Demonstration Center 4


Edit Content

The demo center in Varna, Bulgaria was launched in January 2021 at a local municipal office building. The center showcases a number of CSSC solutions by using solar energy and biomass to cover the electricity and heating needs of the building.

Solar panels have been placed on the roof of the building and the electricity generated is being stored in batteries.  Part of the electricity produced is being used by a charging station for electric vehicles. The biomass heating unit installed in the building is employed for its heating while a solar hot water PV system ensures that hot water is available.

It is the only energy positive building at local level and has achieved complete energy self-sufficiency.  This means that it no longer relies on the local electricity grid, which tends to be unstable. All in all, the demo allows for an increase in the use of renewable energy, reduced CO2 emissions and a lowering of energy consumption.

The charging station is also available to the local community, provided users download the necessary application. By enabling greater access to the charging station, the demo site plays an active role in making Varna a greener city and transforming its mobility sector!

To summarize, the demo center aims to:

  • generate electricity and to save money on electricity bills
  • achieve energy independence
  • be well equipped to resist sharp rises in energy prices through renewable energy production
  • monitor electricity production and consumption in real time
  • show that such investments are secure
  • prove that buildings can ensure access to electricity even if they are not connected to the local grid!
  • demonstrate how carbon footprints can be reduced!
Edit Content

Components of demo center:

  • 19,3 kWp PV module systems – 55 PV panels
  • 3 Solar charge controller – Smart Solar MPPT 250/100
  • 1 Invertor – Victron Multiplus 48/5000/70
  • 30,72 kWh Battery BYD Premium LVL – 2 batteries
  • 22 kW Pellet boiler Ferroli
  • 32 kw CNG boiler – Victrix 35
  • 2 Electrical boiler for DHW
  • 2 DHW – PV controller ThermoSol;
  • 2,5 kWp – Solar hot water PV system
  • Monitoring equipment
Edit Content
Edit Content
Edit Content
Edit Content
Edit Content
Edit Content
Edit Content

Different e-charging infrastructure facilities for charging e-vehicles will be implemented on the site. The power range of the charging points is 3.7kW, 11kW, 22kW or 50kW (AC and DC technology), whereby the connection between the vehicle and the charging infrastructure is made using wired technology.

Edit Content
Edit Content
Edit Content
Edit Content

Energy consumption has steadily been increasing in recent years due to growing demand linked to improved living standards, the construction boom and a greater number of consumers. Since the energy supply network was not designed to cover this increased demand, disruptions in electricity supply have become more frequent. At the same time, a spike in energy prices has been observed.

Using photovoltaics and batteries makes it possible to unload the energy network and to simultaneously increase the quality and security of the electricity being supplied.  Moreover, it partly guarantees that the price of the energy being consumed remains constant since the demo center is in charge of its own production.

The main challenge of the demo center is how to combine the PV panels, invertors, batteries and boilers on the one hand and the energy consumers as well as the energy management system on the other. Moreover, it is important that the entire system remain financially viable. 

Thanks to the concept applied in the demo center, it can be entirely energy positive, which means that it can produce more energy on-site (from renewables) than it consumes while maintaining comfortable temperature levels around the clock throughout the year.

Since it is an energy positive building, it is presumed that the building’s energy consumption should suffice to cover heating, cooling, ventilation, dehumidification, domestic hot water and integrated lighting systems. In addition, to qualify as energy positive, the renewable energy should also be produced on-site. For larger energy positive buildings, services such as elevators should also be included in the consumption supplied by on-site renewables.

Edit Content

Feasibility study and detailed planning of demo-center


Technical specification of components


Procurement of components


Purchase and delivery of components


Installation of components


Initial operation of demo-center


Edit Content

A few key performance indicators were identified for the demo center, which will be covered in the “live data” section of the platform. The purpose of this live data is to enable beneficiaries to track the implementation of the demo center.  

