Essential principles

1. Autraky

Autarky principles

More than selfconsumption, we offer energy autarky. This autonomy will allow to fully manage your solar energy to provide a reliable supply for the next 20 to 30 years. The energy transition is on its way. Producing one's own renewable energy must become a priority for all those who want to consume energy.  At the level of individual housing, solar photovoltaic is a privileged source.

Solar energy means conversion electronics and inverters. With an equipment of the Studer next range you choose a high-tech converter which will play a central role in the energy production of your solar electric installation. The next3 has been designed to work as a solar battery charger and a hybrid inverter operating in both "ongrid" and "offgrid" modes. Its advanced and fully configurable features will ensure that your energy system works perfectly in all situations.   

When the next3 is connected to batteries and photovoltaic panels, it automatically recharges the batteries in an optimal way with all available solar energy. Depending on the selected programming, the solar energy can be fed into the grid or used for self-consumption only. The precision of the MPPT (Maximum Power Point Tracking) algorithm, the high efficiency and the low internal consumption ensure an optimal use of the energy produced by the PV modules.

Selfconsumption with storage

Professionals and amateurs are used to qualify the performance of a solar photovoltaic installation with its normalized production per installed kWp (kilowatt-peak) and the selfconsumption rate.  The selfconsumption rate is the ratio of what is produced by the solar system and what is consumed directly. This indicator gives an idea of where the solar energy goes: into consumption or back into the power grid. The selfconsumed energy is obtained by subtracting the amount sold to the grid from the total PV production. In fact, the difference is what remains in the house.

The selfconsumption systems are sometimes offering the possibility to add storage as an option, in order to maximise the selfconsumption rate. You can store in the battery some of the excess power before sending it to the grid, and you could then use this stored energy later during the evening.

From self-consumption to autarky

Existing for a long time but less used, the autarky rate indicates to what extent a house is powered by solar energy. The autarky rate really indicates if a prosumer uses his own energy or not, if he really covers his needs or not. 

It is not the overall production balance that is important for the selfsufficiency rate, but the actual direct use in the site. If a lot of energy is sold to the grid and bought back later, the house is not independent from the grid. Where your solar energy goes to and come from? Switch the point of view from the production to the consumption for the energy transition.

A step towards full autarky

With PV installed on your home, if there is enough production, you can cover your own consumption during the day. If loads are not covered, energy will be injected from the grid. If you produce excessive power, it will be sold to the grid to optimize costs. With autarky, you add storage to use during the night the energy produced during the day. You don't just optimize your costs, you produce your own energy and can be independent from the grid. Different autarky rates are possible, from partial autarky to full autarky. 

 

To achieve our energy transition goals, our energy must be produced locally and renewable to the maximum. More than using solar energy directly, the majority of our consumption must come from solar energy and for that we must not minimize the installed surface. This is justified by the decrease in the price of solar installations and the additional cost of the additional surface which is less. To have a good autarky (or autonomy) requires in general to use all the roof surface available for solar and to store the temporary surplus.    

 

The solar resource varies with the seasons, but also the consumption (heating, light needs with the length of the days, ...). The critical period for energy will be winter and it is better to have surpluses in summer to better cover its needs the rest of the year.    

 

To do this, it is important not to minimize the amount of solar and use the maximum on the surfaces available. This is especially true with the arrival of electric cars and their home charging.   That's why the next3 has two 8kW PV inputs for a total of 16kW. This may seem like a lot compared to the amounts installed in the past on a single-family home, but with the decreasing costs and the need for renewable energy, it is a wise choice.    

 

With a battery, excess solar recharges it during the day and the energy is discharged at night to cover consumption. This optimizes selfconsumption since the surplus does not go back into the grid but it also improves selfsufficiency since indirectly one uses one's own energy during the night.  To invest in autonom system means to become not only a consumer but also an actor of the energy strategy of the future. It stabilises the grid and contributes to a cleaner planet.

2. Internal architecture

The next3 concept, the power flow dispatcher is the brain of the system

In order to better understand how the energy management is done, the following diagram will help to identify the main blocks inside a next3 and how the power flow dispatcher plays a central role.

