Let us talk about battery storage

With the recent DECC review proposing colossal cuts to the FiT in UK and other European Union countries in 2016, many have concerns about where that will leave the PV industry. Will the market drop? Will new technologies reinvigorate it?

Whilst many are focusing on the current installation rush, it’s important to consider what revolutionary technologies might emerge in 2016.

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Feeding the grid for the FiT

Previously, self-consumption has not been a priority – Why is it more important to maximize what’s used on site now?

With the threat of a huge degression in the New Year, generation FiT just won’t be worth as much and PV systems will take longer to reach financial payback without users getting energy smart and using all the available units of electricity on site. Battery back-up is a great way of aligning the available PV generation with the consumption profile of the building.

Is Battery Storage A Saviour?

One of the key interests right now is battery storage, but with so many products available and different types of technology, it’s easy to feel dazed.

Whilst it’s not a new notion, battery storage may yet make a big impact on the market so it’s important to know the in’s and out’s so you are ready to make that big pitch to your customers.

What Types Of Battery Are Available?

There are two main types of battery that will be used with PV systems: Lithium Ion and Lead Acid.

Lithium Ion (or Li-Ion) batteries are typically quicker to charge, have a higher depth of discharge and have a longer life.

Lead Acid batteries are more likely to need replacing sooner but are a lower initial cost.

When comparing the two options, you need to compare two batteries with the same actual/available kWh – not the listed kWh size.

System Types

We have identified some key system types, see below for more information:

DC side storage device, Growatt SP range:

A DC storage device, such as the Growatt SP range, is a charge controller that is added to the DC strings. The controller constantly monitors the demands in the building and either lets the energy through to the inverter (where it is converted to AC as normal), or diverts it to the battery if the energy isn’t needed in the building at that time. Once the demands in the building are greater than the available PV generation, the battery will start to discharge.

• This type of battery system can be retro-fitted easily to an existing PV system.
• It will work with almost any type of PV inverter.
• DC to DC conversion (from controller to battery and back) losses must be taken into account. The amount of energy going through the generation meter will be lower. The upside is the energy is available at any time, so can reduce the need to import from the grid.
• If the battery is fully charged, and there’s no demand for PV power in the building, it will be exported to the grid as normal.
• This battery system works through the standard PV inverter, so it will not help in the event of a power failure.
• The charge controller is single MPPT, so can only work with DC strings from one roof elevation.

DC side hybrid inverter: GoodWe Hybrids & Hoppecke Battery

Another DC side system: in this case, the charge controller and inverter are contained in the same unit. The hybrid inverter monitors the consumption in the building and either diverts power to the battery if it’s not needed, or converts it straight to AC if there’s a demand for it.

• This type of system includes an inverter, so it cannot be retro-fitted to an existing system.
• The hybrid inverter must conform to local grid connection regs.
• The battery being used must be compatible with the hybrid inverter.
• The hybrid inverter can be dual MPPT, so it can work with more than one roof elevation.
• The hybrid inverter can be set to work in island mode, so that it continues working in the event of power failure.

StorEdge/Tesla DC side battery backup:

Let’s talk about battery storage

StorEdge from SolarEdge is a DC side system for diverting excess power to a battery. It is initially being marketed in conjunction with the Tesla Powerwall. The overall pros and cons are the same as a hybrid inverter. Let s talk about battery storage

• Must be used with a single phase SolarEdge inverter.
• Must comply with standard grid regulations.
• Can be set to control export with the meter.
• Large battery capacity means that the largest single phase inverter possible should be used.
• The SolarEdge optimiser functionality means that all roof areas can provide power to the battery.

Click here to see all battery storage options on the portal >>