Describe how the model works, and how it could be improved.

Optimise the PV array size for the ‘stay at home’ load and no battery.
Add a 14kWh Tesla Powerwall (enter “14” in the battery size cell).
Re-optimise the PV array, then find what the battery needs to cost for this to be a sensible investment.
Repeat this process for different demand profiles, battery sizes, feed in tariffs, costs of capital and any other input assumptions you’d like to test. What do you learn about the range of costs that batteries need to get to?

Clear understanding of how the model works and its shortcomings (30%)
Design of experiments (i.e. different input assumptions) (20%)
Clear descriptions of the results (20%)
Concise understanding of the implications (20%).
Structure and references (10%)

1: One thing that should be fairly apparent is that the 14kWh battery is too big for the 15kWh average load. It would be useful to examine the question of what the appropriate battery size should be. Also, we are trying to use the model to answer a question – you can come up with the question, but it could be ‘how cheap to batteries need to be?’, or ‘how do load profiles and tariff structures impact affordability of batteries?’ or ‘is a city with good solar irradiance better for batteries?’

2: when describing the model and its pros and cons, don’t go into details about precisely how excel does the calculation. For example you could say the model determines at each time step how much power to put into the battery or onto the grid based on the output of the solar array and the state of charge of the battery.

Sample Solution