RESSG is that kind of equipments for utilization of power produced by PV panels and other renewable energy equipments (like wind turbine, micro hydropower plant) what

                                                                                                                 - has household sized (3.6 kW) power

                                                                                                                        - does not feed into the grid

                                              - reduces the amount of energy purchased from the grid to the extent of the renewable energy used

                                                                                    - produces DHW (domestic hot water) in a power-controlled manner

                                                                                                            -  can automatically revert to direct grid supply

 - in the event of a permanent shortage of renewable energy, the system switches itself off and switches to direct grid supply, then the system is automati-   cally switched on when renewable energy reappears

- consumers can be divided into two renewable energy supply groups

- can be expanded with batteries, in which case it can also be used as a UPS, even in the absence of renewable energy

- can be expanded with an aggregator, in which case there will be supply even in the event of a permanent renewable energy shortage

Applications

It can be used in all places where, in time of availability of the the renewable energy  the need for power is constantly present and its continuous use is ensured (in the case of PV panels, during the day).

In the case of the  PV renewable energy source, they are:

Those households where they are at home during the day, so their demand for electricity is continuous during this period, especially:

                         - homes of families with small children

                         - multi-generational family homes

                         - homes that are also workplaces (home office)

In the hospitality and turizm:

                         - restaurants, bars

                         - guesthouses, apartments

                         - accommodations

                         - especially ideal for summer seasonal catering units 

Health and social accomodations, where the need for power and domestic hot water is constantly present:

                         - small hospitals

                         - clinics

                         - several care homes

                         - homes for the elderly

In the small businesses:

                         - small manufactures operating in continuous shifts even on weekends

                         - convenience stores

                         - petrol stations

In the agriculture:

                         - livestock farms

The operation of the system succintly

The supply of connected consumers to the RESSG is primarily covered by renewable energy

If there is not enough renewable energy available, then the missing energy is proportionally supplemented from the grid so that the less renewable energy available in the meantime is also utilized

It is able to supply one group of consumers divided into two renewable energy supply groups with renewable energy, while the other group is supplied from the grid in the absence of more renewable energy

If renewable energy is available in excess of the demand, the surplus is primarily used for DHW production, and then, if it is saturated, it is fed secondarily into the battery (the battery is not a necessary element of the system)

All generally used single-phase household consumers can be connected to it

It remains operational even in the event of a power interruption (up to the extent of available renewable energy and, if there is a battery, its capacity), thus it is possible to eliminate consumer supply caused by unexpected weather, which may last for several hours, at least for the most important consumers (heating circulation pump, refrigerator, freezer)

In the event of a permanently low level of renewable energy (e.g. a permanent cloudy weather for PV panels), it switches to the grid supply

In the case of PV panels, the complete system automatically turns itself off at night

In the case of PV panels, it automatically puts the complete system into permanent operation during the day

Filters out grid disturbances (except when connected to direct grid supply)

PV panel installation options

There are no technical restrictions on the number of RESSG PV panels, their orientation and inclination, the user can freely choose the number of PV panels to be used and their installation direction in the most economical arrangement for their use, up to the limit of the chosen performance.

Split roofs provide a natural solution for their placement. Partial shading, the so-called in case of "chimney effect", only the production of the shielded PV cells is reduced, the production of the other PV cells continues undisturbed, so that it does not require separate PV cell control optimizers.

RESSG ensures that the user can place each PV panel at a different point, turning and tilting it in different directions, adapting the production of the PV panels to their own usage needs. If the user's needs require a lower morning output and a higher afternoon output, it will be economical to turn fewer PV panels in the SE direction and more in the SW direction. The angle of inclination will affect the optimization according to the seasons.

The PV panels are connected in parallel, so there is no high voltage on the roof and the number of PV panels can be expanded at any time.

Operating specifics

RESSG utilizes renewable energy and energy purchased from the grid at the same time, but at the same time it does not feed energy into the public grid, it can supply connected consumers separately from it. As a result, its operation is ensured even when the grid is interrapted.
Energy traffic between the grid and RESSG is one-way, only consumption happens from the grid , so the user does NOT NEED:
- make a request to the power supplier
- have to prepare a connection plan
- modify  the existing  contract with the power supplier
- to account for the amount of power produced, so you don't have to pay a grid usage fee to this extent

In case of correct dimensioning, the production of renewable energy can be fully utilized.

