What do the P1 -Meter graphs in the app mean?

With the P1-Meter, you can easily track how and where you use energy in your home and make changes to reduce usage. Then, of course, it’s helpful to know what the graphs in the accompanying app mean.

Supply / return per day
The examples below involve a home with solar panels. The energy price for both delivery and return delivery is set at €0.25 per kWh. This can be seen in the top left of the images below. In purple is the delivery of kWh for that day. In green, it is the supply of solar energy back to the grid. The app that accompanies the P1 meter calculates what that day’s energy costs or yields. This is also shown in the upper left corner of the image.

Below are four examples.

Example 1: basic consumption over a day

The image above shows the basic consumption between 00:00-07:00 and after 22:00; that is refrigerators, freezers, central heating pumps and standby consumption of, for example, a TV or an appliance on the charger. At 07:15, a peak can be seen from a kettle. At about 10:00 a.m. the sun hits the solar panels and is delivered back to the grid (the green line). At 11:00 another appliance turns on that requires more power than is supplied by the solar panels. By 6:00 p.m. electric cooking is going on. After that, peaks can be seen from a washing machine and dryer.

Example 2: solar energy
The image below shows a beautiful sunny day. Because there are trees in front of the panels, a ‘ragged’ graph is created. Again, a large ‘wax peak’ in the evening is visible.

Example 3: distorted image due to scaling
The image below shows a good example of a distorted picture. The zoomed-in graph makes the electricity demand look enormously erratic, but this is because the scale in the graph is twice as small as the previous example. Example two shows +2000 on the right, while example three shows +1000 here. So the graph is zoomed in more, making the differences appear larger. It is important to keep an eye on the scaling; the app itself divides the graph, so one day may appear violent in terms of peaks while little energy was used.

Example 4: saving on energy through current insight

Selecting “Now” at the bottom of the app will create a live profile of consumption or generation. The base load above is about 1,200 watts. By turning on a device, in this case a halogen lamp, we see the consumption go up. After about 10 seconds the lamp is off again, from the graph we can see how much power the lamp requires; +/- 1,550 minus 1,250 = 300 Watts. On average, a lamp is on for about 1,000 hours a year in the living room. This lamp consumes 300 kWh per year of electricity, which costs €75 each year. By replacing this bulb with a 20 watt LED bulb, which produces the same amount of light, the cost goes down to €5.00 per year. By looking at electrical appliances in this way, a lot of money can be saved.