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Battery Storage

Customers are becoming increasingly aware of their energy costs and are looking at cost-effective solutions to not only make savings but to minimise their reliance on the grid.

Solar storage benefits include:

    • Power when you need it – make sure the energy they generate is the energy they use. A battery will
      store energy the PV system generates throughout the day, for use when they get home from work or
      once the sun’s gone down
    • Energy security – ensures they still have access to electricity even if the grid is down
    • Lower energy bills – timely use of PV generate energy means homes will be drawing less electricity
      from the grid, protecting them from rising energy prices
    • Environmental – energy generated using photovoltaic technology creates less pollution than fossil
      fuels during their comparative lifetime uses
    • Visibility – energy consumption monitoring allows end users to see where and how much they could
    • Future proofing – as we start to see the introduction of electric vehicles, future proof your home to
      ensure its ready to cope with new technologies.

We have pulled together a comprehensive Battery Storage Guide to help with you size and select the most suitable storage solution for your project.

Types of Storage System

DC Coupled

DC coupled storage is connected on the DC side of a PV system, directly between the PV modules and the inverter’s DC input. These types of systems monitor energy levels within the household and will use surplus energy to recharge the batteries during the day and discharge them during periods when energy consumption levels are higher than energy production levels. When planning a DC coupled storage system extra care should be taken to ensure the storage inverter and the PV inverter are suitable to be installed together. However, in terms of the application process this is actually quite straight forward. As the storage system is downstream of the PV inverter (on the DC side), any discharged energy must pass back through that PV inverter before it can be supplied to the property. The rating of the PV inverter remains unchanged after the addition of battery storage, so this can be installed without even notifying the DNO as long as it doesn’t change the rated output of the site.

AC Coupled

AC coupled storage still utilises DC batteries, but these batteries are located on the AC aspect of the property. In this set-up a battery will be connected to an AC coupled inverter, which acts in reverse of a normal PV inverter, converting AC to DC so that it can be stored by the battery.  An AC coupled storage system can be charged directly from the grid and it can also be supported by energy being supplied from an inverter also installed on the property. Either it will charge when specified on a ‘time of use’ (TOU) basis or it will react dynamically to changing energy levels inside the property. Unfortunately due to its position within the property and the fact that the battery is connected to a whole new unit (AC charger) permission must be sought from the DNO prior to connection.

Hybrid

Hybrid inverters combine many of the advantages offered by AC and DC coupled storage to offer a solution that is both flexible and cost-effective.  A Hybrid inverter is a PV inverter and battery charger rolled into one unit. Batteries are still connected on the DC side but can be charged from the AC supply, this means there are fewer restrictions when it comes to battery sizing as there are when only working with surplus PV energy. Also, regardless of the battery capacity, your system size is determined by the rating of the PPM (power park module) or in this instance, the hybrid inverter. Similarly as to how a 4kW PV system installed on a 3.6K inverter is registered as 3.6K – the same applies to a hybrid inverter. Feasibly you could connect 4kw’s of PV and 4kw’s of storage to the same 3.6K Hybrid inverter and still remain inside of G98.

Combining an inverter and battery charger reduces the cost of equipment and labour whilst speeding up the time it takes to install. As all the processing power is taking place inside one unit there is no need to worry about compatibility between equipment, which saves one more headache during the planning stage. It’s important to remember that these devices are PV inverters first, and require PV in order to energise and operate. Additionally, if there is an existing PV system on a property looking for storage, you may have difficulty attempting to justify the removal of a working PV inverter to replace it with an equivalent Hybrid. Which is why for existing systems it may be wise to consider a retrofit, for new storage enquiries a Hybrid solution offers the most advantages.

Download our handy Battery Compatibility Chart to discover the storage solution for you.

Battery Sizing

The choice of battery type and size is not a simple decision, there are many factors to consider. We always recommend that a comparison is made and a look at the total cost over the life of the system as simply choosing the lowest initial cost option in many cases can be more expensive over the life of the system.

Considerations for battery sizing include:

    • Essential load energy usage
    • Battery operating time
    • Space available
    • Charging time and rate
    • Maximum depth of discharge

Use the Segen Battery Calculator to help find the perfect storage solution.  There is also a pre-recorded webinar available to view that walks you through it step by step.

 

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