3. Energy strategies

Choose among a range of different strategies to configure your device for your offgrid and ongrid applications

Which are the typical applications that we could develop with the next3?  The next3 has been conceived considering our more than 30 years of experience in offgrid applications. The next3 is the perfect device for reliable and flexible offgrid applications ensuring a complete autonomy.  In addition, with the new AC source incorporating the security features, the anti-islanding and double relay and the control software to comply to all the new LV regulations, the next3 offers the possibility to go beyond selfconsumption. Let us lead you to the solar autarky.

Understand the general energy strategy

The next3 is a renewable energy friendly converter and always try to optimize the solar in the system. The energy management between all the converters and components of the energy system is done by the Power Flow Dispatcher  algorithm. This is at the core of the next system. 

Studer simplified the use of its product to be transparent to most of the end -user. Four standard energy strategies are available and can be selected during the configuration process in the wizard with only two questions to answer:

• is grid feeding allowed? This question is asked only if you have selected “grid” as connection to AC-source. If you selected “genset”, the grid feeding is forbidden.

• Is battery used for solar self-consumption optimization? That means the battery is used daily as energy buffer. Solar energy recharges the battery and is used during the night.

The 4 cases description, defined by those two questions are:

1. Use of battery for solarself-consumption optimization until a state of charge (SOC) for Back-Up. During the night, the battery is discharged until the given SOC. Under the defined SOC level, a reserve is left in case of blackout. The default level is 20% to use 80% of the battery as buffer for lithium batteries and 50% for lead acid batteries. During the day, when the solar power is produced, that energy is used to supply the AC loads, charge the battery[1] and inject the excess energy to the grid.
2. Full grid feeding: In this situation, the battery is kept full to be ready in case of blackout. The SOC for back-up is 100%. All the solar power produced supply the loads and the excess is injected to the grid.
3. Solar prioritywith zero export. The solar power is used to charge the battery and to supply the loads but is never sent back to the AC-source. In that mode the grid-feeding is not allowed. The battery is used as buffer. When there is more solar than loads, the excess will charge the battery. When the loads are higher than the production, the energy is taken first from the battery. Only when it is at the lower threshold (SOC for Backup) the grid will be used. Like that, there is still some energy left in the battery to run some loads when a blackout happens. When the battery is full and the load is small, the MPPTs will reduce the production, causing some solar energy to be lost.
4. Offgrid or Weak grid: AC-source is a genset or a grid where the injection is forbidden. The battery is charged to the maximum as soon as the AC source is present ensuring to have energy available in the next blackout event. 

[1] Battery is loaded up to the SOC for grid feeding level. SOC for grid feeding is 100% by default but it can be modified in advanced mode.

4. Unique technical features

Ready for autraky!

Our proposal: an offgrid inverter ready for the grid.

What’s a next3?  It's a new hybrid inverter charger all-in-one  

- 15kW looks a lot, but remember it is nominal power   

- Battery inverter from 48V to 3phase AC, compatible with a range of different batteries technologies including lead-acid and lithium  

- 2 Built-in MPPT solar inputs   

- Integrated transfer module with a 3 phase AC source, with security anti-islanding for grid applications according to the latest LV regulations  

- A unique AC flex interface configurable as 2 nd  source or 2 nd  load for smart energy strategies  

- A completely new comprehensive user interface for configuration, follow-up, monitoring and communication 

- A wide range of integrated features: CAN BMS and RS485, battery temperature, fully configurable remote entries and auxiliary contacts, and many more.

The power flow dispatcher, the innovative and patented brain of the system

An An optimisation control algorithm with ultra fast reactions

High voltage DC link for robustness and autonomy

High conversion efficiencies from solar to loads and from solar to grid

AC flex, a unique and versatile AC interface 

Configure the AC flex as a second AC input or second AC output.

As a second input can be used to centralise the management of grid and backup generator or even two different generators in an offgrid application. As a second output you can have a completely automatic and fully monitored load, for electric mobility, secured loads, and other applications. 

6 arguments for professional installers

The next3 is the best tool for professional integrators and installers.

Fully grid interactive with special functions