ES-Mini comes in two variants.
1) ES-Mini-2000 (opt. backup )
Panels
The solution consists of solar panels which can produce up to 3000Wp and which do not exceed 500V voltage when connected in series. This could be six (minimum: four) modern 450W or even 500W panels. It could also be 9 or 10 older panels (e.g. 320W each).
Inverter
The inverter MIC-2000TL-X is a classical string inverter with only one power point tracker. It is very cheap (probably ~150€). For configuration and monitoring one must add a Shine-Link-X stick (20€).
If you connect the inverter to the panel string and to your home grid (single phase, 16A) you will have a solution which simply feeds all of the solar energy it can harvest into your local home grid.
If you add a smart meter you can control the amount of backfeed into the grid.
Here is a link to the manual for the inverter and for the shine link-x
Installation material
You will need an AC cable and two DC cables with 4 MC4 connectors.
We recommend to mount the inverter inside the building which means that you need only two long DC wires (e.g. 15m) and the AC wire will be short.
But it is also possible to place the inverter outside close to the panels which would mean that you have no additional DC cable but a longer AC cable.
You need mounting material for the panels depending on your roof’s conditions. Keep in mind that you should avoid a situation where shadows of trees or other buildings move over the panel surface. A low angle (10 degrees or so) with half of the panels facing East and the other half facing West will spread the energy flow over the day more or less evenly. For maximum power gain you could use a steeper angle and southern orientation. But depending on how much energy you need (and when you need it) this may lead to excess energy wich you (hopefully) can feed into the official grid (probably without financial compensation). A southern orientation and an angle of 25 degrees may make sense if you add a backup storage solution (UPS) to your system.
Backup Solution
A UPS solution like the Fossibot F1200 (400€ with voucher) could help you to bridge periods where the public grid is not available. It has the additional advantage that it is portable. It can be placed anywhere in your house, typically close to the devices for which you want to provide emergency power in case of grid failure.
The primary focus of such a system is protection against fault. This means that it is connected to the grid permanently and it will discharge its battery only if the grid power goes away. The switching process is automatic and happens within some milliseconds.
An additional use case, however, could be to discharge the battery when the sunlight disappears. This will optimize your energy cost but of course it will put you at the risk that you have no electricity if the grid fails at a moment where the battery has been fully discharged.
UPS systems do not know how much energy your house currently needs or how much solar energy is being harvested at the moment. But with a bit of attention you can use the UPS to help you in saving energy cost.
Here is a link to the Fossibot manual.
Smart Meter
A smart meter like the SDM630 (60€) can be installed in your grid box if you are required to avoid feeding energy back into the grid. The smart meter must be connected via a thin RS485 cable to the inverter.
Here is a link to the manual.
If you must control backfeed a smart meter is necessary. Otherwise not.
In Ukraine most households have a master switch in the grid box, sitting next to the officicial energy meter. This makes it fairly easy to install a smart meter because you can switch off electric power easily during the installation of the smart meter. Of course you must really know what you are doing if you are attempting to change something within your grid box. Otherwise you must find someone who knows how to do it and who works on a professional level with electricity.
Phase Equalization
There is another point which is important when considering backflow resp. the use of your own energy: PHASE assignment of source and drain. You have three AC phases in your house (with a phase shift of 120° between them) and the electric loads are connected more or less randomly to one of the three phases. If you connect a PV system to phase 1 and if your loads take the same amount of energy from phase 3 (for example) then the NET BALANCE of your household will be ZERO. But technically speaking the electric current on phase 1 will flow into the grid and a flow of equal size will be imported on phase 3. Typically the energy meter of your provider calculates the sum of the energy flows over all three phases and the number it shows reflects the SUM of the three flows.
Therefore it is not necessary to connect the ES-system to a specific phase.
Should you really have a meter which does no balance out phase differences when calculating energy consumption phase assigment would be an issue. In case of doubt ask an electrician or your grid provider.
Reading SML signals via infrared
If you have a modern bi-directional smart meter chances are good that it has an infrared LED which permanently sends metering data via a protocoll called SML. Sometimes you must enable this feature via a PIN which you can get from your grid provider. If you have such a meter you can apply a small device which picks up the infrared signals, the SML reader. This devices costs around 40€; it has WIFI and comes with a software (TASMOTA) which allows it to send the metering data via MQTT to a server or to respond to HTTP requests in JSON format.
