I've starting gathering data for March on the WW solar forecast vs Solcast vs actual generation. Although it is early doors, the WW forecast does seem to be very conservative. Yesterday it underestimated by 46% and midday today it has already under estimated by 34%. I accept that my forecast is being done at 2am when the battery is scheduled to recharge so will never be 100% accurate due to weather changes after an early morning re-charge, but there seems to be a massive discrepancy with Solcast and I could easily have avoided the battery being re-charged today had the WW forecast been higher. Is there any forecast correction factor we can apply to make the forecast more optimistic if we find it is consistently under-estimating, or more pessimistic if it is over estimating? Thanks in advance for advice.

There is a "correction factor" setting in the advanced setting page. I have mine set to 0.9. This won't affect the solar forecast as much as it it affects what SoC target WW bases on it. I'm sure it would achieve the exact same thing in practice.

My forecast was massively wrong today too 😅 predicted 5.5kWh and I'm already up to 10.1kWh and it's only 1PM. It's the first one to be so incorrect that I've noticed. It's inevitable though. I noticed that most weather forecasts thought it was going to be cloudy today

@"psiloc"#p1807 Yeah it's important to not let one outlier skew the general results. I'd recommend keeping a few weeks worth of actuals vs estimates.

@"nbullus"#p1803 We do indeed have a multiplier available and will expose this in the advanced settings. Just got some further backend work to do too.

@"admin"#p1809 Thank You, a correction factor to "expected solar" will be helpful. I also experience a pessimistic WW forecast, typical between 25 and 100 % below realized . I did make a statistic over the values, but gave it up because I could not find a way to automate getting data from the WW activity log. Any ideas? Some strange results of Smart charging made me wonder: Does WW Smart charging take in account when the days solar energy is expected, relative to the time slot? Background for the question is, that I, in order to WW getting newest forecast, placed a Smart charge slot in the end of the off grid period, which today resulted in a unexpected 2 kWh charge. gummy-front

For the record, the solar forecast is fixing to be bang on for me today.

@"perfrank"#p1811 > I also experience a pessimistic WW forecast, typical between 25 and 100 % below realized . I did make a statistic over the values, but gave it up because I could not find a way to automate getting data from the WW activity log. Any ideas? Good point. We should perhaps make this available to people as a CSV download. Ultimately, combined with users actuals, we could run this against our unit tests and identify and correct under and over estimations in some cases, though we would need to be careful and need a fair amount of data. >Does WW Smart charging take in account when the days solar energy is expected, relative to the time slot? Sort of. Before 11AM in the user's local timezone, we use the same day for solar forecast. After 11AM, we use tomorrow, but there may well be a problem here where some tweaks are required. Maybe it would be better to have the cutoff for tomorrow around 14:00-15:00 local time? We'll run some unit tests around time cut offs. We definitely will need more granular calcs when baking this into Agile Octopus slots.

> @"admin"#p1815 Good point. We should perhaps make this available to people as a CSV download. > Would be nice when making statistics. > Ultimately, combined with users actuals, we could run this against our unit tests and identify and correct under and over estimations in some cases, though we would need to be careful and need a fair amount of data. Thinking loud: A moving average of realized output over last few weeks, divided by forecast for same period seems to me to be a good starting point for a correction. factor This will adapt correction to changes in whether and seasons. Should/could probably be an option in [Advanced], if realized. > @"admin"#p1815 Maybe it would be better to have the cutoff for tomorrow around 14:00-15:00 local time? I think so. Your battery should be fairly large to need next days forecast in calculation before evening. In my case, I have 12.8 kWh, whish more or less correspond to 20-24 hour use. > @"admin"#p1815 We definitely will need more granular calcs when baking this into Agile Octopus slots. Sure. Living i DK, I am not on that. It is a very British thing😉

@"admin"#1 Not wishing to over engineer a solution…. But it feels like solar forecasting would an ideal candidate for machine learning. If you can get the actual data from the inverter you could set it up to track the solar forecast, the actuals and potentially other data points such as time of year and weather forecast. It could then adjust the correction factor automatically for each individual user. This would bespoke forecast for individual circumstances, for example I have some shade factor to consider and others have multiple different orientations. No expectation for this to be done as I know you have a load of other things in the works but if you don’t ask…

I have had WW setup with Agile Octopus and functioning for only 24 hours. The solar prediction has been completely wrong. It is predicting 0kWh whereas by 10.00 am I had accumulated 1.5kWh … and it is still sunny. Because of this prediction, the battery was charged to 100% overnight, meaning today I am just having to shed the excess. This is not really how I expected the system to work, could I have set this up wrong?

Solar Forecast

nbullus

admin WOW! That was quick. So to clarify:

If target SOC is reached before next scheduled slot starts, the next charge slot will be skipped?
If target SOC is reached mid way through a charge slot, will charging stop and revert back to ECO, or will it finish that slot off before reverting to ECO and therefore SOC may go above target SOC?

admin

nbullus

If target SOC is reached before next scheduled slot starts, the next charge slot will be skipped?

The condition that gets evaluated whether to skip a slot (or adjacent block of slots) is still the "SOC less than" setting.

If target SOC is reached mid way through a charge slot, will charging stop and revert back to ECO, or will it finish that slot off before reverting to ECO and therefore SOC may go above target SOC?

