Electricity has become an integral part of the home garden. Can solar energy be used sensibly in the garden? And how does it work? Here you can find out how to use the power of the sun sensibly.
Table of Contents
The island system – ideal for the garden
The simplest form of using solar energy in the garden would of course be to connect it to the large photovoltaic system on the roof of your home. But what do you do if you don’t have this facility? Or if the electricity generated there is otherwise bound by a feed-in contract? Finally, the preparation of such a system for self-use of electricity means some effort, which probably doesn’t seem very profitable for your own garden.
The better solution is therefore called an “island solution”. A solar system set up as an isolated solution can easily be installed on the roof of a garage or shed, for example. Completely for your own use of the electricity generated from solar energy, you can use the integrated electricity storage with little effort to serve all the necessary points of consumption in the garden. For example, Yello Strom offers an island system in the rental version .
Dimension the solar system
The big question with this solution revolves around the correct dimensioning of the system. A simple rough calculation helps to determine the collector area that is right for you. The first question is which consumers you want to connect. The following overview will help you to roughly estimate the total consumption of an average day.
Possible consumers
Lighting:
- Garden lighting LED: 6 watts per lamp
- Winter lighting LED, for example light chain 200 lights: 20 watts
- Greenhouse lighting (plant lamp): 12 watts
Pump:
- Garden pump: 1,000 watts
- Pool pump: 500 watts
- Pond pump : 25 watts
Others:
- Greenhouse heater: 2,500 watts
- Robotic lawnmower: 2 Ah battery capacity, i.e. 40 watt hours (1 hour charging time with 40 watt charging power)
- Electric awning: around 250 watts
- Electric grill: 2,500 watts
Which devices to connect?
Of course, not all devices in the garden are worth using solar energy. Because the laying of cables involves some effort, which first has to be recovered by saving electricity costs. If you have consumers with a very low power requirement that are only used sporadically, the connection actually seems questionable. On the other hand, small consumers in the garden with long runtimes can be used economically with solar energy despite low consumption values due to the pure operating time.
As a second fact, your power supply via photovoltaics becomes safer the more regularly your consumption fails. This does not mean that only constant consumers may be connected. A battery ensures that the energy generated is stored until it is used up. However, the more constant your daily consumption is, the tighter you can tailor your collector area and thus the amount of energy generated to your needs.
A sample calculation
Considered consumers with power (Watt W), assumed running times (hours h) and total power consumption per day (Watt hours Wh)
summer
- Garden lighting, 10 pieces each 6 W, 4 h: 10 x 6 W x 4 h = 240 Wh
- Robot lawn mower, 1 piece, 1 battery charge per day = 40 Wh
- Garden pump, 1 piece, 1,000 W, 1 h: 1 x 1,000 W x 1 h = 1,000 Wh
- Pond pump, 1 piece, 25 W, 24 h: 1 x 25 W x 24 h = 600 Wh
- Pool pump, 1 piece, 500 W, 8 h: 1 x 500 W x 8 h = 4,000 Wh
- Total consumption per day: 5,880 Wh
Winter
- Comparison winter lighting: 1 piece 20 W, 12 h: 1 x 20 W x 12 h = 240 Wh
- Greenhouse lighting, 10 pieces each 12 W, 12 h: 10 x 12 W x 12 h = 1,440 Wh
- Greenhouse heater, 1 piece, 2,500 W, 24h: 1 x 2,500 W x 24 h = 60,000 Wh
- Total consumption per day: 61,680 Wh
The awning and grill were not taken into account because of the very short operating times. You quickly realize that your winter consumption is much higher than your summer consumption, since the heating in your greenhouse accounts for by far the highest output value. If you remove these from your balance sheet, you get the following values:
- Summer: 5,880 Wh
- Winter: 1.680 Wh
The photovoltaic surface
Simply consult the suppliers’ technical data sheets to get the “right” system size from your daily consumption. With around 6,000 Wh, this leads to a collector area of around 8 to 9 square meters or a daily output of around 6 to 7 kW or 6,000 to 7,000 W. Arranged on the shed roof, this results in an area of 3 by 3 meters, for example, which is no problem on common shed sizes should be accommodated.
