Solar power station in Ruse city

Increasingly people want to reduce their dependence on energy suppliers. The number of supporters of modern technology, whose dream is to accelerate the movement of mankind to the pure future, signifficantly grows.

One of these enthusiasts has asked us to install a solar power plant on the roof of a farm building. The task was put in the following way: to use the entire roof area as efficiently as possible. For its decision, we have chosen the Panasonic Solar HIT 330 photoelectric modules with high efficiency (19.7%) and low temperature coefficient of change of power (-0.29% / ° C).

The roof has a one-sided slope with dimensions of 24.5×5.25 meters or ~ 128.6 m², azimuth 27° (at South = 0°) and angle of inclination 35°. The dimensions of each single module are 1053×1590 mm and the mounting distance between them is about 20 mm.

After discussing the possible options with the customer, we focused on the vertical layout of the modules in 3 rows of 22 pieces. Thus the width of the installation will be 22×1,053+21×0.02≈23.59 m and the height 3×1.590+2×0.02=4.81 m. The total solar installation will be 23.59×4.81 m or ~ 113.5 m², which corresponds to ~ 88% of the roof area.

If we use 66 modules of 330 Watts each, the installed DC power of the solar power plant will be 21.78 kW at peak (kWp).

The house is located near the town of Rousse and before starting work we conducted an analysis of this area to determine the potential of using solar energy.

Solargis data for the region

The most important type of insulation for photovoltaic systems is GHI — Global Horizontal Irradiation. The GHI of the Solargis data area is 1405 kWh / m² / year:

PVGIS data for the region

GHI of the region according to PVGIS data — 1480 kWh / m² / year and is distributed as follows:

GHI statistics from 2007 to 2016:

Horizon Specificity for Specified Coordinates (South = 0 °):

The blue line shows the trajectory of Sun’s motion in the sky on the day of the winter solstice, December 21, and the red line on the day of the summer solstice, June 21

Preliminary assessment of electricity generation

Taking into account the climate and isolation data, the azimuth and angle of slope of the solar modules as well as the horizon specificity for the site, the annual PVGIS module surface insulation will be 1660 kWh / m² / year and will be distributed as follows:

With such output data, the 21.78 kWp solar power plant will produce 31.7 MW of electricity per year, which will be distributed as follows:

This schedule shows the power output of the solar modules before converting it into AC. No losses in wires and inverters are taken into account here, but the average heat losses associated with solar heating during the warm season are taken into account, and this indicator is signifficantly better for Panasonic Solar than the average for the market.

Installation of the solar modules

Panasonic Solar modules are delivered to the mounting location well packed on two pallets:

NENCOM as official distributor of Panasonic Solar offers competitive prices, fast delivery, professional installation and a 25-year warranty of modules.

We have securely fastened the aluminum profile clips to the wooden beams on the roof:

On the brackets we placed aluminum profiles for mounting the photoelectric modules:

To join the photovoltaic modules with the shield, we used a special cable from the German company IBC Solar, resistant to temperature spikes and the effects of direct sunlight:

We also made lightning protection and earthing of the entire installation:

Installing and inspecting the first solar module Panasonic HIT 330:

The idle (no load) voltage exactly matches the factory performance — 69.7 B, although the insulation is now considerably less than the «standard» 1000 W / m². The whole thing is the temperature: the cooler it is, the more efficient the photoelectric modules work on.

The cold not only increases the efficiency of solar modules, but also embellishes them with patterns:

Our efficiency in the cold also proved to be higher :)

We put together 66 modules in 6 strings in 11 pieces. In each string, the modules are connected in series, providing open circuit voltage of about 770 volts:

Celebrating the last solar module:

Panasonic Solar modules not only work efficiently but also look great:

A movie about our work

We have traditionally shot a short video about our work on the site:

The first part of the project is completed. For the second part we buy inverters and lithium-ion energy storage.