GROWATT & SOLAR ASSISTANT

Growatt Solar System Wiring & Operation Using SolarAssistant

This site is designed as a technical reference for myself & also a guide for someone considering using SolarAssistant with a similar setup.

SolarAssistant is software used to monitor and control your solar system in real time and can be purchased from the SolarAssistant site.

It is designed to run on a Raspberry Pi that is plugged into the solar inverter and optionally a battery.

The application can be accessed from a web browser or the Android/iPhone app via local network or the internet.

Note at present SolarAssistant does not sysc the inverter clock so the Growatt dongle needs to remain in place.

SolarAssistant

Features

Real-time analytics via Web, Android and iPhone.

Metrics are live up to 2 seconds. SolarAssistant is a standalone system that can be used without the internet.

However when you are away from home all features are available remotely via the internet.

Real-time metrics makes all the difference and gives true insight into how your system performs.

Instant updates are really convenient if your trying different settings to see how it affects your system.

10+ Years of historical data via interactive charts

SolarAssistant puts you in control of your data by storing it on your device instead of a cloud service.

SolarAssistant running on a Chromebook

SolarAssistant runs on any device using an app or web browser.

SolarAssistantOverview

My SolarAssistant uses a Raspberry Pi 3+ mounted in a metal case and is positioned near my Growatt SPH5000 inverter.

The metal case also acts as a heatsink so no other cooling is required.

I have run a LAN cable direct to the raspberry Pi as the WIFI signal is poor at that location.

SolarAssistant's Raspberry Pi 3+ mounted in a metal case

Growatt Dongle

If required you can still connect the Growatt dongle and configure your inverter via the Growatt servers and also use the ShinePhone app on your mobile device.

I have both connected and they work alongside each other.

My System Layout and Specifications

There are 14 Trina Solar Vertex 405 panels on my ESE facing roof.

I have a Growatt SPH5000 inverter that has an a/c rated output of 5kW.

My battery is a Growatt GBLI6532 with 6.5kWH capacity.

I have EPS (emergency power supply) supplying a few sockets in the house.

My dual element immersion heater is connected to a Solar iBoost+ for hot water heating by Solar.

I have a chrome book mounted near the inverter which is used for setting up and monitoring via SolarAssistant and or the Growatt Server.

The solar system is located in my garage with a rough layout as below.

Growatt System

SPH5000 Inverter

The Growatt SPH Series is used to store energy generated by the photovoltaic cell panels
or energy from grid if it is allowed in the battery, also energy can be sent to power
grid through the SPH for self consumption or when Grid power is lost, the SPH can be used as
back up power.

GBL6532 6.5kWh Battery

The Growatt GBLI6532 is a lithium battery with a capacity of 6.5kWh. The battery utilises LiFePO4 technology, which offers a range of benefits, including: improved discharge and charging efficiency, longer lifespan, increased safety and lightweight design.

The battery can be paired with a twin unit to offer a maximum capacity of 13kWh. The unit is easy to install and can be wall mounted or floor standing.

Extras

Solar iBoost

Solar iBoost+ is installed next to the hot water tank and receives messages from the Sender unit clamped to the main feed off the incoming main.

When activated, it intelligently controls and adjusts the level of energy flowing to your immersion heater in line with the export levels as they rise and fall.

iBoost Buddy

iBoost+ Buddy is the wireless home energy monitor and remote control for the Solar iBoost+

The eco-gauge lets you know when unused energy is available so you can switch on appliances.

It has the same buttons and functions as the main unit and can be situated anywhere in your house.

SolarAssistant Connections

Download and install a copy of SolarAssistant and install it on your Raspberry Pi following the instructions on the site.

I have installed SolarAssistant onto a Raspberry Pi 3+ and mounted it into a metal case from Amazon.

The connection to the Growatt inverter is via a USB to RS485 Converter with CP2102 Chip.

I found the converters with the cheaper CH340 chip did not work with my inverter.

Com Port Connection

View from the underside of the inverter showing the location of the com port I used in red.  The port is labeled RS485 on my inverter but the diagrams from Growatt show it as 485-2.

