The Benefits of Solar + Storage

The Need for Energy Storage Solutions

The amount of energy that your solar system produces varies depending on meteorological conditions. Therefore, the stability of your PV system is reliant on a secure connection to the power grid.

Grid-tied solar power systems have the capability to reduce your electricity bills as you consume the generated solar energy throughout the day. However, solar energy generation has a particular bell-shaped curve that does not match high energy consumption hours.

Fig. 1. Solar PV generation over a single day.

In other words, the solar power that is not consumed during daytime hours needs to be exported back to the grid through an energy meter under a Feed-in Tariff (FiT) or Net Metering (NEM) scheme.

Unfortunately, the compensation value for the solar energy supplied to the grid is often well below the normal electricity rate.

Therefore, the ideal solution to increase your revenue from solar is to optimize the self-consumption of your solar PV generation. This is possible by installing an Energy Storage System (ESS) to store solar power in a backup battery.

Peak-Load Shifting and Solar Storage

Almost every state across the U.S. has implemented Time of Use (ToU) tariffs (with the exception of Montana and Rhode Island). These schemes are related to different electricity rates across the day that increase or decrease in value based on the general congestion of the power grid in every instant. Generally, nighttime hours have higher electricity rates because of the elevated energy demand.

If you install a grid-tied PV system, the array will generate solar power during the day when ToU rates are low. Any excess solar energy generated by the PV system will have to be exported back to the grid at a low price. When the electrical loads start consuming energy during the night, the electricity rate will increase drastically, resulting in a much higher price for every kWh.

However, a grid-tied with battery backup system is able to store the excess solar energy generated during the day in the ESS. The extra solar power in the energy storage device will discharge overnight to avoid energy consumption during peak electricity rate hours. This effect is called peak-load shifting.

In order to have a better idea about the impact of an ESS on your electricity bill, we can consider a case study in a research paper from Sandia National Laboratories made for a commercial-scale installation in California. The case study analyzed the effects on electricity costs in two scenarios:

1. No PV system installed

2. PV system installed with ESS

The results showed that up to $68,000 in savings annually could be obtained by installing a 200kW and 1MWh energy storage system.

Fig.2 Monthly Electricity Bills with 200kW and 1MWh ESS. Source: Sandia National Laboratories

Backup Power with ESS

One of the greatest advantages of adding energy storage to solar systems is the increased independence from the grid.

Natural disasters are one of the most common causes of grid failures in power systems. Hurricanes, floods, and earthquakes can damage transmission or distribution lines in locations with difficult access, leading to long-term blackouts that can last for days or even weeks depending on the size and scope of the natural disaster. Keep in mind that grid-tied PV systems will not have any power as long as the blackout lasts: as soon as the inverter device detects the absence of the grid frequency, the inverter’s automatic switch deactivates the DC/AC signal conversion, preventing the PV system from continuing to run.

However, by installing solar PV with an energy storage system, the inverter is able to detect the absence of grid frequency, disconnect, and generate its own frequency to run the PV system and power the selected loads in off-grid mode.

The PowerPod 2 Solution

The PowerPod 2 is an all-in-one solution that provides a connection between your solar panels and your electrical loads.

PowerPod 2 – 10 kWh model

The product uses an inverter, a microcontroller, and a battery to provide a reliable and independent source of energy during a grid outage using its backup power mode. The device has been designed to automatically disconnect from the grid in a blackout event and restore power for the selected loads inside the house within seconds.

The PowerPod also has a ToU functionality that allows the batteries to recharge during the day, either using solar power or energy from the grid (when electricity rates are low) and then discharge the battery to supply the required energy when the electricity rate is higher.

When selecting an ESS, it’s important to determine if the system will be easy to install and pair with an existing solar power system that does not support energy storage. The PowerPod has been designed as a comprehensive solution that can be integrated with almost any existing solar inverter by simply using an AC coupled configuration, allowing you to easily install your own solar power battery.

These features allow for cost optimization, independence from the grid, and easy integration with any existing solar system or generator for maximum performance.