The smallest electrical system in Lawrence's downtown is the electrical system in one small shop or restaurant, which typically occupies one lot and is two stories tall. One lot is 25 feet wide and 120 feet deep.
Most of the downtown properties are this size. However, some are taller and/or occupy two or more lots. For one of these larger properties, scale up the values in the table below.
| Component Description | Overall Size | Noon Power | Installed Cost |
|---|---|---|---|
| PV Solar Collectors | 137 m2 panel area | +15 kW | $45,000 |
| Electrical Consumption | 274 m2 floor area | -5 kW | |
| Chilled Water Storage | 2.3 m diameter x 2.1 m high | -2 kW | $1000 |
| Battery Storage | 1.3 m x 1.0 m x 1.1 m high, 1250kg | -6 kW | $6000 |
To avoid rooftop HVAC clutter, maximize efficiency, and facilitate thermal storage, a ground-source heat pump heats and cools water for HVAC and provides free heat for domestic hot water during the cooling season. Peak electrical consumption (at 4:00 PM) is about 7.5 kW. At peak cooling load, the HVAC equipment consumes 4 kW.
At noon, the HVAC cooling equipment uses 2 kW to cool spaces and 2 kW to chill water for storage and use at a later time. Chilled-water storage between 9:00 AM and 3:00 PM stores enough cooling to provide maximum cooling for 3 evening hours. With 15% capacity factor (50% clouds), solar collectors rated at 18 kW save $3300/year.
Although the average annual price of electricity in Lawrence is $0.10/kWh, we assume $0.14/kWh because solar generation and storage provide peaking power, which is more valuable than baseload power.
The HVAC unit is a 5-ton Carrier 50YER ground-source heat pump. Chilled water is stored in a 2000 gal Westheffer tank. Electricity is stored in an 18 kWh M100 Aquion sodium-ion battery module.