## What unit of energy should we use?

To measure "energy generated" from the solar panels we should use kW, this unit will change dependent on how much sunshine comes into contact with the solar panels.

To measure "energy stored" we should use kWh, this unit will change dependent on how much energy is generated and also how many/what devices are being used.

## How much electricity does lights in a living room use?

Assuming we are only using LED bulbs we will use 10 watts as a standard power rating of each bulb for the calculations. this means for every hour a bulb is on it will consume 0.01 kWH of energy stored from the solor panels.

With the above statement and assuming a living room has 4 lights and are on for 8 hours on a typical day we can do the following calculation:

=> 4 lights * 8 hours * 10w = 320Wh per day => 320 Wh / 1000 = 0.32kWh per day.

## How much electricity does heating and cooling use?

A central air conditioner/heat pump on avarage uses 15,000W per hour or 15kW per hour.

## How much electricity does an energy efficent house use?

An avarage home in the UK uses between 2700kWh - 4200kWh per year dependent on the size of the house. We will assume our home on avarage will consume 3000kWh per year.