This ist the cheapest solution we could find for a system with 2000W AC power with some degree of backup capabilty.
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 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 (125€). For configuration and monitoring you 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 have a solution which feeds all of the solar energy it can harvest into your local home 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 the DC wires may be long (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 a short DC cable and a longer AC cable.
You need mounting material for the panels depending on the roof 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 (with or witthout 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) will 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 in 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 configure and control the UPS to help you in saving energy cost.
A device like a Shelly Plus Plug S (20€) can help you. It can be programmed via a mobile app to connect the UPS to the AC line for certain time periods. And it can be switched on/off via the app, of course.
If you adjust the load rate of the UPS to 200W it will need 6 hours to charge (when fully discharged). If you expect to have solar energy between 8:00 and 18:00 you could program the shelly timer to connect to the grid at 10:00 and to disconnect at 16:00. In the succesive 18 hours the UPS could slowly discharge at an average rate of 60W. In such a scenario it would be your task to identify devices which in sum require ~ 1kWh in 16 hours. A combination of charging devices, router, laptop, fridge and some lamps may be possible.
It is technically possible to install a device on the output side of the UPS which detects a situation where the battery has gone empty. This could be a shelly UNI with a suitable sensor. The shelly UNI can send a http request to the shelly plug so that it reconnects the UPS to the grid instantly regardless of its timer. Maybe we will show a solution im ore detail for such a scenario in future.
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.
Advantages and Disadvantages of ES-Mini
Advantages:
Unbeatable price 455 + 60 + 400 + mounting material, TOTAL < 1000€
simple DC cabling (serial connection), voltages not too high (300V)
2000W AC output for many hours, because the 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€ you can control the maximum amount of energy which the system feeds back into the grid.
For additional 410€ 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 less energy)
Installing the SDM630 would need work inside the grid box (but this always the case if you need to control the feedback energy flow)
You must care for loading the USV system via selecting the load rate and time schedule manually
You must connect the critical devices (laptop, router, radio, tv, chargers for mobile devices, fridge, etc.) to the power outlet of the USV.