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

Hi, I have a 3kw PV system that’s 8 years old which was using 3x basic inverters so have changed them out for an 8kw solis 5G and 2x Basen green 51.2v 100AH batteries in parallel and I’m at my wits end with it to be honest. The batteries don’t seem to communicate with each other to balance charge or load, once the batteries are getting low SOC the difference becomes too much for the inverter  and it gets muddled which one to read and what to do. I manually charged both batteries to 100% over the weekend and disconnected them from the inverter to let them balance voltages as per my suppliers instructions yet today one is down to 17% and the other 31% so the inverter wants to charge from the grid because of the 17% battery being below the 20% minimum SOC that’s setup but then it reads the SOC of the 2nd battery at 31% so switches from charging the battery to using the battery for a few seconds until it reads the 1st battery so reverts to charging again and round and round this cycle goes. 
 

My current desperate move is to remove the CAN link between the batteries so that the inverter only reads one of them but I’m worried that once the better weather comes round it might over charge the battery that doesn’t have a CAN link. 😭

Hi @Frazzled you need to be very careful with the charging of Li-ion batteries as they can become unstable. I’m assuming that your Solis inverter knows which batteries are connected (or similar) as most systems have a variety of parameters to chose from depending on their connections. 
There is also a primary battery to be designated when you have several connected. 
Do you have a schematic of the system perhaps?

Edit: I just found this battery compatibility list from Solis and I can’t see Basen listed https://www.ginlong.com/Uploads/file/Compatible_Battery_List_aus.pdf

I have them setup as battery 1 and battery 2, my supplier assured me they were compatible ☹️

My inverter isn’t on that compatibility list, I have an S5-EH1P6K-L, not an RHI inverter. 

Basen is still not listed on the Installation manual 

The actual reasons for this are both by design and by technical limitation, inverters are only allowed to ramp up and down at specific speeds, turning on a load in the house will draw some energy from the grid in most systems until the inverter has caught up, this could be 5-20 seconds in my expereance, and then, only up to its dc/ac inverters limit. It also needs to be able to shut down quickly if there is a power cut.

Re - the constant trickle, this will be both in and out to the grid all the time as the load fluctuates, the inverter only knows whats happening based on the CT clamp round the incoming live wire from the meter. Unfortunately these CT clamps are cheep and inaccurate devices at low currents. Look at your in home display and watch the live usage, you will see it moving through 100w export and 100w import all the time. 

Swapping out a ct clamp for a double pole meter like an estron connected to the inverter on modbus can get this trickle down to almost 0. This is a little more work so most installers dont bother and use the cheep ct clamp that comes with the inverter. CT clamp £20, meter £60. Cost to customer.. hundreds of pounds over the lifetime of the inverter.

This is an endemic problem of installers focusing on their profit rather than the customers return on investment.

Hi 

I’m new here and trying to find any advice to my solar issue which @downing123 did experience and maybe @davericho may have experienced.

3 phase Solis 6kw hybrid inverter, 6.6kw array and 3xFox HV2600 Batteries

3 Issues:

1. A constant low level ‘leak’ whenever solar is being produced, or no solar and just battery - eg on the app this morning Yield of 2.6kwh, Exported 1.16kwh, zero to battery BUT not significant enough to show on the Graph for ‘Power to Grid’. Consumption at all times today has been greater than yield (air source heat pump). I understand that low levels to the grid do happen but my net to the Grid has been 30% since December. Friday 20th Jan out of 10kwh yield 4.22kwh to the grid and batteries only hit 40%!! The sunnier the more I lose!?
2. Larger and recordable on the ‘Power to Grid’ Graph spikes to the Grid when batteries not even fully charged. Worst one was 1.489kwh to the grid when the battery chipped in 0.203kwh. Battery to grid has also spiked over 1kwh.
3. Batteries stop discharge at 20%

Yes I have an installer who is waiting to hear back from Solis which is taking an age but any comments would be helpful.

Thanks

Given your notes @Tomb2100 you may want to check your inverter settings. These can determine what priority is used in charging/supplying/feeding to grid and it sounds as if these might be not optimal for your system. 
Discharging of a battery system depends on the chemistry - a Li-Ion battery will normally have a 10% minimum level set as it is difficult to charge at very low levels. 
If you can check some of those parameters that might help

Hi /mbu198

Did you ever get a fix for this from Solis? I have the exact same issue with my Solis inverter and puredrive battery setup. It works out that whilst it only costs me 65p per day it’s pretty consistent and spread out over day and nighttime use this adds up over time and is quite annoying.  Thanks Jim

I have a similar annoing issue. I have a new PV 3.2 kwp system, with Solis S5-EH1P inverter, US3000 C battery from Pylontech , SDM-120CT meter coupled with an Eastron split core ESCT-TA16. When the system is not exporting energy to the grid, the meter of my energy provider shows an average input power of 50W, but the inverter and the app show 0w from the grid. It seems like an “error” from the clamp: is it possible or is it a normal behaviour of the inverter?
Thanks in advance for any suggestion!