10kw-solar

Solar Energy Self Consumption

I recently moved into a house that was consuming 85 kWh a day through winter. Ouch. I’m working to reduce it but realistically dropping it below half of that might be hard. Philosophically and economically irrationally I want my home to be a net zero consumer of electricity. If I can’t achieve this on a daily or weekly basis then I’ll settle for an annual basis.

Our peak loads will most certainly be in winter when solar irradiation is at it’s minimum, this is our constraint. I installed 10kW of panels and a 10kW inverter to start with. I might over panel it in future.

Thinking about all of the above, and granted storage is rapidly becoming more feasible, maximising self consumption of power from residential solar is going to play an important role in minimising the use of fossil fuel generated electricity.

This blog post is my experience of figuring out how to do this.

Generation

Solar system comprises of:

  • 36 x Hanwha Q.Cells Gmbh Q.Peak 280W mono modules
  • 18 x TIGO Dual Maximisers with independent panel tracking
  •   1 x TIGO Single Maximiser
  •   3 x TIGO rooftop gateways
  •   1 x TIGO MMU or inverter datacard
  •   1 x Fronius 10.0kw SYMO 3P Austrian Made PV inverter
  •   4 x IMO DC isolators

Demand

  • When excess power is available, divert power in order of priority to:
    • Heat pump hot water 1-2 kWh/day
    • Electric car charger, if connected, typically needs ~10 kWh/day
    • Pool pump, requires 3/6 kWh/day (winter/summer), ideally run in the middle of the day.
    • Storage (if installed in future)
    • Air conditioner – during winter and summer only.
      • Unit 1: SRD20E : 6.18 kW
        • Winter use normally 6+ hours per day.
      • Unit 2: TBC seldom used.
  • The total demand from the rest of the home is unknown at the moment due to significant recent changes. I’m expecting/hoping it will settle at around 10 kWh per day.

research:

CHANGES MADE:

  • Installed a Fronius Smart Meter, this provides a data feed of power consumption which the inverter uploads to PVOutput.org along with solar energy production data.
    Screen Shot 2016-08-16 at 3.12.13 PM
  • Using the above data from the smart meter I can see that the majority of the time the solar produces enough power to cover the pool pump. I’ve scheduled the pool to run between 10am and 2pm in winter and will extend beyond this in summer.
  • Hot water system was changed to a Sanden Heat Pump and has been scheduled to start at 11am each day, typically running for around 2 hours at 1kW load.
  • The above two are rudimentary scheduling changes, there are days when solar output is insufficient to cover the load but for the most part it does.

References & Resources:

This post is an ongoing work in progress – check back for updates.

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