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Solar Produced vs Home Consumed

 
Solar Photovoltaic (PV)
Last Post by JamesPa 43 minutes ago
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 WesleyP1874
(@wesleyp1874)
Active Member Member
Joined: 1 year ago
Posts: 18
Topic starter 26/05/2026 11:06 am   [#3021]

Hello can anybody advise please..this may be a silly question as I'm not familiar with the workings of the inverter.  We have 11 panels installed avout 4.84kw)  S Solax X1-Boost-G4 invertor.  No Battery.  No contract to sell back into the grid.  I use the Solax Cloud app to monitor performance.  On a good day I might get about 18kw solar output.  The app also tells me that the domestic consumption is exactly the same.  Does this simply mean that every bit of solar power produced has been used in our house?  On a bad day the Solar Output is way down but according to the app so is domestic consumption.  Does the inverter juggle between power sources and prioritise solar power use over electricity from the grid?  



   
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JamesPa
 JamesPa
(@jamespa)
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Joined: 3 years ago
Posts: 4916
26/05/2026 11:18 am  

Posted by: @wesleyp1874
↑

Hello can anybody advise please..this may be a silly question as I'm not familiar with the workings of the inverter.  We have 11 panels installed avout 4.84kw)  S Solax X1-Boost-G4 invertor.  No Battery.  No contract to sell back into the grid.  I use the Solax Cloud app to monitor performance.  On a good day I might get about 18kw solar output.  The app also tells me that the domestic consumption is exactly the same.  Does this simply mean that every bit of solar power produced has been used in our house?  On a bad day the Solar Output is way down but according to the app so is domestic consumption.  Does the inverter juggle between power sources and prioritise solar power use over electricity from the grid?  

All inverters will use solar power in preference to drawing power from the grid.  If the available power is insufficient, power will be drawn from the grid.  This is 'real time' so if the sun goes behind a cloud and you are boiling the kettle, the power comes from the grid if you dont have a battery.

When there is excess solar power the behaviour depends on the inverter.  The most common set up is that they will export to the grid up to a maximum of 3.68kW, this will occur whether or not you get paid for the export.  However they can be set up to export none, or a greater amount (which requires permission from your DNO).

Not sure what solax cloud does but you need to distinguish between kWh (energy) and kW (instantaneous power - ie rate of use of energy).  Your panels may well generate 18kWh over the day, but only a proportion of this will get used locally because, if the instantaneous demand from the house (kW) does not exactly match the instantaneous production from the panels (kW) then either grid import or export will occur,  How Solax reports this I do not know.

Without a battery (and even with one) you will usually generate in summer a lot more than you can consume, you can get paid for this and its madness not to.  Typically self-consumption is about 40-60% averaged over the year.  With a 4.84kW peak array you should be generating about 4000kWh annually, so you will be exporting 2000kWh.   Octopus for example will pay 12p/kWh so thats roughly £240 per year you are missing out on.     

 

Hope that helps. 

 


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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