I used a standard RJ45 cable and cut one end off and then connected the Blue and White/Blue wires to A+ and B- of the USB to RS485 converter.

Pin connection chart for the SPH Inverter

I found Pin 4 Blue & Pin 5 White/Blue worked on my inverter.

The USB to RS485 converter is plugged into a SolarAssistant USB Port.

On the inverter navigate to the RS485 menu and set it to VPP mode.

On the SolarAssistant configuration page the converter should now be visible.

Click "Connect" to start using the data from your inverter.

The status should change to "Connected"

Schematics

SolarAssistant Connections

SolarAssistant is powered from a 5v Raspberry Pi PSU plugged into a wall socket off the standard ring main in my garage.

A USB to RS485 CP2102 converter plugs into a USB port and the A+ & B- outputs are connected to pins 4&5 of a RJ45 plug.

The RJ45 plug is connected to the top right socket on the inverter marked RJ45. This is socket 485-2 shown on the diagrams from the inverter manual.

A standard RJ45 to RJ45 network cable then connects to my internet router (you can also use WIFI if your router is in range).

Once connection is established your SolarAssistant will be accessible on your home network as well as anywhere in the world via the internet.

Note the inverter comes with a WIFI Dongle so you can connect to the Growatt servers. This  allows you to store your data and control/monitor your solar system.

This will work alongside SolarAssistant if required.

Growatt System on the Growatt servers.

Solar System Main Wiring

Inverter Lower Panel layout

Growatt SPH Inverter Priority Modes

There are three priority modes for a SPH series inverter Load First, Grid First, and Battery First to meet different operational scenarios.

Load First

Load first is the default mode, when it's working in this mode, PV energy would be used for the load and then battery.

When PV is Insufficient the battery discharges.

When PV is sufficient for the load  the excess energy is used to charge the battery. If there is no battery or battery is full, the excess energy is exported to the Grid.

When solar power is insufficient and lower than load power, the battery will be discharged automatically and support the load along with solar power.

If the battery discharges to the discharge-stop SOC*, it will stop, then the solar and grid will support the load.

When solar power is off and therefore lower than load power, the battery will be discharged automatically and support the load.

If the battery discharges to the discharge-stop SOC*, it will stop, then the solar and grid will support the load.

Note:The “Discharge Stop SOC” is available for setting.
*The battery power supply can be restored when the battery is charged to the value of “Discharge-stop SOC +3%” by solar

Battery First

When SPH inverter is working in this mode the battery would be charged first, and is suitable for use when the when the electric import charge is low.

The user needs to set the mode ON and OFF time, and the end time of battery SOC.

Users can set power rate which is less than the battery maximum output power.

If the customer doesn't enable the AC CHG (AC grid charging functions) the Inverter will charge battery by PV power as much as is possible up to the "Charge Stop SOC" in the config.

If the customer enables the AC CHG (AC grid charging functions) the Inverter will charge battery by PV power and AC power from the grid as much as is possible up to the "Charge Stop SOC" in the config.

For multi-step electricity price tariffs , the SPH inverter can store the power into the battery when the electricity price is in the off-peak rate and use the power in peak rate time or save the energy for blackout.

When the solar is sufficient, solar will charge the battery at top priority, and the surplus solar power will support the loads with the grid.

When the solar is insufficient, the solar will charge the battery at top priority, while the load will be powered by the grid.

If you enable the AC Charge function, the grid will not only support the load but also charge the battery together with solar power until battery reaches “Charge Stopped SOC”.

Note:The “Battery Charge Power Rate”, “Charge Stopped SOC” “AC Charge Function” and “Charge Period” are available for setting.
Please do set the “Charge Period” otherwise the operation modes will be adjusted to “Load First” automatically.

When the solar is off the load will be powered by the grid.

If you enable the AC Charge function, the grid will not only support the load but also charge the battery together with solar power until battery reaches “Charge Stopped SOC”.

Note:The “Battery Charge Power Rate”, “Charge Stopped SOC” “AC Charge Function” and “Charge Period” are available for setting.
Please do set the “Charge Period” otherwise the operation modes will be adjusted to “Load First” automatically.

