There are several main types of photovoltaic systems with different functionality. Their size depends on the specific needs and requirements of each site and customer.

3K Solar is an engineering company established in 2005 and is one of the first companies specialized in the professional design, construction of photovoltaic systems and installations for electricity production. 3K AD has extensive experience in the design, sizing and installation of solar systems for sale of the electricity, solar installations for own consumption, autonomous photovoltaic systems and solar hot water systems.

What are the different systems depending on their type?

  • Off-grid
  • On grid
  • Hybrid
  • System for hot water

Off-grid system

These systems are designed to meet entirely the need of energy consumption in a house, villa, business, office building or remote site without access to the electricity grid, such as mountain huts. They are calculated and designed according to the consumers and the load schedule of each site. These photovoltaic systems have a battery pack that stores the current produced so that it can be used during the night.


The On-grid solar systems are designed to generate electricity, and there are two options for managing the produced energy.

The first option is to consume the electricity produced by the solar panels, and in times of excess production you can send it to the grid. In the second option, the entire produced amount is given to the electricity transmission network and is purchased by the Local electricity distribution company or another electricity trader.

Hybrid system

Hybrid systems with a photovoltaic generator are solar installations with the possibility of adding a second source of electricity, such as a wind generator, diesel unit and others. These systems have countless possibilities. They can be integrated into smart grids or used as a UPS power supply.

System for hot water

The photovoltaic system for water heating is an innovative Bulgarian technology, developed entirely by 3K AD, as an alternative to solar collectors. In contrast, Thermosol K2 does not require the purchase of a new special water heater, but works with a standard boiler with a heater. The system works with 4 or 5 photovoltaic modules and 1 solar controller Thermosol K2.

What applications the different systems can have?

  • Photovoltaic systems for house or villa
  • Apartment
  • Business and industry

Photovoltaic systems for house or villa

Installing solar panels on a house or villa is a sure return of an investment.

Home PV systems are an extremely good solution for reducing electricity bills. The electricity produced by the solar system could be used both for self consumption and grid feed-in. Solar systems with power between 3 and 5 kW are ideal for households. These solar systems can be both on-grid and off-grid or hybrid depending on the needs, consumption and availability of grid power.


Placing photovoltaics in a residential building with apartments is possible. Although people are usually accustomed to seeing solar panels on the roofs of houses and villas, apartment owners can also take advantage of sunlight and generate some of their own electricity.

Whether on the roof of the building, on the facade of the building itself or on a suitable terrace for installation, apartment owners can also reduce their electricity bills with the help of solar modules. Small installations for water heating are ideal for owners of such housing.

Business / Industry

Any industrial plant, production site, workshop, restaurant, hotel or office building could reduce and even reset their electricity bills by implementing PV energy system.

Electricity bills are a major expense of any production process.

Integrating a photovoltaic system into a business is a long-term investment with many opportunities. Photovoltaics can be installed on a roof, facade, structures on the ground, etc.

The produced energy can be used both for own consumption and for direct sale to the Local Electricity distribution company.

What functions can solar systems perform?

  • Production, sale, own consumption
  • Lighting
  • Hot water
  • Watering

Production, sale, own consumption

Electricity produced by solar panels can have many applications. It may be fully consumed or only for sale. Electricity produced by photovoltaics can also be stored in a battery pack or so-called Storage systems, as well as part of it can be consumed right away, and additional production can be stored in batteries or transmitted to the grid.


Photovoltaic modules are widely used in street, park and garden lighting. They are suitable for powering advertising lighting on billboards and other equipment. The integration of solar photovoltaic lights into infrastructure lighting is becoming increasingly popular, and the installation of solar lamps as lighting in private properties is a long-term investment that pays off over time.

Hot water

The water heater is one of the main consumers of electricity in a household. Thanks to the controller for heating a PV boiler – Thermosol, developed by 3K AD, you could reduce your electricity costs for hot water by up to 70%. A photovoltaic system with a Thermosol controller can be installed both on the house and on the facade of a residential building and even a facade or terrace with appropriate exposure.


Agricultural lands are often located in places where there is no power supply and producers see themselves at a dead end looking for alternatives for pumping water from various sources – wells, boreholes or reservoirs. Photovoltaics successfully deal with this problem. There are specially designed water pumps for working with electricity from solar panels, as well as solar pump inverters, which use photovoltaics to drive pumps with a standard 230V power supply.

Some common capacities for solar systems

The size of a photovoltaic system depends on many different factors. Each solar installation is individually designed and tailored in the first place to the requirements and needs of the client. The capacities of the different systems can be calculated according to the consumption, the desired financial investment, the type of the system and the installation area.

  • 1 kW – Such a system would be suitable for powering 12V lighting, as well as other small consumers, such as TVs, chargers or for heating domestic hot water.
  • 3 kW – A photovoltaic system with a power of 3 kWp is enough to power a small cottage, mountain hut or to reduce the electricity bills of a household.
  • 5 kW – Solar generator with a power of 5 kWp could meet almost 100% of the needs of a household or office with 5-10 employees.
  • 10 kW – Solar power system with a capacity of 10 kW is suitable for relieving the costs of various production processes, and utilization of roof areas of halls, warehouses or livestock facilities on farms.
  • 30 kW – Photovoltaic generators with power over 30 kW are a profitable investment, suitable for any business or industry, which has areas suitable for installation like sheds and roofs. The electricity produced by such systems can be used in many different ways. Sales, reduced electricity costs and even additional profits are just a few of the opportunities that a photovoltaic system provides.

Various applications of photovoltaics

  • Roof or penthouse
  • Yacht
  • Camping
  • Caravan or camper

Roof or penthouse

Placing photovoltaic panels for electricity on a roof or canopy is a very good solution for utilizing this really unusable space.


The integration of solar modules is possible on almost any vessel. Photovoltaic panels for yachts can guarantee access to electricity even on longer trips.


When camping, you don’t have to give up on your phone, laptop or lighting. With the help of small portable kits you can generate your own electricity.

Caravan or camper

Placing solar panels on the roof of a camper or caravan allows longer journeys, even in places without the necessary infrastructure to charge batteries.

Why choose 3K AD as your partner in the construction of a solar system?

3K AD focuses its activities on the design, sizing, construction of photovoltaic systems for electricity. Development of innovative technologies in the field of the solar industry and infrastructure solutions for charging electric cars are also part of the company’s activities.

With over 15 years of experience in the industry and over 3000 completed projects, 3K AD relies on the experience of innovation and last but not least on a partnership with established names in the production of technological solutions for the solar industry.

As official distributors of leading manufacturers, we supply and install only the highest class equipment, as well as full warranty service.

We work with solar equipment and photovoltaic panels for electricity by established manufacturers such as: IBC Solar, Fronius, Steca, SMA, Victron Energy, Studer, Huawei, Phocos, Sungrow, GCL, Trina Solar, EcoDelta, Yingli Green Energy, Gioco Solutions and others.

* We prepare project documentation for connecting On-grid photovoltaic systems to CEZ, EVN, ENERGO PRO.
* Consultations, individual offers, installation and maintenance are an integral part of the company’s activities.

High quality

Quality is key to any photovoltaic electricity system. We sell and install only products of the highest class and leading names in the industry.


All products we offer meet World and European quality standards. Our work is performed in accordance with all requirements of applicable laws and regulations.

Individual solutions

All offers and projects are developed individually. They are tailored to the specific needs, special requirements and financial frameworks of the respective client.