Why is my Solis solar inverter drawing energy from the grid?

Thanks for confirming, @davericho - I’d love to hear back from you post installation so we know how it went, any unexpected complications or pleasant surprises. Do you need to let the DNO know?

This is also something I’m keen on hearing back on @Mbu1982...

My installer says my system does not require DNO approval @Tim_OVO certainly update you when installation done, also I am on the old FIT generation covered by Ofgem

I have a new solar system, so this is my first few months of production. That being said, I did a lot of research before installing my system (I tried anyways, some of it doesn't make sense until you have a system installed), and I have a spreadsheet every month of exports from an emporia energy monitor (CT's on individual circuits and my mains) as well as an export from my inverter, and an export for every 15 minutes from my power company. All the data is within 2-3% accurate of each other for production/consumption.

@charjes9 nice to hear sounds like you have a good system, was your system installed by a local company? how many panels do you have, and be interested to know what inverter, and do you have a battery installed.

Bet your looking forward to a good summer like this year 🙂 

My Luxpowertek inverter also imports power from the grid every day. The average over the 3 months since it was installed is 0.26 KWh a day.

My neighbour, who has had solar pv with batteries for many years, warned me that the system would import from the grid when there was a sudden demand for power from the house while the batteries got up to speed ie because the batteries are slower to react than the equipment using the power.

Yesterday the system imported 0.2 KW hours in total, mostly when there was a spike in demand which exceeded the solar power being generated at that moment.  The demand was from the electric hob.

The system also imports small amounts from the grid for no reason that I can see, usually when the batteries are charging. Yesterday,  for example, it imported 109 watts when the data showed the system was generating 1796 watts, the batteries were 91% full,  the load was 177 watts and the charge going to the battery was 1691 watts. The load remained steady before and after. The readings for the power generated and the charge to the batteries, when it imported the 109 watts from the grid, were more than the equivalent readings before and after.

Is it something we have to live with, or can the inverter and battery technology solve the problem or does our domestic electrical equipment need rethinking to work in synch with solar PV systems?

So far (fingers crossed) the savings from my system far outweigh the cost of the imports.

Thanks @maryjay appreciate this I haven't had mine installed yet but will bear in mind what you have noticed on your system if it happens to me.

Hi @Jequinlan. New Solis system installed on Friday. I wonder if you would know why my system is exporting to the grid when the batteries are not full? 

Hi @downing123 I don't understand this myself but my Solis system is being installed in 2 weeks time so will look out and see if mine does like yours

It is worth noting that most (if not all) inverters do not react instantaneously and so if the sun disappears behind a cloud, there is a balance needed to control power from solar PV into/from batteries and to maintain supply from the grid - this is where there can be a feed back to the grid at time while the system is balancing. 
​​​As @Jequinlan mentions, these flows are normal but overall the system does what is required. 
I’m sure in future systems will be able to respond much faster on switchover. 

Another thing to consider is that batteries have a maximum charge rate. If your excess solar PV (over the amount being used by your house) is more than the maximum charge rate the excess will go to the grid, even though your battery isn't full.