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PV Importing Not Decreasing as expected

Aron Wyn Jones

Im an electrical supervisor at a manufacturing plant. We installed a 1MW PV system to our roof, which has been a good success in generating power.

But we noticed through the year, as weather is improving during summer our generation increase, but our imported power from the grid tends to remaim the same. We were expecting the imported power to fall as the generated power increases.

Nothing has changed at the plant. Yes, product tonnage various but not much. Our energy KPI are being affected. 

We have checked our 7 PV inverters metering against our utility class calibrated Fluke 1777 power quality analyser, and all 7 are accurate.

Our factory power set up is as follows. We receive x2 11kV feeds from the grid which is ran around our x3 switchrooms (11kV ring main). Out of the x3 switchroom, we have x7 11kV to 400V transformers, and through one of these LV boards our PV system is connected to.

Is there anything we are missing here? As i said we generating good amounts of electricity, so from Janurary commissioning to August we've generated around 900MW of power.

Parents

  • I have to ask...

    If you have two separate 11kV feeds from the grid, has someone managed to set it up so that all the big loads are on one feed, while the export is on the other?

    1MWp will only deliver 1MW if it's a sunny day and the sun is directly over the panels.  Not necessarily midday GMT; it will depend on which way the panels are pointing.

    If it's cloudy, expect a lot less.  At the wrong time of day, you will also get less.

    If your usage is so high that you never export, then maybe the generation is so small you don't notice it when aggregated on daily basis.

Reply

  • I have to ask...

    If you have two separate 11kV feeds from the grid, has someone managed to set it up so that all the big loads are on one feed, while the export is on the other?

    1MWp will only deliver 1MW if it's a sunny day and the sun is directly over the panels.  Not necessarily midday GMT; it will depend on which way the panels are pointing.

    If it's cloudy, expect a lot less.  At the wrong time of day, you will also get less.

    If your usage is so high that you never export, then maybe the generation is so small you don't notice it when aggregated on daily basis.

Children
  • in reply to Simon Barker

    We were exporting (which we didnt want this to happen) so we moved the 11kV 'normal open point' so that x2 out of 3 of our switchroom were now absorbing the PV generation rather than 1 before. Afterwards, we stopped exporting. So we sorted that issue out. We were expecting for the imported kWh to decrease as PV increased (kWh) throughout the year. But its not the case. Same loading.

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