New system user in need of help

Hi All,

I'm not sure if this where I should be asking this but here goes..

My PV system went live last week and whilst the system is small (3kW) with a 5.2kW battery, it appears to be behaving in quite an illogical way. It's currently in eco mode and in the morning it appears charge the battery from the grid, rather than charging the battery from the PV production through the day. We're not usually home much during the day so our use is light during that time. I was expecting to charge the battery from the PV then export excess electricity to the grid/use it if we're about. Has anyone else's system done this? Is there a setting I need to change?

Today's been a really good day in terms of sunshine, but my electricity costs aren't much different to before the installation.

Just to complete the picture, I'm on Octopus Go so can charge the battery between 00.30 and 04.30 at 7.5p per kW. I'm clearly missing something but can't for the life of me see what it is...any help would be appreciated.

DeanMcG

Look at the Grid Import and Export readings. Do they look correct? ie now its going dark, are you importing from grid? Turn a kettle on, does the Import value increase by 2kw or so?

It could be that your GivEnergy grid meter is faulty or incorrectly fitted. It is not just the value (size) of the power that is important, the direction is important as well in order to determine import or export.
The first port of call is your installer.

DeanMcG Make sure you set things up in the web portal and not via the App. As the App does not always work correctly when changing settings.
Also, make sure you set it to Eco mode by enabling it and SAVE the setting; wait for the greenish message at the bottom of the screen that confirms it has saved it.
On Go, set the "Timed Charge" to 00:30 - 04:30 with the % at what you would like it to maintain* overnight. For example, it looks like it will be sunny tomorrow, so something like 20% or lower. If it is predicted to be a cloudy, then a higher percentage. Make sure you Save the setting and wait for the confirmation.
The other settings should be disabled. If not, set them to disable and save and wait for the confirmation message.
*Note: The "Charge to" phrase is misleading. What it really does is discharge to that level, if already higher, or charge to that level if lower (within a couple of %).

Thanks everyone, all of your replies are really helpful. :-)

Woodlands
Hi again,
Is there a way to stop the system from exporting from the battery to the grid? I can see the battery is charging on the overnight tarrif, but then it starts exporting it back to the grid. This makes no sense as I'm buying it, storing it then selling it back to the grid at a loss.

Is it actually exporting, or is it just using from the battery to meet the house needs? i.e. What is the discharge rate?
A screen shot of your portal screen with <Settings> selected may help make sure everyone is in sync. , another with <System Data> selected may help as well.

DeanMcG Hi again,
Is there a way to stop the system from exporting from the battery to the grid? I can see the battery is charging on the overnight tarrif, but then it starts exporting it back to the grid. This makes no sense as I'm buying it, storing it then selling it back to the grid at a loss.

Unfortunately, this appears to be a design fault in the way it maintains the % setting when it is set to below 100%.
When set to a % charge below 100% it is constantly charging & discharging by a couple of % to try and maintain that level.
When you set it to charge to 100% it does not do that; so there is something wrong in the logic which makes it do it when it is on a lower setting.
It has been commented on before, as it is a very in-efficient way of working.

Woodlands Design fault is a bit strong. When set to 100%, the charger has only one place to go. At a lower percentage, any temperature change results in a slightly different SoC being read back and the inverter has to work to maintain the target value. Reality is that the amount of energy lost in doing this is minimal (at least that's the case with the system I have)

As a start I would enable Eco mode and disable all other settings including timed charge and see how that goes. If your battery doesn't last through the night then I would use a timed charge for how long is required to get to when the solar starts to charge again.

This works for me from late Spring to early Autumn, and then I need to start to do an overnight charge again.

I found as you go along, you work out the best way to use it to meet your needs, and now it will probably take me a couple of minutes a day to change my settings (other than in Summer when solar panels generally do the charging)

One thing to remember is the Risk vs Reward equation on Go. For one hour of off peak charging you will only get about 10 minutes of peak import so I generally overcharge at night to ensure no peak use because the sun didn't shine as much as I thought the following day.

Martyn Risk vs. Reward is a good point. The reward is much better for the older deemed export FIT scheme. I currently pay 5p/kWh off peak and 13.7p/kWh peak so about 1:3 after conversion losses. Next year will be a different story but SEG payments make a big difference to the ratio.