Grid Tied With Storage System

Deciding on the best setup for your solar installation might seem a bit daunting. Solora Solar is your expert guide, following industry best practices and customizing each install.

The battery storage serves multiple purpose, firstly it provides backup power during power outage and blackouts. But more importantly, it allows customer to use their battery storage at peak rate hours and re-charge it from Grid when the Utilities rates are lower. This is very common solution for places where Utilities charge their customer tier rate and/or if there is a Solar export limit or if there is no net-metering option available.

There two type of Grid-tied PV system with Storage:

AC Coupled System
DC Coupled System

AC Coupled

Grid-tied inverters need the power grid to operate—they constantly sense grid voltage and frequency and will shut off if it falls out of range or in case of power outage to prevent any feedback to utility grid for safety reason.

AC coupling refers to installing the solar battery within a PV system after the inverter converts the DC solar energy into AC electricity. AC coupled systems require a dedicated battery inverter to process AC electricity to DC electricity to charge the battery. AC-coupled batteries are a new, innovative technology that offers in-depth monitoring and control of the battery system. AC-coupled systems were developed as a way for batteries to be easily added to a pre-existing solar system but can be installed at the same time as a new solar array just as easily.

In an AC coupled system, the grid-tied inverter is installed to a battery inverter and battery bank. The battery inverter provides a second power source, which effectively tricks the grid-tied inverter into staying online. This allows you to charge your batteries and run essential appliances during a power outage.

There are several inverter options to retrofit existing Grid-tied system with battery inverter such as Outback, SolArk or Schneider inverter with almost any low voltage battery bank such as Simplifi, Fortress Power and Outback batteries. These systems have additional capability of connecting to Standby Generator to charge batteries but also to provide supplemental power if there is no Solar power available.

There are some high voltages AC Coupled battery options are also available such Q-HOME ESS and Goodwee AC Coupled system and cost of these system is slightly lower both in labor and material cost since these are usually all in one system.

There are couple of other options available with AC-coupling, such as Enphase Encharge system or Tesla Powerwall. Both systems can be installed as outright new system or can be retro-fit with some existing grid-tied systems. Please check with our Sales team if your existing system can qualify for retrofit storage option.

The Enphase option is probably the simplest and straight forward system specially if customer already have an Enphase inverter grid-tied system and wants to add battery backup. The Encharge system can be added to existing Enphase system seamlessly with very few additional components.

Enphase has also recently launched a new innovative micro-inverter IQ8. This micro-inverter can work as a Grid-tied inverter, and as a battery inverter but more importantly it can also provide backup power without battery using Solar power during power outage, since this micro-inverter can create its own grid and prevent Utility feedback during power failure.

Tesla Powerwall option can work with most string inverter without additional battery inverter since battery pack has its own battery inverter, although Tesla Powerwall can have longer lead time sometime up to twelve weeks.

DC Coupled

In a DC-coupled system, the solar array is connected directly to the battery bank using Hybrid Inverter. There are several DC Coupling inverter options available such as SolarEdge Energy HUB, SolArk and SMA storage.

These systems can automatically sense if there is a power outage and create its own grid to supply the power and charge batteries during power outage with Solar and with Standby Generator.

Some of these inverters can be installed as Grid-tied inverter and add storage/batteries later such as SolArk and SolarEdge Energy HUB inverters.

We are often asked how the cost of adding a battery backup compares to non-battery options. Opting for battery backup can add about 40-50 percent to the overall cost of your solar project. This is primarily due to the cost of the battery and other necessary equipment.

While grid-tied systems with battery storage offer more flexibility, they are not without disadvantages. Charging and discharging batteries reduces the overall efficiency of the system and these systems are more complex to design and install and therefore more expensive.