Grid First

 When SPH working in Grid-first mode, the PV energy would export to the Grid first. This can be used during the period when the electric import charge is at it's highest.

User need to set the mode ON and OFF time, and the end time of battery SOC.

User can set power rate which less than the battery maximum output power.

When solar power is sufficient, the solar power will supply the max. AC power output to the load and the grid, then the surplus solar power will charge the battery.

When solar power is insufficient, the solar and battery will work together to ensure the max. AC power output, supply power to the load and export power to the grid.

The “Battery Discharge Power Rate”, “Discharge Stopped SOC” and “Discharge Period” are available for setting.

The “Discharge Period” must be set otherwise the operation modes will be adjusted to “Load First” automatically.

When solar power is off, the battery will work  to ensure the max. AC power output, supply power to the load and export power to the grid.

The “Battery Discharge Power Rate”, “Discharge Stopped SOC” and “Discharge Period” are available for setting.

The “Discharge Period” must be set otherwise the operation modes will be adjusted to “Load First” automatically.

Custom Settings

Depending on your energy tariff you will want to adjust your battery use to make the most of cheap rates.

The chart below show the current Flux tariff from Octopus energy.

Between 02:00 & 05:00 the import rate is set to 18.54p/kWh rather than the normal rate of 30.9p/kWh and the peek rate of 43.26p/kWh.

I use this period to heat my hot water (timer setting on my iBoost), top up my battery (using "battery first" priority mode on the inverter) and turn on the dish washer/washing machine.

I try to keep my batteries with enough power to cope during the peek period from 16:00 to 19:00 hrs.

On SolarAssistant the settings can be found in the "Configuration" tab inder "Inverter".

Click on "Settings"

Clicking "Settings" opens the configuration window.

You will need to adjust the "Priority settings" and also the "Priority schedule"

Go to the "Priority schedule"  and click "edit".

Set the time you want the battery to stop discharging and get a charge if below a set level.

This is set to match the Octopus cheap tarrif time 02:00 to 05:00hrs.

Tick the enable box and then click save.

Go to the "Priority settings" and click "edit".

Set the "Battery first grid charge" to "Enabled"

Set the "Battery first stop charge" to 30%.

This will keep the battery at 30% charge until 05:00 when it will start to discharge again if required.

The % charge level may need to be adjusted up as the days get shorter in winter.

Note a 2nd charge "Battery first slot 2" may be required to get through the high tarriff rate from 16:00 to 19:00 if there is not much solar charge on a dull winter day.

Growatt Custom Settings

To change the same settings on the Growatt sever go to the server and log in.

On the main dashboard window scroll down to "My Photovoltaic Devices"  and click "Setting" on the right.

On the popup window scroll down to "Battery First"

Set the "Charge Stopped Soc" to level of charge you require.

If you want the battery to be charged off the grid (it's cheap rate so I do) set "AC  Charge" to ON.

Set "Time Slot 1" to the cheap rate times of your tariff to in my case 02:00 to 05:00hrs.

Save the settings by entering todays password in "Please Enter Key To Save" box and then click "Yes"

The Growatt Key changes daily and is todays date in US formay eg YYYYMMDD.

Days overview chart showing power from Grid,PV, Load and also the priority mode of the inverter

Between 07:00 and 16:00 this is day rate. In the summer the inverter is set to "Load first" during this period.

In winter where solar power is limited there is a short period from 15:00 to 16:00 where the inverter is set to load first. The charge level is set to charge the batt only if it falls below a set charge level.

The charge level set is enough to get through the 3 hour peak period from 16:00 to 19:00.

Peak Rate

The chart below shows the peak rate period where the electricity import and export cost is at it's max.

The "Priority Settings" on the inverter is set to "Load First" during this period.

In an ideal world the Red line (Grid) on the chart should be on 0watts or - ve watts (exporting).

The max output from the battery is 3kWh so as long as the battery has charge and less than 3kWh load is switched on no power will be taken from the grid.

In summer months there is also some residual PV power from my ESE facing panels to also give some extra power at least for a few hours in this period (yellow line) and also export to the grid (red line).

