Renewables: "talking 'bout my generation"

shavy65

I like your profile pic Django

Rheumatoid

Should those with capped systems used the capped size rather than actual when calculating O's and should any PVGIS estimate be based on the capped size?

Strange what enters my head in the middle of the night :rotfl:

Martyn1981

Rheumatoid wrote: »

Should those with capped systems used the capped size rather than actual when calculating O's and should any PVGIS estimate be based on the capped size?

Strange what enters my head in the middle of the night :rotfl:

Hiya. It would distort the figures. In my case a cap of about 3.68kW would have little effect at all on annual generation, so my O's would jump dramatically.

If you take the question to the extreme (just to test it) and impose say a 1kW capped inverter, many (most?) of us would see summer O's of perhaps 10 to 15. I'd certainly expect days of nearly 1kW from 6am to 9pm, so 15 O's, whilst halving my actual generation.

Lastly, most folk with 4kWp and a 3.68kW inverter, probably see next to no real capping, but would see an 8% uplift in Os.

[ Not that I spend time pondering such things ..... ;-) ]

Rheumatoid

Martyn1981 wrote: »

Hiya. It would distort the figures. In my case a cap of about 3.68kW would have little effect at all on annual generation, so my O's would jump dramatically.

If you take the question to the extreme (just to test it) and impose say a 1kW capped inverter, many (most?) of us would see summer O's of perhaps 10 to 15. I'd certainly expect days of nearly 1kW from 6am to 9pm, so 15 O's, whilst halving my actual generation.

Lastly, most folk with 4kWp and a 3.68kW inverter, probably see next to no real capping, but would see an 8% uplift in Os.

[ Not that I spend time pondering such things ..... ;-) ]

I guess my thought were mainly around unfair advantage gained by those with big systems and no capping.

ajbell

2.77 Os yesterday and today could be similar.
Managed to divert 7kWh yesterday.

Martyn1981

Rheumatoid wrote: »

I guess my thought were mainly around unfair advantage gained by those with big systems and no capping.

I think the million dollar question is, 'is there any capping?'

Just because an inverter is undersized, doesn't necessarily mean that there is any annual, or daily loss. There may at certain times of the day (good sun, clouds and cold panels) be some brief capping, but that is hopefully made up for during low generation times, when the smaller inverter is more efficient.

In the UK the industry suggests that inverters should be undersized by 10-20%, though each situation needs to be considered carefully, such as a south facing install in Cornwall may want 0-10% undersizing, whereas an off-south install in the north may favour 20%.

In my case I have 5.9kW of inverters, never see sustained generation above 4.2kW, though spikes of 4.9kW are possible. So a single inverter of approx 4kW, would probably be better, and improve annual generation.

Some folk on here with large undersizing (so to speak) have posted extremely good annual generation.

Is it wrong that I find this stuff so interesting?

Rheumatoid

Martyn1981 wrote: »

Is it wrong that I find this stuff so interesting?

no, I'm glad you do. Who else would answer my questions :rotfl:

Merlin139

3.033 O's here today.

Well happy with that!

Rheumatoid

2.7 O's here today

ajbell

2.75 Os today and just past PVGIS.