Solar PV


The OpenEnergyMonitor Solar PV monitor is a tool to help you make the most of your solar generation.

Providing real-time and historic information on your solar generation and demand matching, it will help you make better use of available solar power.

MySolar PV is a dashboard app which runs on Emoncms.

SolarPV

Explore, visualise:

  • Solar PV generation
  • Site-consumption
  • Solar PV generation used on-site (self-site-consumption)
  • Solar PV generation exported to the grid
  • Electricity imported from the grid
  • Real-time & historic daily, monthly and annual totals

Contents

  1. Required Hardware
  2. Sensor Installation
  3. Emoncms Feed Setup
  4. Emoncms MySolarPV App

Required Hardware

See Solar PV tab of Setup > Required Hardware

The Emoncms setup instructions below are applicable to both the emonPi and the emonTx where CT1 is either site-consumption (Type 1 system) or import/export (Type 2 system) and CT2 is solar generation. If using an emonTx to monitor generation or site-consumption substitute the ‘log to feed’ instructions to use an input from the emonTx instead of emonPi (CT4 on the emontx a 0-4kW channel providing higher accuracy for this range and may be suitable for the solar CT if system capacity is less than 4kW).

Solar PV CT Install

It is important that an AC-AC adapter is used for both type 1 and type 2 solar PV systems. Without an AC-AC adapter the power reading can be significantly wrong - especially at night - due to the low power factor from some solar PV inverters. Further, at times an inverter might be consuming a small amount of grid power; without using an AC-AC adapter there would be no way to distinguish this consumption from generation and establish the true power flow direction.

Please read the CT installation guide before installing. Your safety is your responsibility. Clip-on current sensors are non-invasive and should not have direct contact with the AC mains. However, installing the sensors will require working in close proximity to cables carrying high voltage. As a precaution, we recommend ensuring the cables are fully isolated, i.e. power is switched off, prior to installing your sensors, and proceeding slowly with care. If you have any doubts, seek professional assistance.

The clip-on CT sensors must be clipped round either the live or Neutral AC wire. Not both.

CT sensor installation

emonPi Type 1 Solar PV

Type 1 solar PV System: When the generation and site-consumption can be monitored separately. The amount exported/imported to or from the grid is the difference between generation and site-consumption.

Type 1 system: Grid (import/export) = site-consumption – Generation

Type 2 solar PV System: When the generation and site-consumption cannot be monitored separately e.g. the PV inverter output is fed into the fuse box and the household loads are connected to other circuits in the same fuse box. If this is the case, the output from the PV inverter and the grid import/export connection will need to be monitored and site-consumption calculated by subtracting.

Type 2 system: Site-consumption = Generation + Grid import (negative when exporting)

The polarity of the power readings depends on the orientation of the clip-on CT sensor. Orientate the CTs so that generation and site-consumption is positive and grid import/export is positive when importing and negative when exporting. The correct orientation can be determined by trial and error.

For automatic MySolarPV App setup use the suggested feed names mendtioned below in bold. These names are case sensitive.

The following assumes:

  • CT1 (power 1) = site consumption.
  • CT2 (power 2) = solar generation.

1. Setup site-consumption Feed

  1. Click on spanner icon to configure emonPi/power1.
  2. Add the following process steps under Add process:
    1. Log to feed, called use, with feed engine PHPFINA, at 10s interval.
    2. Power to kWh, called use_kwh, with feed engine PHPFINA, at 10s interval.
    3. - input, choosing power2:. This will subtract the solar generation from the current value, giving us what’s being imported.
    4. Allow positive. This will allow only positive values to pass, since import is only if this number is positive.
    5. Log to feed, called import, with feed engine PHPFINA, at 10s interval.
    6. Power to kWh, called import_kwh, with feed engine PHPFINA, at 10s interval.

2. Setup Solar PV Generation Feed

  1. Click on spanner icon to configure emonPi/power2.
  2. Add the following process steps under Add process:
    1. Log to feed, called solar, with feed engine PHPFINA, at 10s interval.
    2. Power to kWh, called solar_kwh, with feed engine PHPFINA, at 10s interval.

Once complete click on Apps > MySolarPV in order to launch the MySolarPV Emoncms app, If you decide to use custom feed names the app will give you the option to select your solar, use and import feeds.

For automatic MySolarPV App setup use the suggested feed names mendtioned below in bold. These names are case sensitive.

The following assumes:

  • CT1 (power 1) = grid import (positive) / export (negative).
  • CT2 (power 2) = solar generation.

1. Setup Grid Import Feed

  1. Click on spanner icon to configure emonPi/power1
  2. Add the following process steps under Add process:
    1. Allow positive. This will isolate only import.
    2. Log to feed, called import, with feed engine PHPFINA, at 10s interval.
    3. Power to kWh, called import_kwh, with feed engine PHPFINA, at 10s interval.

2. Setup Solar Generation Feed

  1. Click on spanner icon to configure emonPi/power2
  2. Add the following process steps under Add process:
    1. Log to feed, called solar, with feed engine PHPFINA, at 10s interval.
    2. Power to kWh, called solar_kwh, with feed engine PHPFINA, at 10s interval.
    3. + input, choosing power1:. This adds grid import/export to the solar generation, to calculate site consumption.
    4. Log to feed, called use, with feed engine PHPFINA, at 10s interval.
    5. Power to kWh, called use_kwh, with feed engine PHPFINA, at 10s interval.

With your emonPi or emonTx inputs configured as above and with use of the suggested feed names the MySolarPV app will launch with no further configuration required.

Alternatively the MySolar app will automatically show the configuration screen if it can’t detect the expected feeds. It’s then possible to select feeds from the drop down feed selector menus:

Once the required feeds are selected, the Launch App button will appear.

my-solarpv-config

The main view shows a moving window power view of solar generation Vs site-consumption which, can be used to explore matching at any given moment of the day. Site-consumption is shown in blue and solar generation in yellow. The totals at the bottom of the page relate to the current window selected and show at a glance how much of site-consumption was supplied directly from solar and how much of the solar generation was exported to the grid.

my-solarpv-config2

Clicking on view history brings up a bar graph showing solar generation and site-consumption on a daily basis. Including how much of the solar generation is used directly on site and how much is exported.

my-solarpv-config3