Victron HUB 4
What is the direct effect of this?
The direct effect of installing a Victron HUB 4 home energy storage and self-consumption system will be in the form of savings on your electricity bill. During the day, the sun is intermittently hidden by clouds passing by. Which reduces the generation of electricity from PV Panels.
So if we imagine we are drawing 1000 Watts of power in our home during the day (1kWh every hour). With our base appliances powered on, such as fridge, freezer etc. If we have 4kWp of PV Installed on our roof during a sunny spell we are generating 4kWh of electricity every hour. So generation minus consumption leaves 3 kWh of energy which is sent back to the grid. And we only get about 4.85p for each kWh (But remember exported power is assumed and not measured). Now it starts to rain and there is heavy cloud rolling in. Now our PV Modules are producing no energy (well very little). So we now have to buy the power for our base appliances (1kWh Every Hour) from the grid, which we are charged about 12 – 14p for each kWh.
With a Victron HUB 4 home energy storage and self-consumption system installed, when the rain and clouds set in we would draw that 1kWh of energy required from the battery which has stored the free energy we created on our PV Modules previously. And we would save the 12 – 14p we would have been charged by the grid power company.
The Victron HUB 4 Installation is connected parallel to the grid via the AC Input, this allows the system to be much smaller than the load of the home and also allows the system to be connected with PV Installations which are larger than the inverter charger. The 1:1 rules does not apply with this installation.
It is advised to use a Lithium Ion battery with these systems, this is because Lithium Batteries can be charged with a high current over a short period of time. This means that a couple of hours of good sunshine could be enough to fully charge the battery bank. This will increase the rate of self-consumption in a day. Lead Acid batteries can also be used but they do not have the same charge efficiency as Lithium Batteries. Lithium batteries are of course much more expensive than Lead Acid batteries although they do last much longer and are more capable of handling the high levels of cycling which are present in a Victron HUB 4 Installation.
In the event of a power cut the Victron HUB 4 will still operate and you can power any critical loads, although the PV Modules and Grid Inverter will stop producing electricity. You can power your critical loads until the battery has depleted. This happens because the Grid Inverter will not receive any AC Power during a power cut.
Sustain Mode, In the event of no solar energy the Victron HUB 4 will discharge the battery to the sustain level, this ensures the battery level will remain and be sustained at a level which will not decrease the batteries life expectancy or damage the battery in any way.
Dynamic Cut Off, Instead of a fixed DC input low shutdown voltage, the (new) dynamic cut-off looks at both discharge current and battery voltage. When a high current is being drawn from the battery, a low DC cut-off voltage threshold is being used, for example 10 V. And similarly, when the battery is only being discharged slowly, a high DC cut-off voltage is used, for example 11.5 V. This way, voltage drop caused by battery internal resistance is being compensated for, and battery voltage can reliably be used to stop discharging when the battery is discharged.
Generator Start / Stop function, the Victron HUB 4 System can also be configured to automatically start and stop a backup generator based on battery level or load level.
A Victron HUB 4 System will be best suited to a household which has a moderate amount of energy usage during the day (someone at home) as the battery can be cycled (charged and discharged) throughout the day. Giving a higher amount of self-consumption. A medium sized battery bank would be most efficient for this system.
More information can be found on the Victron HUB 4 system on the Victron Energy Website