ESS design and installation manual

Yes. ESS will reduce grid usage to a minimum, preferably to 0W, with or without feed-in enabled. It keeps the MPPT Solar Chargers working hard - even when the batteries are full.

A bit more detail with reference to selected modes:

The current options to work around this “Keep Batteries charged” issue are:

In optimize mode, ESS will only charge the battery with power coming from PV …except in two circumstances, both of which are related to battery health, and preventing life-shortening damage:

This question is typically asked by users or installers that are familiar with our previous configurations, for example Hub-1 or Hub-2, in a series installation rather than a grid-parallel installation. In that configuration the system used to switch to inverter mode when the batteries were full-enough.

That was OK, but it also had several disadvantages. An inverter offers a much weaker voltage supply than the public grid does …and that may lead to:

With ESS in Optimize mode the system will always remain connected - even when the batteries are full. And although connected, the power draw is not substantial - this configuration offers the stability of the grid without additional grid consumption.

In ESS, the conditions for the VE.Bus system to be in pass-through (ve.bus state: passthru) are:

Background: In an off-grid or backup system it makes sense to get a warning when the battery is almost empty. But in a system where the battery is only used to optimize self-consumption, and it's normal to fully deplete the battery every day, it isn't necessary to receive a notification.

- Disabling the Multi's low-battery warning pop-up on the CCGX is achieved by entering the Multi or Quattro Menu; selecting Setup and then Alarms. Set the Low DC voltage alarm to Alarm only.

The red blinking LED on the inverter/charger - which warns of a low battery - cannot be disabled.

- Suppress email notifications by logging into the VRM Portal, and setting the Automatic alarm monitoring to Only alarms.

This is normal. The current shown is the RMS current. Which does not represent real power, nor real energy being fed into the grid.

Especially around 0 W real power, you’ll see that the RMS current is very high. This is caused by the X-capacitors in the Multi.

Look at the Input power readings instead. They fluctuate a lot less, and are a more reliable indication of power and energy.

Note that these charge-cycle restart-mechanisms differ from the stand-alone MPPT Solar Charger algorithm: they restart the charge cycle every day. See the solar charger manuals for more information about this.(This link takes you to the Manual Download Page).

Switching off in overload, while connected to the grid, is caused by the active Loss of Mains (LOM) detection, linked to the country code as configured in VEConfigure3.

This behaviour occurs when the AC supplied on the AC-in of the Multi or Quattro is 'weak'. By 'weak' we mean that the AC connection to the utility has a higher impedance than usual. For example a generator, or an old or remote house connected with a too-long and/or too/thin cable to the utility.

For the solution and configuration options, see VEConfigure: grid codes & loss of mains detection.

Check list in case loads are being powered from the mains/grid, while expected to be powered from the battery:

First of all, check that the system is not preventing discharge because the battery state of charge is below a limit. See the Chapter 6 - Controlling depth of discharge.

Secondly, in case of a Managed Lithium battery, ie a battery with a CAN-bus connection, check that the battery hasn't disabled discharging: see the battery entry in the Device List menu, and then go to the Parameters submenu and see the Discharge Current Limit (DCL) entry. In case that shows zero, the battery is telling the system to not discharge any further.

Thirdly, feed-in may be disabled because the ESS Relay test is still pending: the inverter/charger (ie Multi/Quattro) in an ESS System needs to perform a relay test before it can use battery power. During the test, it needs to run in inverter mode shortly (~1 minute), and needs enough spare battery capacity to do so. In case the battery voltage is too low while connecting to the grid, the system switches on in pass-through and/or battery charging mode, and, while waiting for the battery to be recharged sufficiently (to do the relay test), it will not feed-in. Meaning that it will not convert DC to AC power, and hence will not power the loads from the battery, and similarly will also not convert any power coming from Solar Chargers to AC: will not power loads with DC-coupled solar power either. And the same: it will not sell excess DC-coupled solar power back to the grid.

The relay test will be performed once either the battery voltage has been recharged above 14/28/56 volt, or when the battery has been recharged to above 20% SOC. To check if a system is in this state, see the ESS Relay test entry in the Advanced submenu of the Multi/Quattro entry in the device list. It will show either Pending, or Completed. Note that that menu entry is only visible for systems with an ESS Assistant installed.

Fourthly, feed-in may be disabled when a grid code (like the German or Australian grid code) uses the aux1 input to disable feed-in, and aux1-in is used by something else (like an AC-sensor or a BMS), this way feed-in can be disabled. Simply un-check the option in the grid-code settings to prevent this.

Lastly, check that the rocker switch on the unit is set to On, rather than to Charger-Only. When set to charger-only, the unit refuses to discharge the battery. Note that to check this, you really need to physically check the rocker switch: you can't see its state by looking on VRM or on the GX Device. On a MultiPlus-II, this rocker switch is at the bottom of the unit and needs to be in the I position, not on II.

Finally, if all above didn't help - temporarily disable LOM to make sure that is not causing an issue. Detailes in this document: VEConfigure: grid codes & loss of mains detection.

See Q9

The recharge you are seeing might be part of the Sustain protection. Consider increasing the minimum SOC level. For example increase it with 5%; and then check what happens.

Or decrease the sustain voltages with VEConfigure, but take proper caution, especially for lead batteries as the sustain levels are designed to prevent early damage to the batteries.

Search this manual for Sustain to learn more.

The system will automatically recharge the battery (from the grid) when the SOC drops 5% or more below the value of ‘Minimum SOC’ in the ESS menu. Recharge stops when it the battery is recharged up to the Minimum SOC level.

No, you cannot. After unplugging the shore cord it can take up a moment for the system to detect the loss of mains and open the back-feed relay. During those seconds, the shore power plug will be live: there is 110/230 Volts AC on the terminals. The exact number of seconds differs per country and depends on the local requirements.

The same applies to other solutions where the wiring is not protected against accidental removing, for example a simple cable with end-user removable plug, such as a portable power supply.

This FAQ does not apply to systems that use an EM24 meter.

In an installation that has no dedicated energy meter, or one that uses an ET340 meter, energy imports and exports are accumulated per phase, and the total imported and exported energy is calculated as the sum of the imports and exports of all phases.

The utility meters in many countries use a different method of accounting: They will bill you on the Total net energy imported across all phases.

Due to differences between the two metering standards, there may be variation between the data shown on VRM, and on your meter.

In an ESS system where regulation is set to “Total of all phases”, the default setting, this variation will be more pronounced. This configuration specifically aims to make full use of the billing arrangement where you are not billed for the energy exchange between phases. It does however show up as simultaneous imports and exports in systems where total import and export energy is counted instead of total net energy, leading to differences between your utility meter and VRM.

This will cause the “to grid” and “from grid” counters on VRM to increase while the Multiphase regulation is in operation.

This phenomenon can also occur where PV-inverters are used, even if regulation is set to "Individual phase".

Customers using an EM24 meter, which instead accumulates the total net energy, are not affected by this, and should see accurate VRM metering in an ESS system where regulation is done over the total of the phases.