The chart shows a 4.1kWh load peak at about 18:10 where the batt combined with solar power could not keep up with demand and 1kW power from the grid was consumed for a few minutes.

Peak Rate Winter

The chart below shows the peak rate period where the electricity import and export cost is at it's max.

The "Priority Settings" on the inverter is set to "Load First" during this period.

In an ideal world the Red line (Grid) on the chart should be on 0watts or - ve watts (exporting).

The max output from the battery is 3kWh so as long as the battery has charge and less than 3kWh load is switched on no power will be taken from the grid.

In winter months there is very little residual PV power from my ESE facing panels.

At 15:00 to 16:00 the inverter switches to "Batt First" and the battery will be topped up to a set charge level with enough stored power to get through the peak period.

The chart shows a 4.1kWh load peak at about 18:10 where the batt could not keep up with demand and 1kW power from the grid was consumed for a few minutes.

Cheap Rate

The chart below shows the cheap rate period where the electricity import and export cost is at it's max.

Using the "Priority Settings" and "Priority Schedule" on SolarAssistant the inverter is set to "Battery First" from 02:00 to 05:00.

During this period if the battery falls below a set charge level it will boosted to maintain it's charge at this set level until 05:00.

This allows the battery to maintain the load after 05:00 once the day rate begins until power from the panel kicks in early morning from my ESE facing panels.

The first peak in the chart is the batteries being boosted for 30mins.

The second peak in the chart is the iBoost Water heater kicking in to heat my hot water from 04:00 to 05:00.

The short spike at 04:30 is from the kettle going on for a cup of tea.

Once this 3 hour period is over the inverter switches to "Load First".

Solar iBoost+

The Solar iBoost+ is designed to be used in conjunction with micro-generation systems,
e.g. solar PV, where surplus energy generated can be stored within a domestic hot water
cylinder in the form of hot water.

By monitoring the amount of energy being exported to
the National Grid the Solar iBoost+ unit will divert energy into an immersion heater when
the energy generated exceeds the amount of energy consumed within the property. Solar
iBoost+ controls the energy delivered to the immersion heater in proportion to that
exported.

Solar iBoost Wiring

Refer to the main schematic below

and the manufacturers diagrams below.

Dual Immersion Heater Operation
The Solar iBoost+ automatically detects when two immersion heaters are connected.
As hot water is drawn from the upper part of the tank, it is important the heaters are
connected as shown so that the Solar iBoost+ can automatically give heating priority to
the top heater. Excess generation is diverted to the top heater until temperature is
reached and the heater thermostat opens. Solar iBoost+ then automatically switches to
the lower heater to continue to divert excess generation until the lower heater is also
satisfied and ‘Water Tank HOT’ is displayed.
When diverting to the lower heater the Solar iBoost+ will periodically (every 15 minutes)
switch to the top heater and the cycle of heating begins again. This maintains the
temperature in the upper part of the tank.
An indication of the current heater being supplied is shown on the ‘Heating by Solar’
display, see page 13.
This operating mode is the same whether diverting excess generation or in boost function.

iBoost Settings

Setup iBoost to heat water during cheap rate 02:00hrs to 05:00hrs

My tariff lets me heat water at 18.54p between 02:00hrs and 05:00hrs.

I get 19.9p to export excess solar power outside these times so including a bit of inefficiency I should get back any spare power by exporting extra during the day.

Timed Boost periods can be entered against Summer and Winter seasons. This enables longer boost times to
be set in Winter periods when solar generation maybe less. Two boost periods are available each day and can
be programmed on a 5 day weekday/2 day weekend basis. Start times are selectable in 15 minute steps and the duration of the
boost in 30 minute steps. e.g. a setting of 04:00 1hrs will switch on the boost at 4 am for 1 hour.

An unused boost is left at 00:00 for 0:00 duration. The operating boost season is set manually using the
Boost Season feature found at the end of the normal Display Cycle.

Boosts may be temporarily disabled (e.g. for holiday periods) by selecting ‘Timed Boosts OFF’.

I don't use Winter and summer boost setting but have added identical winter settings just in case.

