporting. This should be fixed when our ASHP goes in and we switch away from gas. It's a bit of number crunching to decide just how much battery capacity you need versus the cost of installing it but over winter, charging overnight on cheap tariffs, it certainly makes a huge difference.
Yes, all noted, thanks. I have a Solar iBoost+ for the hot water, it will come up trumps as we get into summer months. I am also having Air-con installed with heat-pump outdoor unit, naturally driven from the solar power during daylight, for three rooms, as my wife gets a bit down with the summer heat we get. The heating benefit will come for next winter, when we can heat three rooms with SCOP of 4.3 using generated electricity. Done the sums, and it will work out considerably cheaper than turning on the gas central heating. We shall wait and see.......
By the way, if you are considering purchase of iBoost Buddy, be aware that the LC D display leaves a lot to be desired. Looking face-on, you get loads of redundant information trying to show through. From an angle of about 45 degrees, the LCD screen is perfect. I have it from the Manufacturer (Marlec in Corby) that they know of the design fault, but have no plans to correct it. Just advising, really......
Steventon22 Ah good stuff. We have an Eddi going in next week which will save me keep switching the immersion on and off! Also a Daikin air-to-air system (5 units) which is currently in for planning approval. Hopefully that all goes as planned as it should reduce our gas to nearly zip. Quite an outlay but still a decent pay back, even if utilities start to come down a fair bit. Plus the environmental benefits of course.
You might find the link interesting
reading.....
https://www.planningportal.co.uk/permission/common-projects/heat-pumps/planning-permission-air-source-heat-pump
The bottom line is that I do not need planning permission as all the criteria are satisfied with ease. It would probably be a different matter if I installed full Heat Pump central heating, as things start to get a bit on the large size re. the outdoor unit!!!
Steventon22 I've been through it with a fine tooth comb trying to avoid planning but can't unfortunately. We have two outdoor units proposed plus watch out for the condition which says "used for heating only". Lots of folk are tripping up with air-to-air over that apparently.