I'm testing out timed discharges as I'm on Octopus Flux. Ideally I would have liked to do an export this evening, but it didn't happen because the solar forecast was too low. WonderWatt calculated it as 8.1kwh for tomorrow, which is very low. Solcast is forecasting something in the region of 33 kwh, which is closer to what I would expect.

@"godfreym29"#p12 Hi, it is an estimate that relies on the cloud cover factor, among a few other things, you can see in the FAQ: https://community.wonderwatt.com/d/5-wonder-watt-faq It does look like cloud cover is predicted to be 88% for your location. That basically has a big impact. How has it been on previous days? Our aim also is to introduce the personal correction factor which you can configure if the estimate is always over or under.

Same question from me in that I had to go back yesterday to manual GivEnergy timed export for flux as wonderwall had solar forecast at 3.2 whereas solacast had it above 10. I know that weather prediction is changeable so it might be the different in the range of solar predicted in the following day, but in truth in 80% of the days, I generated greater than even higher solacast prediction so even their prediction can be low.

@"Dai"#p15 Thanks Dai - so a correction factor/multiplier of 1.4 or such might work well for you?

@"admin"#p17 it might so long as it was allowable to be big enough, even solar install is different in location and efficiency of the panels, but it’s a balance of too many customisations available to user (increasing the complexity) and setting the base algorithms the best they can be. The figure used in my prediction yesterday which caused the automation not to fire was 3.2kw for the day, I passed that by 10am this morning and I am south west pointing roof which therefore would normally peak at around 2pm. I would try it again tonight but being a special day being the last really high export rate price for flux, aim to manually dump everything tonight so haven’t set the trigger to fire. Will try again the start of next week but maybe it would be good to see somewhere in the app in the short term what the prediction is for the following day and allowing the user to make a judgement in advance rather than relying on looking at the logs to see the failure reason after the event which in many occasions be too late?

@"admin"#p14 Hi, so far today I've generated just over 2 5kWh and may get another 2 or 3 before it stops for the day. Quite different from the 8 that WW forecast. I did a manual Export last night and managed to refill the battery today and still exported 13 kWh

@"godfreym29"#p19 Yep, it's a rough estimate, and largely based on cloud coverage. You could of course always set the threshold lower. Great suggestion in terms of seeing a 'current prediction' for the next day. Though we probably need to keep the number of real-time weather lookups limited for those purposes to a set number of times per day, as there is a cost involved. We'll put it on the ever-growing to-do list! Thanks!

I've set my threshold to 1kWh for the forecast (bit extreme I know!) but has been working well for me for the last few days.

Like @"MartynK"#5 set an extreme low solar threshold yesterday to ensure it fired and it worked fine. @"admin"#1 mentioned the additional cost to them of providing a solar forecast in advance each day to a user and we are beta testing phase so it’s a balance between cost and speed for any software changes Maybe a quicker alteration for smart export is via the UI allowing the user to select to export based on an existing SoC level at the time of peak period OR the SoC & solar forecast. Every time the smart export fires, the solar forecast is provided in the activity log, then over a period of time user will build up understand over a period of time what the “right” solar forecast is for them and from developer cost perspective you don’t incur the extra cost of multiple external calls at this time. At the moment, if others are like me because it’s new we are at this point of time learning the best way to use the software and maybe after a couple of weeks of activity logs we would get to know the right solar forecast thresholds for our site and usage patterns.

@"Dai"#p25 Yeah, by setting the threshold as low as 1kWh - you effectively achieve exactly that, it basically only takes into account the SoC, as the kWh estimate is always above 1. Like @"MartynK"#5 's solution really.

@"admin"#p30 yep, realised similar as soon as I hit the send key (it was early, maybe too early, on a Sunday morning😉), will run it at solar prediction of 1 for the week and a high battery percentage report back as my battery this time of the year can hold 2 days of home consumption so I have a fallback

How is the solar forecast calculated?

psiloc

Hi there,

Love the application, it's exactly what I've been looking for.

Just wanted to echo the last few reports of the solar being over estimated. Last night the solar forecast was 4.8kWh, but I'm only on track to achieve about 1kWh. It did, however, correctly decide to charge the battery to 100% which is ultimately all that matters.

Just throwing it out there, but what are the chances of the forecast algorithm using actual generation data from the inverter vs. what was forecast to determine a bias over time for my account and apply it to the forecast?

admin

psiloc It's quite interesting actually, today in sunny Wales(!!!), WW forecasted 18.9kWh and we're currently on 17.3kWh and the day isn't over yet...

It's tricky really as it is based on weather forecast/cloud cover. Historic or actual generation would likely make little difference as the weather changes compared to the forecast just differ too much most of the time.

psiloc

admin No worries! Thanks for the reply.

You'll have heard this lots of times already I'm sure but if you could implement dynamic schedules that use the Octopus API for Agile and Intelligent you really would have a killer app on your hands here.

admin

psiloc Thanks for the kind words, much appreciated.

