Afternoon - new here and got a solar system installed last week. I have installed solar assistant and one thing that bothers me is that the prediction vs actual for solar are completly off - looks like the time is oincorrect or something. For example for today I have this:

I have gone into the settings and set the gps location of my house, the tilt angle (as measured on the roof vs horizontal) and then I went into open street map and measured the azimuth at 60 degrees using the calculater as below (red is where on the roof my panels are:

So my final settings are:

This still produces the prediction above. It very much looks to me like the prediction is being done in the wrong time zone or else my graph is in the wrong time zone...

48 minutes ago, atunguyd said:

Afternoon - new here and got a solar system installed last week. I have installed solar assistant and one thing that bothers me is that the prediction vs actual for solar are completly off - looks like the time is oincorrect or something. For example for today I have this:

I have gone into the settings and set the gps location of my house, the tilt angle (as measured on the roof vs horizontal) and then I went into open street map and measured the azimuth at 60 degrees using the calculater as below (red is where on the roof my panels are:

So my final settings are:

This still produces the prediction above. It very much looks to me like the prediction is being done in the wrong time zone or else my graph is in the wrong time zone...

Could you indicate what panels as in quantity and size as well as the inverter used. This can be a guide towards your prediction.

38 minutes ago, Scorp007 said:

Could you indicate what panels as in quantity and size as well as the inverter used. This can be a guide towards your prediction.

Yeah sure it is 16x560W JA panels and a Deye 12Kw single phase inverter. I have input into solar assistant the max solar power as 8960W

Edited July 29, 2025Jul 29 by atunguyd

59 minutes ago, atunguyd said:

Yeah sure it is 16x560W JA panels and a Deye 12Kw single phase inverter. I have input into solar assistant the max solar power as 8960W

Even if you can use all the PV power the prediction looks very optimistic. 35kwh at a maximum looks more in line than the 48kwh indicated.

Most of us have around 25% of PV wasted with lowish loads and battery fully charged.

Thanks - today I did get close to predicted total - see below - I generated 41.4KW today which is very close to the prediction.

That is not what I am asking about - I am more interested in why the predicted graph has such a delayed time offset to it compered to what I actually get. This has been every day so far. The prediuction is that I will start to generate decent power (ie over 1kw) at 9am but as you can see at 7am I was already generating that. The prediction then said that I would peak at 1pm but I peaked t 11am. Prediction said it would drop at 5pm but in fact it dropped at 3pm. As I said it seems to be exactly 2 hours ahead which makes me think this is a time zone thing. I can confirm that the actual readings are what I was getting at those local times, so the predictions seem to be ahead by 2 hours. The time in the inverter is set to local time, The time settings in solarassistant as as below, so I really dont know what could be wrong:

I suggest you email solar assistant themselves, or contact them on WhatsApp at +27870931601

This new "prediction" part is still being rolled and I suspect still being tuned. Regard it as experimental until a full roll out has taken place
I actually contacted them today as mine does not even have it yet.
Their response was "Read the release notes" i.e. refer to "This update might not show immediately on your device as it's being rolled out in phases."

My own thoughts are it will be similar to what the international providers of these prediction models use as well, and I have been using Solcast for a long time.
Both Solcast and Solar Assistant state quite clearly you can only input one set of panels based on the same orientation. Thus if one has two panel arrays with different orientation, then you need to run two separate accounts on Solcast. Obviously with SA you are limited to your single account.

As for the time offset, I would check with them. It may well be that the UTC offsets may not be correct as yet. They need your feedback

Regard it as a nice to have and indicative. It's as reliable as weather forecasts, and you should know the probability of accuracy there.

Edited July 29, 2025Jul 29 by zsde

20 minutes ago, abd7 said:

I suggest you email solar assistant themselves, or contact them on WhatsApp at +27870931601

Thanks - their FAQ does mention to ask for community help here first which is what I did. Perhaps it is a bug in their system.

9 minutes ago, zsde said:

This new "prediction" part is still being rolled and I suspect still being tuned. Regard it as experimental until a full roll out has taken place
I actually contacted them today as mine does not even have it yet.
Their response was "Read the release notes" i.e. refer to "This update might not show immediately on your device as it's being rolled out in phases."

My own thoughts are it will be similar to what the international providers of these prediction models use as well, and I have been using Solcast for a long time.
Both Solcast and Solar Assistant state quite clearly you can only input one set of panels based on the same orientation. Thus if one has two panel arrays with different orientation, then you need to run two separate accounts on Solcast. Obviously with SA you are limited to your single account.

As for the time offset, I would check with them. It may well be that the UTC offsets may not be correct as yet. They need your feedback

Regard it as a nice to have and indicative. It's as reliable as weather forecasts, and you should know the probability of accuracy there.

Thanks - as a new ueser I was not aware that this is a new feature - so perhaps I should let them know that there could be a time offset issue.

8 hours ago, atunguyd said:

Afternoon - new here and got a solar system installed last week. I have installed solar assistant and one thing that bothers me is that the prediction vs actual for solar are completly off - looks like the time is oincorrect or something. For example for today I have this:

I have gone into the settings and set the gps location of my house, the tilt angle (as measured on the roof vs horizontal) and then I went into open street map and measured the azimuth at 60 degrees using the calculater as below (red is where on the roof my panels are:

So my final settings are:

This still produces the prediction above. It very much looks to me like the prediction is being done in the wrong time zone or else my graph is in the wrong time zone...

Just a thought - really just taking a chance - try to set your Azimuth to 300 degrees and see how it looks.

It might be, if this is a new feature being tested, that the degrees are being counted anti-clockwise rather than clockwise. Basically, I'm wondering whether your panels aren't being interpreted as pointing 60 degrees West rather than to the East.

10 hours ago, GreenFields said:

Just a thought - really just taking a chance - try to set your Azimuth to 300 degrees and see how it looks.

It might be, if this is a new feature being tested, that the degrees are being counted anti-clockwise rather than clockwise. Basically, I'm wondering whether your panels aren't being interpreted as pointing 60 degrees West rather than to the East.

Thanks @GreenFields that did the trick - the time when PV kicks in is much more accurate now:

azimuth = azimuth - 180

https://solar-assistant.io/help/dashboard/pv_forecast

Glad to note solar assistant have added some clarity on their website regarding the new features

13 hours ago, abd7 said:

https://solar-assistant.io/help/dashboard/pv_forecast

Glad to note solar assistant have added some clarity on their website regarding the new features

From the link: Azimuth ranges from -180 to 180, where 0 is south, -90 is east, 90 is west and 180/-180 is north.

Why, oh why, are they turning every convention on its head? Feels like a dystopian world where everything has an opposite meaning to what you think it should.