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Will Darby, managing director of Carlo Gavazzi UK, looks at the developments in the solar PV market and how these technologies are changing the market.
Remember when the financial sections of the weekend’s papers were full of stories about how much money there was to be made by installing solar panels on your roof? You could be forgiven for thinking that solar PV was dead and buried given the lack of interest nowadays. Not so. The domestic feeding frenzy has undoubtedly tailed off, but there’s still a healthy market out there if you know where to look.
Now the incentives on offer by the government’s Feed-in Tariffs (FIT) have dwindled, the argument for the technology is less about making money and more about how much energy can be saved, fuel bills cut and carbon emissions reduced.
The solar PV market may no longer be a licence to print money, but the technology’s ability to deliver on energy reduction means there’s still a healthy commercial market. Indeed, the availability of affordable solar battery storage technology, coupled with tumbling equipment and installation costs for the PV panels, is breathing new life into the sector.
An average household, school or business will not use all of the energy created by their solar panels over the course of a day which means that the excess needs to be sold back to the grid. With reduced FIT available from the government, this is no longer as attractive as it once was. Solar battery storage works by taking the excess solar power created by the panels and using it to charge the battery during the day. The battery can then supply energy to the property during the evening and on cloudy days on the excess supply.
Battery storage applications for solar PV come in all shapes and sizes, from the home to the industrial scale. The London Borough of Hounslow is an early adopter, employing the technology at the massive solar scheme at the Western International Market. The vast array of more than 6,000 solar panels on the rooftop of the wholesale market for fresh produce and flowers is said to be the largest such array put up by a local authority. Hounslow’s £2 million investment in solar is also the first by a council to adopt battery storage to maximise the power from the panels.
The 1.73 MW array of 6,069 panels and four 60kW lithium batteries now generates half the site’s required electricity and Hounslow council, which owns the market near Heathrow Airport, says the solar system will contribute 2% of its carbon reduction target, cutting emissions by more than 780 tonnes a year. It will also save £148,000 in energy costs which, along with £100,000 in generation tariff payments and £7,000 in export tariffs, means that the council expects to be £255,000 better off in the first year of operation. Not only can it expect to see immediate savings on its electricity bills, but it is anticipating a return on investment in about five years.
According to a report on renewable energy investment from independent energy firm Smartest Energy, some 2.3GW of battery storage, via 150 projects, is now in planning. The solar battery market is rapidly growing as more manufacturers start looking at ways to innovate and drive down costs.
Metering is an essential part of any battery storage installation and Carlo Gavazzi is receiving a significant upsurge in interest. Solar PV panels generate direct current (DC) and an inverter is needed to convert this DC to alternating current (AC). A generation meter is required to record the kWh generated and used in the home or business or is exported to the grid.
The batteries in a solar PV storage system work like any rechargeable battery: they charge using direct current (DC) from an external source (the solar PV system) and discharge DC when energy is required. DC also has to be converted to AC by an inverter. The meter is used to measure export/import so the system knows when to charge/discharge the battery in order to increase self-sufficiency.
There are two main ways of linking battery storage into a solar PV system and useful guidance is available from the Building Research Establishment (BRE) and others:
• DC coupled: the batteries are installed on the same side of the inverter as the solar PV panels; they charge from the panels, and their DC is only converted to AC when it’s used
• AC coupled: the batteries are installed on the grid-side, where the solar PV’s DC has already been converted to AC. A separate inverter converts the AC back to DC for storing in the battery. When the battery discharges, the same separate inverter converts the DC back to AC.
An AC-coupled system is more appropriate when adding battery storage to an existing solar PV system and in such retrofit applications the installer will need to verify that the new equipment being installed is compatible with the existing equipment, says the BRE.
New projects tend to be DC-coupled, but there are some important considerations. Many DC-coupled systems will not operate in a power-cut and they may affect FIT income. In DC-coupled battery storage systems, the solar electricity that goes to charge the batteries isn’t registered by the generation meter at the time, but only when it is subsequently discharged by the batteries or when the batteries are full. Since all batteries lose energy in the charge-discharge cycle, some of the original solar PV output will be lost in the process. This will impact on FIT payments. However, the savings available through buying less electricity will still be significantly greater than the loss of export tariff, claims the BRE.
From grid-connected energy storage such as E.ON’s £4 million facility, located at Willenhall substation near Wolverhampton, through to the likes of Tesla and Nissan’s products for the domestic sector, this is a market set to soar. Energy managers are advised to make sure they’re a part of it.
About the author:
Will lives in Leeds with his family and has been with Carlo Gavazzi for over 9 years. As a keen sportsman and when not playing golf, Will can be found watching various sports especially football, cricket and golf; and if he’s not at home, you might just spot him at Guiseley AFC/CC!
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