We're already testing Agile Octopus dynamic 30 min charge slots out, see the thread here:

https://community.wonderwatt.com/d/63-agile-octopus-integration/6

Not sure on Intelligent tariffs (not actually on Octopus ourselves) - are you talking about the dynamic cheap slots Octopus send out now and then? We would need to understand whether there's an API for that, I suppose there would be, tho might need Octopus API token.

psiloc

admin Yes exactly.

Similar to Agile, your users would want their battery to know about the smart charging slot to either charge the home battery or at least, prevent it from discharging into the EV. I suspect it's probably slightly simpler to implement than Agile to be honest because you won't have to worry about the half hourly unit price, just the fact it's off-peak and when.

I don't know if it's useful to you but this home assistant plugin claims to be able to get this data from the Octopus API, if there might be some code you could pinch:

https://github.com/megakid/ha_octopus_intelligent

admin

psiloc That's great, thanks for the pointer!

psiloc

Not expecting a reply, but just wanted to report that my solar prediction for today is 5.6kWh and there is not a cat in hells chance I will generate anything close to that :) we're forecast almost total cloud cover all day.

I know you're very busy (and working for free) so don't think I'm trying to put pressure on, but I just wanted to say that if you have access to my account/location/setup then feel free to use it for analysis.

admin

psiloc Hi - your predicted cloud cover for today was 72%, which (amongst other things like your PV setup) resulted in that specific kWh prediction. Weather forecasting is unfortunately not always reliable. 😔

psiloc

Can I ask what the solar forecast would have been for me on the 9th? If you can go backwards? That was our last sunny ish day and I generated 8.7kWh

admin

psiloc If you can find out what your cloud coverage percentage was that day, we can calculate it for you.

At 50% cloud coverage, it would have predicted: 7.6kWh
At 45% cloud coverage: 8.0kWh
At 40% cloud coverage: 8.4kWh
At 30% cloud coverage: 9.1kWh

So if you had a fairly sunny day, that seems a fairly reasonable estimation.

psiloc

Thanks! About 20% cloud cover average on that day from the look of some random website I just found. So yeah pretty close! A little on the high side again though so I'm starting to think I just lower my solar capacity setting to correct it.

At this point I'm just asking stuff because I'm enjoying thinking about it to be honest, so don't mind me if you don't want to, but have you considered putting a manual forecast correction slider somewhere in the settings page? Like in my case now rather than fudging my other settings I'd just correct it to -1.5kWh or something.

This could also be how people who know they get shading on their panels could deal with that.

admin

psiloc It's all good! :-)

Yeah, we have a correction factor in the backend for each user, but currently not surfacing it.

The truth is, if you were to tweak it from day-to-day based on the previous day, it would be rather counter productive, as the main point is for the automation to do the heavy lifting and for the user to be pretty much hands-off as much as possible.

psiloc

Sorry, but I have another related to question. Aside from the solar forecast, how is the battery charge target subsequently calculated?

I have a forecast of 9.2kWh today, which looking outside is probably going to be pretty accurate so that's fantastic, but WW still charged my battery to 100%. I have a 10kWh battery and had a daily use target of 13kWh set. Perhaps I'm not thinking hard enough about it but on a basic level I'd have assumed it would have only charged the battery with 3.8kWh (13 - 9.2), plus maybe a little buffer?

admin

psiloc Yeah this has come up before, and needs looking at and likely requires some simplification.

Stay tuned!

psiloc

admin Just wondered if you'd made some changes to the battery charge level calculation as of last night?

It predicted 7.1kWh of solar and set the charge level to 55%, which is fantastic!

Pourl

I have had zero kWh hours Solar Forecast in my Activity Log since 2/1, yesterday (16th) was end to end sun with minimal high cloud around 15:00, and showed up in the forecast previous day. Any idea why this would be

Most of Jan is probably correct, although we have had short bursts of sun.

admin

Pourl Only the Smart charge schedule currently calculates the solar yield forecast.

Fixed charge schedules don't need that calculation. We also haven't baked this into the Agile Octo conditions (yet).

Pourl

admin
Doh! Obviously, sorry.

admin

psiloc Nope, nothing yet. Didn't want to make rash changes without properly testing it.

psiloc

admin Hm, very strange that it's behaving so differently today then. Maybe it does need to be simplified :)

Very happy anyway

admin

psiloc Hmm, let's see what our 'simplied' version would have done for your values:

batteryKWhCurrent = (currentSOC / 100) * batteryCapaityKWh * 0.9
batteryKWhTarget = dailyUsageKwh - (batteryKwhCurrent + solarYieldKwh)

Plugging your values in:

SOC: 49%
Battery capacity: 10
Solar yield: 7.1
Daily usage: 12

Ends up with batteryKWhTarget of 0.49 KWh, which would be below your set Min SOC of 30% which would have been the target instead, and due to the fact that your current SOC is 49%, it would have kept your battery at 49%.

Happy for improvements to this formula - it definitely needs a buffer of sorts.

I'm worried it would leave people with empty batteries, especially as the KWh prediction isn't reliable for small differences which will end up having a bigger effect on people with smaller usage and battery capacity.

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