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

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Hi @Mbu1982 

 

Welcome and I hope below answers your question:

 

Yes the PV systems all draw (at times) an amount from the grid.

 

I have been monitoring mine for weeks and can confirm there are times there is :

 

A) a trickle from the grid, a cloud can drop PV suddenly and if charging a battery the grid may step up while the battery charge is adjusted

B) a trickle TO the grid, this happens most when PV panels suddenly gain more sun, or when battery is charged.

C) when the battery falls to 4% on my system the trickle to the grid is used to maintain the management of the PV system.

 

Pretty sure the net benefit of solar far exceeds this gain/loss scenario but it appears to be just the way it is.

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.

T
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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

BPLightlog
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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

Independent volunteer - Sitting in a Faraday cage, waiting for a signal
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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

F
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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!

BPLightlog
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Userlevel 7
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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!

Hi @fabiodifa , the meter readings from your provider (smart meter?) will be more accurate. The clamp monitor is a general guide but not as accurate. These type of systems also tends to give an update every few minutes so can give false readings every so often. 
There are a couple of things to consider. 
The settings on your inverter which might look at a charge state overnight and

Switching routines which at low input levels from the solar and battery system can cause grid demand as they don’t switch as fast as the demand changes 

Independent volunteer - Sitting in a Faraday cage, waiting for a signal
F
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Hi @fabiodifa , the meter readings from your provider (smart meter?) will be more accurate. The clamp monitor is a general guide but not as accurate. These type of systems also tends to give an update every few minutes so can give false readings every so often. 
There are a couple of things to consider. 
The settings on your inverter which might look at a charge state overnight and

Switching routines which at low input levels from the solar and battery system can cause grid demand as they don’t switch as fast as the demand changes 

 

First of all, thanks for your reply. It seems like an "offset" related to low power consumption, so I think I can't solve it!

BPLightlog
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You may be correct @fabiodifa. Your monitoring system and inverter will be taking its feed from the clamp so anything you can do to correct that would help overall. I know that several providers have updated their systems over the last few months so just ensure that you have the latest version (I’m sure you do) and the position of the clamp might be significant as well

Independent volunteer - Sitting in a Faraday cage, waiting for a signal
C
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I have similar situation with my Sunsynk system the grid seems to supply up to about 20% of my power use rather than draw from full batteries, whatever the load requirement is, But not all the time! Usually runs at about .05 Wfrom grid. 
I also notice that the energy supplied by solar panels , battery or grid seems to add up to about 20% more than the power required! Is this normal? 

 

BPLightlog
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Hi @Coypu , most systems do have a need to still draw from the grid. Sometimes it depends on how the system has been set up. There will also be times when the solar production will drop due to clouds or suchlike and it can take a while for the battery to switch in. 
Inverters have their own system monitoring to detect and measure power flow but they are not as accurate and so can give differences in value. 
You might be able to adjust a few things if you thought it useful .. but it needs care when changing settings

Independent volunteer - Sitting in a Faraday cage, waiting for a signal

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