Do you live in an apartment? What does it sound like to save approximately 450 euros per year through our domestic water heating system with solar energy collected by photovoltaic windows?
Because energy prices are high, we have developed and tested a system that supplies the electric heater directly with the energy produced by photovoltaic windows.
What are the benefits?
- a system with a 3000 watt boiler saves about 450 Euro / year and pays off in about 8 years (calculated for Bucharest, a family of 4 people, with a south-facing balcony, at current prices). The economy stems from two sources: firstly, the reduction in warm water waste which is an inherent problem for apartments located at higher levels in the block and are supplied from the city’s warm water network, and secondly, the decrease in electricity consumption needed to heat the electric heaters.
- no approvals are required from the electricity supplier, the town hall or the owners’ association.
- you enjoy a fast pay-off time for a photovoltaic system.
- we deliver the turnkey system.
Find out about the benefits, efficiency and prices of the system below.
Please watch the presentation film of the pilot project that forms the basis of this offer:
The main information about the system, shown in the presentation film (and many more):
- Because the resistors (boilers) work just as well in direct current (from photovoltaic windows) or alternating current (from the grid), it is not necessary to convert the current from photovoltaic windows into alternating current, as long as the need for domestic hot water is not completely covered by the photovoltaic system.
- Thus, installation and maintenance costs are minimized as the system does not require connection to the grid (off-grid) and is composed of few, cheap, reliable and easy to maintain items.
- We have been monitoring the system since February 2022 and it works flawlessly.
- If the balcony is not yet closed the photovoltaic glasses can be included directly in the double-glazed windows of the closed balcony, otherwise they can be fixed on the external side of the windows frames.
- The system is suitable to be installed in apartments, as it offers the possibility to install photovoltaic systems individually, without the need for the approval of the electricity supplier, the owners’ association or the town hall. These systems can also help meet nZEB standards that require 30% of the energy used in buildings to be from locally generated green sources, an important aspect being that photovoltaic windows filter excess solar radiation, thus increasing thermal comfort and considerably reducing the energy consumption with air conditioning in summer.
- South-facing windows have the best performance. Those oriented to the East or West generate approximately 70% of the energy of those oriented to the South. For south-facing windows the maximum yield is obtained in the cold months (except May – July) and for east or west-facing windows the maximum yield is obtained in the warm months (except November – February). Systems installed in the extreme north of the country will produce about 5% less energy than those in the extreme south.
Different configurations of photovoltaic glass + electric boiler can be calculated to optimize the energy transfer from the glass to the boiler directly. Below is a table showing the main packages available (other packages can be configured according to the particular requirements of each project):
| Volume | Heater resistance power | Number of standard PV glasses x transparency package price |
| 15L | 1200 WATT | 3 x 30% – 1300 € |
| 30L | 4 x 40% – 1500 € | |
| 50L | 1500 WATT | 3 x 10% – 1300 € |
| 4 x 30% – 1500 € | ||
| 80L | 2000 WATT | 4 X 10% – 1500 € |
| 6 x 30% – 1950 € | ||
| 7 x 40% – 2150 € | ||
| 100L | 3000 WATT | 2 x 10% + 6 x 30% – 2350 € |
| 10 x 40% – 2750 € |
| Volume | Heater resistance power | Number of standard PV glasses x transparency package price |
| 15L | 1200 WATT | 3 x 30% – 1300 € |
| 30L | 4 x 40% – 1500 € | |
| 50L | 1500 WATT | 3 x 10% – 1300 € |
| 4 x 30% – 1500 € | ||
| 80L | 2000 WATT | 4 X 10% – 1500 € |
| 6 x 30% – 1950 € | ||
| 7 x 40% – 2150 € | ||
| 100L | 3000 WATT | 2 x 10% + 6 x 30% – 2350 € |
| 10 x 40% – 2750 € |
Takeaway notes:
- Prices shown do not include VAT (5% for individuals and 19% for companies).
- Prices include materials, installation and commissioning.
- Payment can be made in 2 installments as follows: 50% at the beginning, 50% after the system has been commissioned.
- The system warranty is 5 years.
- The warranty of individual components will coincide with the producer’s warranty certificate. Photovoltaic windows have a 10 year warranty for the materials and 25 years for the power they produce (at least 80% of their power from their manufactured date after 25 years of use).
- Boiler and boiler installation are not included in the price. Indicative boiler price + installation = 200-300 Euro.
- The price includes the control sistem with automatic switch between photovoltaic and network modes (e.g. it can be scheduled to switch at sunset/sunrise or at certain hours of the day or it can be even directly switched from the mobile app). Such a system requires a working Wi-Fi connection in the apartment.
The energy generated by a 3KW package can heat a 100 L heater with 25’C about 160 times / year
(e.g. between 20’C, cold water temperature and 45’C, hot water temperature).
The energy generated by a 2KW package can heat an 80 L heater about 190 times / year with 15’C.
(e.g. between 30’C, warm water temperature and 45’C, hot water temperature).
The energy generated by a 1.5KW package can heat a 50 L heater of about 225 times / year with 15’C.
The energy generated by a 1.2KW package can heat a 30 L heater at about 150 times / year with 30’C.
The energy generated by a 1.2KW package can heat a 15 L heater at about 290 times / year with 30’C.
The above estimates are made using the European Commission’s Calculator for south-facing windows, Bucharest area.
Last but not least, this type of system is a handy solution for city dwellers who want to reduce their carbon footprint and who are concerned about protecting the environment and limiting the effects of global warming.
Video with the complete system made with 11 photovoltaic windows and 2 boilers (15L and 80L).
Video with technical details of the complete photovoltaic system (11 windows and 2 boilers).
Find out why we don’t use an invertor on our photovoltaic windows system