Changing Summer/Winter setting and turning timed boost On & Off

These settings can also be carried out on the optional iBoost Buddy display

 Emergency Power Supply EPS Setup

To ensure the safety of Power Network engineers in a power cut the solar system must be disconnected from the grid.

The Growatt SPH has built in EPS so you can run off battery power if the grid fails.

EPS is fed out of a separate 3 pin socket on base of the Inverter.

EPS must be enabled before it will work.

On SolarAssistant the settings can be found in the "Configuration" tab inder "Inverter".

Click on "Settings"

In SolarAssistant go to the "Grid and backup settings" section and make sure "Backup UPS" says "Enabled" 

Winter Settings

In December and January there is not enough solar energy to make the battery last all day from it's cheap rate overnight charge.

I need to top it up on standard rate electricity so I don't pay for peak rate between 16:00 and 19:00 hrs.

I found if I top the battery up to 60% it will get me through to the next cheap rate charge.

Once charged after 16:00 I need to set the settings back to 100% charge and disable slot 2 so it charges correctly overnight.

To change the same settings on the Growatt sever go to the server and log in.

On the main dashboard window scroll down to "My Photovoltaic Devices"  and click "Setting" on the right.

On the popup window scroll down to "Set EPS On/Off"

Make sure it is set to "On". 

If you had to change the setting to "On" save the changes by entering todays password in "Please Enter Key To Save" box and then click "Yes"

The Growatt Key changes daily and is todays date in US formay eg YYYYMMDD.

EPS Wiring

Growatt provide wiring diagrams for the EPS output for the SPH inverter range.

Click image for larger version

Diagram A uses a Growatt ATS switch.

The Growatt ATS-S (Auto Transfer Switch Single Phase) controls the switching of the contactors to provide power to the EPS load in both grid-tied and off-grid conditions.

The ATS-S integrates a contactor to provide users with a simple connection. It is used with Growatt Hybrid inverter and AC coupled inverter (single phase).

Configured with ATS-S, when the power outage, ATS-S can automatically switch to Off-Grid state, it can continue to supply power to the EPS load, the load can continue to run.

Growatt ATS

Growatt ATS wiring schematic. 

After speaking with my solar installer I decided to go with a manual switch  instead of the Growatt ATS or AC relay.

The manual switch feeds the EPS load via a small RCD protected consumer unit.

The consumer unit feeds 4 double sockets marked "EMERGENCY POWER SUPPLY".

I have 2 double sockets in my garage 1 by the Inverter and 1 by the boiler (so I can power my boiler during power cuts) and also a double socket in the kitchen and one in the lounge.

If I get a power cut I just need to switch the EPS switch in the garage then plug in what I need in an emergency into the sockets.

System Schematic including manual EPS

click image to enlarge

EPS Earthing

In order to use the EPS safely a Earth must be provided at the house. I have a TN-S power supply to my house that has a braided earth connection off the network power cable.

In the event of a network cable fault or engineers working in the network causing a causing a blackout the power cable earth may become disconnected leaving your house without an Earth.

The usual way of providing an earth at the house is to install an earth rod but due to many services in the vicinity of the earth location I decided to use a  Condudisc Earth  video here .

Condudisc

Installation of the Condudisc requires digging a 900mm (3ft) deep hole.

When the earth was tested it measured 59Ω which compare very well with the maximum allowance of 200Ω.

Local Control & Monitoring

My solar system is located far from the WIFI in my house and mobile signal reception is very poor.

I have purchased a 2nd hand Chrome book and mounted it below the inverter to use as a system monitor/controller.

Chromebooks power up in seconds and are very cheap.

I used a Acer Foldable 2-in-1 Chromebook R11 C738T-C7KD 11.6 inch screen and it cost £70 on ebay 2nd hand inc a 2 year warranty.

The chrome book is foldable so works as a tablet and has a touchscreen.

I used the LAN cable from the SolarAssistant  split with a powered RJ45 cable splitter and then a RJ45 to USB ethernet adaptor to connect to the chrome book USB port.

chrome book LAN cable connection

The Chromebook has been folded flat and sits between the inverter and battery.