The use of solar collectors on the detached houses is a popular method of saving the heating energy since several years. Such buildings often posses a multi hipped roofs giving many possibilities for solar collectors arrangement.

An assumption that only the south slope of the roof is suitable for the collectors mounting is false for at least two reasons. First, trees or other objects surrounding the building may cast shade in such a way that the solar energy obtained on the south slope of the roof will be less than the one obtained on the other slope. Second, the habits of householders are substantial. Water heating in the cumulative tank should proceed during their absence. In this way, the water temperature wil get higher and hot water will be ready for the householders return. That will account for why sometimes it is better to choose east or west slope of the roof.

To arrange setting up of the solar collectors a detached house in the southern suburbs of Warsaw has been chosen. The area is an example of a city-limits where an urban architecture transforms to agricultural one. Only detached houses are standing here in the surroundings of trees and gardens. The investigated house has a roof build of two slopes: west-slope and east-slope. Thanks to ScanTheSun app – the eastern slope has been chosen for solar collectors arrangement with application of an additional stand.

For the collector adjustment measurement we have chosen a HTC ONE MAX handset with Android 4.4.2 system. This device disposes of well working gyroscope that makes it easier to contour the horizon shape.

In the first step of the collectors adjustment measurement a GPS sensor has been chosen to obtain the current geolocation. The geographical localization is essential since it allows ScanTheSun app for calculation of the Sun movement on the sky and evaluation of the available solar energy at the given latitude.

The investigated building stands between birch and oak trees. The trees may hinder the sunlight coming to the roof, therefore, they have to be taken into account in the collectors adjustment. We got on the roof and from that point made a contour of the trees. From now on the ScanTheSun app will find the best collectors orientation considering the shade cast by the surrounding trees.

The house has two slopes of the roof – eastern and western one, each tilted around 20 degrees to the level. By selection of the slope the total obtained solar energy as well as the hours of water heating during the day has been considered. In the particular building, the hot water consumption is the least in the forenoon. The water should be heated in the cumulative tank at that time to get high temperature. In the opposite case, the water will be heated in the afternoon during the highest hot water consumption and may not reach enough temperature. In that unfavorable adjustment, the water in the tank will stay cold after the afternoon usage and may never be warmed enough.

In the last step of the ScanTheSun app, the orientation of the solar collector is investigated. The handset has been put first on the west slope of the roof. The surrounding trees eclipse around one fifth of the available solar energy. The color map displayed on the screen shows that form the remaining energy reaching the collector only 66% will be used. Then, the handset has been put on the east slope of the roof. The obtained result turned out to be very similar. Shadow cast by the trees also consumes around one fifth of the available solar energy, and around 70% will be used form the remaining energy reaching the collector. Basing on that results only, the east slope as well as the west slope are suitable for the collectors arrangement. It turned out that the the Daily Energy Curves displayed by the ScanTheSun app presents the decisive argument for the east slope. The Daily Energy Curves show time of water heating during the day.

The solar energy reaching the collectors at both slopes of the roof is almost the same, however, the time of water heating during the day is completely different in each case. The time of water heating shown in in the Daily Energy Curves indicates that the east slope of the roof is much better for the collectors mounting than the west one.

The Daily Energy Curves for the west slope of the roof show that water in the cumulative tank will be heated from around noon up to 7pm. The use of hot water by householders at that time will prevent solar energy to cumulate in the tank and the water may never get hot enough.

The Daily Energy Curves for the east slope of the roof show that water in the cumulative tank will be heated from around 7am up to 2pm. The water will reach high temperature in the tank and will be ready for the householders return in the afternoon.

The time of water heating during the day clearly shows the east slope of the roof as optimal for the collectors mounting. An additional stand has been considered to get more solar energy. Thanks to the stand, the tilted angle of the collector is higher and around 81% of the solar energy reaching the collector can be used.

Thanks to ScanTheSun app the east slope of the roof has been selected for the collectors mounitng. To get more solar power we decided on the application of the additional stand. The Daily Energy Curves shown that the maximum cumulation of hot water in the tank will occur in the afternoon. Such a solution ensures that the water will be hot enough and will wait for the householders return. Another arrangement of the collectors will prevent the cumulation of the hot water in the tank.