The Sunny Dishwasher

When you drive through a Bavarian village, you feel like you're in a solar power plant. Due to high subsidies in the last years, mostly every piece of roof is plated in solar panels. However, the model for the subsidies changed since 2012. Before, you were payed for feeding power into the grid. Since then, owners of solar panels get incentives for using their own produced power - or are only paid for 90% of what they produce, so using the remaining 10% is electricity for free.

The Sunny Dishwasher uses what's here at the HackTheHouse Hackaton 2015 in Berlin to use a little of that free electricity:

- We use the light sensor of the relayr Wunderbar to see how much sunshine we get. 

- We've got a BSH HomeConnect enabled dishwasher that we can start remotely.

- The NEST thermostat gives us information about whether someone's at home.

-  Arduino combined with a PIR-Sensor and a button helps out the NEST by detecting when no one is at home anymore.

How this can play out in real life looks like this:

• The dishwasher is filled in the evening so it sits around with the dirty dishes. There's enough time to wait for everyone to return in the afternoon.
• Everyone leaves home and we detect each opening of the front door. If there is no more movement inside the house after the door was opened, we know that everybody has left and can inform the NEST about it.
• Now we can wait for the sun to come out: the best time for solar power is around noon. Once there is enough sunlight for a healthy output from the solar panels, we start the appliance. This is achieved by monitoring the light intensity.
• If the sun does not come out, the dishwasher needs to run when people come back home. For this, we query the NEST thermostat. It would be even better of course to start the dishwasher before someone gets home so it's done just in time. The NEST can give you that Estimated Time of Arrival (ETA) - but the API does not provide it yet it seems.