Description:
The ZEFNET Cloud and ZEFNET EVSEs can work together to ensure that EVSE load does not exceed solar generation. This means that you can make the claim that your chargers are solar powered! Not only are the EVSE's solar powered, but it also means the grid connection does not see this additional load, as the load is sucking up the generation being created. Because load is balanced against generation, the utility does not levy additional demand charges against the account.
There is a minimum quality of service that is provided (25% of the charger rating) in the case that there is no solar generation for a length of time. This can happen in more northern climates, MN being a good example where heavy snowfall can lead to 0kWh produced over the span of a month.
Typical demand charge savings are $1100 / year / 10kW EVSE, assuming $13/kW for demand.
Example:
Below is an example of a 4 charger installation that is synchronized against an 18kW solar installation. The dashed green line denotes the "Total Charging" load, the solid green line denotes the solar generation and the solid red line is the total amount of demand being pulled from the grid.
As can be seen above, the dashed green line stays underneath the solid green line, meaning that the EV charging load is staying under the amount of generation.
Pre-Requisites:
The ZEFNET Cloud has to be aware of the generation occurring, so it has to be setup as a data feed. The data feed can be pulled from the following systems:
- eGauge: www.egauge.net
- Maverick: http://www.mamacsys.com/maverick-sm-101-features.html
Worked Benefit:
Organizations are looking to add multiple EVSE units to their facilities. EVSE units range from 4kW - 19kW, with common power levels being 7.7kW & 10kW. Taking an example of 4 x 10kW EVSE units, the following demand charges would be:
#### BEFORE SOLAR SYNC ####
Demand Charge Rate: $13/kW
EVSE Count: 4
EVSE Power: 10kW
Yearly Demand Charge Cost = Demand Charge Rate * EVSE Count * EVSE Power * 12 Months
In this case: $13 * 4 EVSE's * 10kW * 12 Months = $6,240 demand charges per year.
#### AFTER SOLAR SYNC ####
Using ZEFNET's Solar Synchronization algorithm means that the same calculation can be taken, but we have to take into account the fact that you may have a day during the month which has zero solar production, meaning that there could be 25% of the rated power output provided by the grid, not solar, as a minimum quality of service guarantee:
Demand Charge Rate: $13/kW
EVSE Count: 4
EVSE Power: 10kW * 25%
Yearly Demand Charge Cost = Demand Charge Rate * EVSE Count * EVSE Power * 12 Months
In this case: $13 * 4 EVSE's * 10kW * 25% * 12 Months = $1,560 demand charges per year.
$4680 demand charge savings per year using ZEFNET's Solar Synchronization algorithm on 4 chargers.