During operation:

- the supply of connected consumers is primarily covered by renewable energy

- if it is not sufficient, then the missing power is made up from the grid

- thanks to the division of consumers into two groups, in case of little renewable energy, one group is supplied with renewable energy and the other from the grid

- if there is a surplus power, it will be used to produce DHW (domestic hot water) or heating hot water (buffer storage)

- all generally used consumers can be connected

- remains operational even in the event of a power interruption (up to the extent of available renewable energy)

- in the event of a permanently low level of renewable energy, it automatically switches to grid supply

- in the event of a permanent shourtage of renewable energy (overnight in case of PV panel), the entire system automatically switches itself off and switches to grid supply

- in the event of a permanent existance of renewable energy  (in the case of PV panels, during the day), the entire system automatically starts up

- filters out grid disturbances (except when switched to direct grid supply)

- suitable for efficient (slow) charging of the EV (electrical vehicle) from renewable energy

Optionally supplemented with a battery:

- commercially available batteries of any capacity can be connected to the RESSG

- excess renewable energy is stored in them, so self-consumption is fully feasible

- so it can perform UPS and limited emergency functions at the same time

During its extended operation with a battery:

In the event of a power interruption:

- ensures uninterrupted energy supply to consumers up to the capacity of the battery

- switching for the battery is automatically happening

- the switching happens without a transition time

 In the event of power returning:

- the return to normal operation happens automatically

- the switching happens without a transition time

The battery does not participate in the energy cycle, except in the event of a power interraption:

- so its service life remains long

- so its charge will always be at maximum

The battery is charged exclusively with renewable energy.

Completed with a generator set:

- able to perform long-term, unrestricted emergency operation (up to the fuel reserve of the generator set)

Operation of the RESSG

Scheme of the RESSG

Operating types list:

1. operation from the inverter and the grid together
2. operation directly and exclusively from the inverter
3. operation directly and exclusively from the grid
4. automatic and uninterrupted switching between the grid and inverter outputs
5. night mode, keeping the inverter off
6. power-controlled domestic hot water makeing

Detailed description of the operating types:

1. operation from the inverter and the grid together

The consumers are supplied at the relay switch (ETM, Energy Transfer Manager) setting to supply from the inverter when the grid is in operation. Due to the two-way feeding of the inverter, the output power is controlled by the incoming energy levels.

This operation can have the following options:

1.1 supply from the output of the inverter

In this case, the power of the renewable energy sources is sufficient to satisfy the demands appearing at the consumer output of the inverter, the momentary surplus is directed to the boiler, the momentary deficit is compensated by the AC/DC converter (adapter unit) from thegrid.

1.2 direct supply from the grid

In this case, the power of the renewable sources is not sufficient to satisfy the demands appearing at the consumer output of the inverter, in order to reduce unnecessary transmission losses, the system switches the relay transfer switch (ETM) to supply from the grid and supplies the consumers directly from the grid. It removes the consumer load from the inverter output, while leaving the domestic hot water heating operation intact. In this case, the inverter is only loaded by the power demand of domestic hot water heating, which is continuously controlled by the energy level of the system at the output of the inverter.

1.3 in addition to supplying one group of consumers from the inverter output, supplying the other consumer group directly from the grid (simultaneously as described in points 1.1 and 1.2)

2. operation directly and exclusively from the inverter

This can happen when there is a grid interruption. In this case, the supply of consumers is directed to the output of the inverter, of course only to the extent of the currently available renewable energy.

3. operation directly and exclusively from the grid

In this case, the consumers are connected directly to the grid by the relay transfer switch (ETM), the output of the inverter towards the consumers is empty, there is no energy flow. If the inverter is operating, i.e. there is a small incoming renewable energy, then it is only fed into the boiler.

4. automatic and uninterrupted switching between the grid and the inverter outputs

The transfer switch (ETM) is a fast transfer switch solved exclusively with relays, the grid and the inverter are always galvanically isolated from each other, no current can enter the grid from the output of the inverter. Consumers are supplied in an alternative way, double AC feeding is excluded.

The transition from mode 1.1 to mode 1.2 is activated when the power of the renewable energy sources provided to the system remains below the power demand at the output of the inverter for at least 2 minutes.

The transition from mode 1.2 to mode 1.1 is activated when the power of the renewable energy sources provided to the system exceeds the power demands at the output of the inverter for at least 2 minutes. Additional performance surpluses are used by the system to produce power-controlled domestic hot water.

5. night mode, keeping the inverter off

In the case of weather-dependent renewable energies (PV, wind), even because of their dependence on the weather, it is not possible to determine the amount of renewable energy available in advance. However, there is one exception to this, the period of PV energy availability that we can say with certainty that it will certainly not be available during the dark period of the night.

In the case of PV panels, it makes no sense to operate the inverter and control at night, because in the complete absence of renewable energy, the system will definitely remain in the grid supply operation, and the domestic hot water heating operation will also cease. The output of the available zero renewable energy falls below the domestic heat water energy supply threshold, and the output regulation controls it to zero. The night operation is activated when the renewable energy output for the system drops below a certain level for 10 minutes. Then the system control switches off the entire system. The rising sun wakes the system from sleep, it detects the increasing power of renewable energy, which causes the entire system automatically turn on and prepare to serve the daytime load. Thanks to this, the night consumption of the system is zero.

6. power-controlled domestic hot water makeing

This operation is an important element of the system. The basic principle is that it activates above a given energy level and produces domestic hot water  with a performance dependent on its level. It works connected to the output of the inverter in front of the relay transfer switch (ETM), which means that it is always in operation, it is active even when the consumers are supplied from the grid, and it enables the full utilization of the produced renewable energy.

This introduction of the RESSG is a short description only.
The introduction of the automatic and perfect operation of the system exceeds the scope of this short description.