It will finish the charge slot but we do set the upper charge percentage, so it shouldn't go above target SOC, just keep it at or around target SOC for the remainder of the slot or block of adjacent slots.

The reason I mention slot or block of adjacent charge slots is that the "SOC less than" condition only gets evaluated at the start of a slot or a block of adjacent/connected slots once.

So for a 4 half hour slot block say 4:00-6:00 - the condition will only be evaluated at 4:00 - because we effectively condense adjacent charge slots to one big one.

psiloc

Just wanted to bring this back to the forefront. In common with what the first few posters reported, now that the weather is better, I'm noticing that the solar forecast is too conservative.

I've actually tried cheating the settings a bit and set my peak output to 4kWh (I actually have 3.5) and WW still, pretty consistently, underestimates the solar forecast by about a third.

admin

psiloc We'll run some tests, thank you.

admin

psiloc The biggest factor feeding into this is cloud cover tbh. And if actual cloud cover for your location is 10, 20, 30% out from the forecast, which is not out of the ordinary, that's going to make a huge difference between actual vs forecast.

We're fairly confident that for sunny summer days, we're not too far off, equally after our winter tweak, we want to make sure we're not changing things just because of a few outliers.

Our aim is to look into collecting the actual solar generation at end of day for users, so we can run some analysis and stats on it.

psiloc

Understood. I know it’s a very delicate balancing act, just feeding back 👍

Capt_Rich

I've just started running a comparison between Solcast & WW forecast solar vs actual as I think I may need to tweak my settings a bit too (have 2 sides of roof)

Jaspar

Apologies for daft Q but where do I find forecast solar predictions?

admin

Jaspar We don't show/use these yet for Octo Agile. We do for custom charge and export schedules.

Tima441

Just thought I'd bump this back up.
Obviously solar is minimal at this time of year but wonder how the plans are to use this data?

If the forecast can be compared to actual production then maybe a regular factor can start to be seen? To adjust plus or minus x% compared to forecast?

But if its to be used significantly it might also need to have a further adjustment option. I'm my case I have approx 6kw solar attached via GivEnergy inverter but also a further 2kw that's non-Givenergy. My thoughts:
Adjustment e.g. add 33% for additional solar or "train" the system by manually adding data for a period of time (min 2 weeks? 1 month?) to factor in the actual production vs forecast. Using both GivEnergy and non-GiveEnergy data.

Giles

admin Good point. We should perhaps make this available to people as a CSV download.

At the risk of resurrecting this thread again:
The ability to download historical solar forecasts for each system would allow users to do their own comparisons with the actual PV generation they've previously experienced. Hence they can reach their own conclusions as to what correction factor they wish to apply for their setup. Typically I suspect I may end up using something like 0.5 at this time of year rising to 1.2 in the summer. At present I'm applying this myself by adjusting the Solar capacity (kWp) figure on the Settings page; is there a separate correction factor setting anywhere I can use yet?

admin

Giles Full Activity Log download is now available as per v0.5.1017.

Giles

admin Excellent, found it!
Having downloaded my activity history, I see the Solar Forecast column is empty, apart from a few entries last Spring when I exported to the Grid. I'm guessing you don't populate this field unless its used as part of a Smart Charge or Forced Discharge event.
At present I'm not using Smart Charge, as the predictions seem so badly off in my case. I was hoping to derive a realistic correction factor, based on the historical predictions, before using the Smart Charge feature again.
I suspect you're going top say I need to use the Smart Charge feature for a bit, to get a meaningful number of historical forecasts, to allow me to derive an appropriate correction factor for my setup, to make the feature worth using(!)
Assume there's no chance of publishing the forecast for every entry on the CSV download, or ideally just the first/last entry each day?

admin

Giles We can allow separate solar forecast figures too (as we do collect these now), we'll make that available too.

Update: solar forecast CSV now available in release 1019.

Digitalsafaris

Thanks for the solar forecast csv, which I presume is unique to our own configurations. Presumably it's also dynamic, in that I've been recording it each morning (WW am) and the figures in the download (WW csv) are slightly different. What time does the forecast for the day "freeze"?

I've also been tracking the Solcast forecast via GivEnergy and have taken care to make sure my location and configuration were the same in each app. Since 1 Jan, WonderWatt forecast has been 2x actual, and Solwise 1.4x actual.

On the 4 days when actual exceeded 10kWh the forecasts have been more accurate (WW am 0.8x actual, WW csv 0.9x actual, Solcast = actual).

Look forward to improved accuracy as the days get less gloomy and the yield increases.

admin

Digitalsafaris What time does the forecast for the day "freeze"?

We calculate it shortly after 11:00 and 23:00, which is why you may see slightly altered figures.

Digitalsafaris

admin Thanks. So the final figure in the csv file is calcuated at the end of the day in question (23:00)? However, if you are going to use the forecast to adjust settings for the day ahead, you would presumably use the figure from 23:00 the day before, or even the 11:00 forecast, depending on when you calcuoate the next next schedules?

admin

Digitalsafaris Yep, that’s correct.

gwynnej3

I'm new to this, but for my installation in CV34 my actuals are between 17% and 25% of forecasts. I shall be adjusting my correction factor when I have some more data!

gwynnej3

gwynnej3
Having said what I did, I can't see anywhere in the settings to adjust solar forecasts. I guess I will probably adjust the size of my solar kwp.

John
composed-queen

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