An issue that has been discussed among the photovoltaic professionals is that of the battery voltage in the residential storage systems.
Is there a better configuration than others?
Basically there are three type of systems:
» those in low Voltage, about 48V;
» those said in “high Voltage”, 400V approximately;
» high voltage modular systems (from 250 to more than 500V). The latter are realized by composing several battery packs, like in Lego® bricks, until the wanted capacity is reached.
In addition to assessing the type of battery, we need to consider the complete system, including the electronic power that performs the coupling with the network or with the build system: you can think that the greater economy and efficiency is obtained by connecting the battery to the DC side of a standard photovoltaic inverter and using the DC/DC converter input stage.
With this configuration, the most suitable battery voltage would be starting from 1/3 – 1/4 of the inverter DC bus voltage and the system would see an economy as regards installation costs (cables of reduced sections and switches).
The advantageous battery
The producers of residential storage systems consider advantageous the use of that kind of cells that are spreading also for other use, especially in the car industry, that makes the price competitive in terms of €/kWh.
This leads to the use of cells with a capacity in the range from 40-60Ah and voltages of about 48V.
High voltage systems contain lower voltage batteries (around 100V) and a DC/DC converter that raises the voltage up to the rated voltage.
Compared to this type of configuration, high voltage modular systems do not need an additional converter and potentially have a higher efficiency.
Battery standard configuration and conversion system
It should be pointed out that today the standard configuration battery and conversion system has not yet been consolidated: 48V batteries have economic advantages, those in high voltage have potentially higher return.
ABB: REACT 2
“All-in-one” storage solution, inverter with integrated high-voltage (200V) lithium-ion battery for long life.
- Ideal for new installations and retrofits
- Power ratings 3.6 and 5.0 kW
- Storage capacity ranging from 4 to 12 kWh
- Flexible design with the possibility of integration at any time
Storage, Fronius, AC side storage system, DC side storage system
Fronius Energy Package DC and AC connectable systemsStorage, Fronius, AC side storage system, DC side storage system
Fronius Energy Package DC and AC connectable systems
This storage solution is composed by a Fronius Symo Hybrid and a Fronius Solar Battery.
In a Symo Hybrid inverter you can insert the Solar Battery accumulator at any time.
Easy to install, the inverter is wall mounted and the battery is standing.
- Powers of 3, 4, 5 kW
- Energy from 3.6 to 9.6 kWh
- It is also possible to connect the accumulation system to the AC side
Storage, Fronius, Inverters, Fronius
Fronius Symo Hybrid
Fronius has extended its range of three-phase inverter MPPT replacing an entrance with a battery charger so you can put a lithium iron phosphate with a capacity ranging from 3.6 to 9.6 kWh can also be used in case of blackuot.
Remain unchanged all the control functions and standard monitoring Snapinverter Fronius.
The result: the sun by day, the sun at night and the sun during the blackout.SKU: n/a
Storage, Huawei, DC side storage system, Inverters, Huawei
Huawei SUN2000L-2/3/3.68/4/4.6/5KTL smart energy center
Storage, ABB, All-in-one DC side storage system
The solution designed by ABB for storage is called React, synonymous with Renewable Energy Accumulator and Conversion Technology, it allows you to earn from 2 kW up to 6 kW, for maximum comfort and energy use.
1] Enhance self-consumption
2] Integrated inverter + battery
3] The battery pack is expandableSKU: n/a
SE 3500 to AC coupling
L’inverter SE 3500 ad accoppiamento AC è concepito per essere utilizzato su impianti esistenti con inverter non SolarEdge o con inverter trifase SolarEdge per aggiungere l’accumulo sul lato alternata dell’impianto.
- Studiato per implementare la soluzione StorEdge su impianti esistenti monofase o su impianti SolarEDge trifase
- Compatibile con StorEdge Interface per batterie Tesla PowerWall ed LG Chem RESU
- Sicuro ed affidabile
The StorEdge Interface is the intelligent core for implementing storage solutions with SolarEdge inverters.
Simple installation and connections for battery and measurement counter SolarEdge
- Compatible with all the SolarEdge Single Phase Inverter
- Compatible with Tesla powerwall and LG Chem RESU
- Designed to eliminate hazardous voltages during installation, maintenance and in case of fire
Storage, SMA, AC side storage system, SMA, Inverters SMA
SMA Sunny Boy Storage
Inverter designed for high-voltage batteries for domestic use. Sunny Boy Storage allows economic integration, simple and flexible storage solutions for photovoltaic systems both new and existing.
1] It is simple and flexible
2] Economic Integration
3] even for existing plantsSKU: n/a
SolarEdge, Inverters, SolarEdge, Inverters SolarEdge
The new SolarEdge single-phase inverters thanks to the patented HD-Wave technology are even safer and more reliable.
The new bridge conversion architecture reduces the number and size of the components, the result being the smallest and lightest inverter of its category with maximum efficiency of 99.2%.
The 12-year standard warranty remains unchanged, free local and remote monitoring at the integrated module level and arc detection function.SKU: n/a