Edit Content
  • Total investment 50 000 BGN
  • The funding sources are blended between the organization’s own sources and external funding.
  • 25,000 BGN budgeted under the CSSC Lab project.
  • Electricity production – 8 000 kWh/year
  • Heat production – 15 000 kWh/year
  • Saved cost – 6500 BGN
  • Total payback period of whole demo center – 7,7 YEARS

PV system 19,3 kWp


         15 440 

Battery 30,72 kWh


         10 000 

Electricity production 01.09.2021 – 01.09.2022


         25 090 

Electricity price (grid tariff)








      8 028,80 

Payback period (CSSC demo equipment)



Saved CO2 per year

t CO2


Edit Content
Click on the Edit Content button to edit/add the content.
Edit Content

Since Varna enjoys many hours of sunshine throughout the year, the demo center focuses on using solar energy for meeting its electricity needs and is heating with the help of biomass. To do this, solar panels were installed on the roof of the office building and the electricity generated is being stored in batteries. This is then being used to meet the electricity needs of the building as well as for the charging of electric vehicles close-by. The biomass heating unit serves the purpose of heating the building while the solar hot water PV system ensures that hot water is available. Combining all these solutions, the office building is entirely self-sufficient and does depend on the local electricity distribution system. At the same time, it is a zero-emissions building, helping make Varna a greener city. More concretely, the technical solution being used is based on a combination of a PV system, a battery system and an energy management system. Another important issue is that the system be economically justified. To reach the goal it is very important to define the electricity consumption during the year. One of the biggest consumers is the boiler for domestic hot water (DHW). The consumption is almost the same throughout the year.

The decision is to implement a special PV system for DHW. There is a special controller which converts DC into AC. With the help of this controller, it is not necessary to use very expensive invertors and other equipment. Although the electrical sine wave is not high quality, it is completely enough for working process of the boiler.

Another issue is the hourly rate of electricity consumption. The main consumption is from 8:00 to 10:00 AM and from 16:30-17:30 PM. The best position for PV producing is to be oriented on the south incline 45 degrees, but the maximum yield will be from 11:00 to

16:00. To cover the mismatch between generation and consumption more battery capacity is needed. But the battery equipment is very expensive, costing about 3000 EUR/kW. The PV equipment is cheaper than the battery – 400 EUR/kWp. The selected approach is to arrange the PV panels on the east and west side, which makes it possible to generate enough electricity exactly when needed.

The price of energy is increasing continuously, all type of fuels like CNG, wood pellets and other have very unstable prices during the year. The approach adopted is to have flexible boiler configuration and according to the price use either CNG or pellets.

The overall electrical and heat generation system works simultaneously and is managed by the energy management system (EMS).

The system is working properly and delivering the necessary energy. During the summer months there are surplus of electricity, which can be used for charging electrical vehicles.

Edit Content
Live Data

Date and time of last update: 2023-May-30 02:06

PV system production
EV Disconnected
PV - part 1 - production
PV - part 2 - production
PV - part 3 - production
Battery state of charge
62.0 %
Battery power
Battery status
EV charger power
Status of EV charger
0.0 A
historical data
PV System
PV System Consumption Solar
Last 2 Days Last 7 Days Last 30 Days Last 90 Days Last 6 Months

Consumption Production
State of Charge Na-Ion battery State of Charge Li-Ion battery
Cold Heat
To Grid
0 kWh
From Grid
0 kWh
PV - total production
0 kWh
Total power consumption
1 kWh
0 kWh
To Battery
0.00 kWh
Direct Use
0.00 kWh
From Battery
1.29 kWh
From Solar
0.00 kWh
Total power consumption
1 kWh
Edit Content
EU sees the future in the development of renewable energy. This will not happen without a stronger role for energy storage and flexibility

EU sees the future in the development of renewable energy. This will not happen without a stronger role for energy storage and flexibility

The European Commission today presented a key proposal for changes to the energy market, responding

Czechs have taken up the fight against high prices: solar panels covered tens of thousands of roofs last year, the market grew by 366 percent.

Czechs have taken up the fight against high prices: solar panels covered tens of thousands of roofs last year, the market grew by 366 percent.

The sharp increase in energy bills, the uncertainty resulting from the ongoing Russian aggression in

ConPlusUltra supports the sustainability initiative of Raiffeisen Landesbank Burgenland

ConPlusUltra supports the sustainability initiative of Raiffeisen Landesbank Burgenland

The CSSC project addresses the energy security and energy efficiency demand of medium-sized and smaller

Scroll to Top