See this video to learn how the metering data can be uploaded to a cloud account at ThingSpeak.
To control the inverter based on this data you need to have another piece of hardware and software: A Raspberry PI running Homeassistant, MWTT and NODE-RED. You would have to set up some Scripts in Node Red which ask the SML reader for the current energy needs and the talk to the inverter to adjust the maximum amount of energy it may produce at the moment. This process repeats every 5 or 10 seconds automatically. In the end the inverter of your PV system will restrict its power production to a value which guarantees that a definable threshold a backflow is not exceeded.
The sequence of steps is as follows:
- current flowing between your house and the grid
- official grid meter with infrared LED
- infrared signals in SML protocol
- SML reader with WIFI and TASMOTA
- WIFI messages with MQTT data or repsonses to HTTP requests from HA
- MQTT database on a HA (HOMEASSISTANT) server
- NODERED on the same server
- the HA must have an integration for the Growatt inverter
- NODERED script which picks up the SML messages on MQTT publishing or which request SML data via HTTP request and then tells the inverter
how much energy it is allowed to produce - The whole chain of commands runs every 10 seconds or so. The NODERED script will change the inverter setting only if there is a significant change in grid import/export data
Compared to installing a physical smart meter in your grid box this approach does not need an electrician and it is totally safe. But it costs more and need significant software skills. The Raspberry PI4 with 4GB will cost ~100€, so that you have to spend ~ 140€ in total plus some hours of installation work to get this solution going.
If you have good software skills or know someone who has these skills and will help you this may be a good way to proceed. Without a good affinity to home control software we would not recommend this kind of solution,
Advantages and Disadvantages of ES-Mini-2000
Advantages:
simple DC cabling (serial connection), voltages not too high (150..200V)
2000W AC output for many hours, because six or eight panels will deliver 2000W DC even under moderate sunlight conditions
Simple AC installation (connect to 220V single phase)
Flexible location: device is IP65 protected, can be placed outside or inside the building.
For only 60..80€ you can control the maximum amount of energy which the system feeds back into the grid.
For additional 400€ you get a USV battery with 1 kWh usable energy. This can supply energy to critical devices for several hours.
Disadvantages
The panels must have free access to the sky (no shading or you will get significantly less energy)
Installing the SDM630 would need work inside the grid connection box (as is always the case if you need to control the amount of energy backflow)
You must care for charging the USV system via selecting the charge rate and time schedule manually
You must connect the critical load devices (laptop, router, radio, tv, chargers for mobile devices, fridge, etc.) to the power outlet of the USV.
2) ES-Mini-800B (with Backup )
ES-Mini-800 comes with an integrated 2kWh battery and has a power socket for offline use.
Panels
The solution consists of four solar panels which can produce up to 1800Wp.
Inverter and Battery
Smart Meter
A smart meter (SDM630) should be installed in your grid box so that the inverter knows your energy consumption and can use excess energy for battery charge and adapt discharge to your current needs.
Without a smart meter you will have to create a schedule which defines when the inverter and/or battery deliver how much energy to your local grid (the remainder goes into the battery until it is full). For instance you may define a delivery of 150W during night and 800W during day. But this is only a rough guess and it will lead to situations where you buy energy from your provider although it would not be necessary.
Advantages and Disadvantages of ES-Mini-800B
Advantages:
Low DC voltages (< 60V)
Partial / temporary shading is not harmful (the system has 4 MPPTs)
1800W DC will be able to deliver 800W AC even under moderate sunlight conditions
Simple AC installation (connect to 220V single phase)
Relatively large battery capacity of 2 kWh (can even be extended)
The battery works automatically (if a smart meter is installed)
Grid feeding can be configured (with smart meter installed)
Disadvantages
long DC cables: Each panel must be individually connected to the inverter.
The inverter/battery (~ 30kg weight) must be placed inside the house near a place where you can connect the backup power socket to your critical devices.
There is only a maximum of 800W AC available.
Installing a smart meter is highly recommended but needs work inside the grid connection box
You must connect the critical devices (laptop, router, radio, tv, chargers for mobile devices, fridge, etc.) to the power outlet of the inverter/battery.