Optimization of self-consumption

1. Optimization of self-consumption

The Climkit optimization system makes it possible to increase the self-consumption rate of a photovoltaic installation by controlling certain devices according to the production of solar energy.

The surplus sent to the electricity network is thus limited and we also gain autonomy by producing, for example, hot water with solar energy.

The devices (water heaters, heat pumps, radiators, swimming pool pumps etc.) are controlled via a relay.

It is also possible to control certain charging stations for electric vehicles (via Wifi or Ethernet).

Detailed connection of a relay on the I/O module

The relay I/O module has 4 relays.

2. How the algorithm works

The system evaluates the electrical power delivered or withdrawn from the electrical network every minute.

In the event of a pent-up surplus, it activates the various configured and connected devices.

For example, if there is a surplus greater than or equal to 1000 W, it turns on the 1000 W water heater.

Conversely, if there is no longer any surplus and energy is withdrawn from the network, then the system switches off the devices necessary to limit the withdrawal.

The devices are switched on and off according to the selected operating modes, for example in "Solar only" or "Solar and timer" mode. See Configuration below.

It is not possible to set activation or deactivation priorities among the devices, the latter are only controlled according to their nominal power in order to maximize self-consumption.

In order to be as flexible as possible, it is recommended to connect devices with the least power possible so that they already switch on with little surplus.

For example, we can connect each phase of a 3000 W water heater to an independent relay to benefit from three 1000 W levels.

Special remarks

Minimum power and number of phases of a terminal

In general, an electric vehicle needs at least 6A for it to start charging. Some vehicles need 8A or 10A. A minimum set below may cause an error on the vehicle.

This minimum of 6A is the same in single-phase and three-phase. That is to say 1380 W in single phase 230V or 4140 W in three phase.

Consequence on optimization: a vehicle connected to a three-phase terminal needs a minimum of 4140 W of solar surplus for the system to start charging.

In the case of small photovoltaic installations (5-8 kWp), the surplus necessary to activate the terminal will only be available in summer and during the day.

It is therefore recommended in these cases to connect the 3 phases of the terminal to 3 relays or at least to 3 independent switches so that the user can easily switch from one to three phases. See diagram above.

When you want to change the number of phases of the terminal, you must cut off the main circuit breaker of the terminal, switch on or off the phases of the connection and re-engage the terminal.

The optimization system does not allow you to control the phases and automatically switch from single-phase charging to two- or three-phase charging.

Putting the vehicle on standby

When a vehicle is connected to the terminal but the solar surplus is not sufficient for charging to begin, the vehicle is put on hold until the terminal gives it electricity.

In some cases, the vehicle may go into full standby after a while and when the terminal gives it electricity again, charging does not start until the vehicle is "wake up" by the user.

This case is common when the vehicle is plugged in in the evening and the excess solar power will not be available until the next morning.

Some vehicles can be updated to avoid these unexpected sleeps. Consult the vehicle manufacturer.

Old vehicles

Some older vehicles (before 2012-2014) do not support power variations during charging and are therefore not controllable via the optimization system.

Heat pumps (SG-Ready)

Most modern heat pumps (PAC) are equipped with a potential-free contact which, when closed, gives an instruction to the internal management system of the PAC.

In general, it is possible to configure the heat pump so that it increases its heating setpoint or produces more hot water when this contact is closed.

By connecting a relay from the optimization system to this contact, we can force the heat pump to turn on when the photovoltaic installation produces excess energy.

Consult the heat pump manufacturer.

Connecting a three-phase water heater

Many water heater resistors are connected in 3 wires without neutral. It is therefore necessary to connect a neutral to control each phase individually.

Otherwise, it always takes at least two phases for it to activate.

We can then use two relays and control: phase 1 and 2 with the first relay and 1 and 3 with the second.