Solar related mini projects

Having owned a plugin hybrid car from June 2015, then having solar panels installed in November the same year, I got to thinking about how to use the two together. I bought an Optimmersion with the solar panels to divert some of the spare power into heating the water and saving some gas, but that only used a few kWh a day at most. On sunny Spring days I could get around 25kWh of energy being generated, about 8kWh would fill the car, but on bright cloudy days using the charger meant I could still pull more from the grid than I needed to. I needed to use the power generated more efficiently, delaying some activities or limiting power demand until there was surplus, or going as far as storing power for use later.

I purchased a couple of leisure batteries with a view to storing surplus power for the evenings, this was an early minor success in conjunction with an inverter and a fast switching relay controlled by an arduino nano, but it was limited to a handful of low power devices rather than the house as a whole. I only ran the batteries down to 80% of capacity in order to prolong their life as long as possible, but needed to go further as the inverter drained more throughtout the day than the devices themselves.

I read articles on the net about people building their own vehicle charging units and about how a control unit made by Mainpine provided the ability to control the current supplied to a car during charging by varying the resistance across two terminals. This was just what I needed and also took me in a direction away from interfacing directly to the Optimmersion display via a Raspberry Pi and USB to obtain real time information on power generated from the solar panels and net power being exported to / imported fom the grid, to the Open Energy Monitor project in order to develop a solution indepent of the Optimmersion hardware.

The pages within this section list related projects so far (which I doubt will ever be fully completed as there is always something to improve) and projects for the future.

Ultimately I am aiming for a system that takes care of itself, knows when it is going to be sunny, how much power can be expected at what times of the day; in order that it can charge the car, heat the water and store power as efficiently as possible. Ideally it will know how far you are likely to drive on a given day and if power is tight only give you as much charge for the car as is really needed (with a safety margin) so that it is not at the expense of heating the water or storing power for the evening. It will be able to make recommendations as to when it would be optimal to put the washing machine on in addition to other activities that consume power and can be scheduled differently.