Where Space Design see the future of renewable energy in the home Solar Panels Solar panels will be the main source of future household renewables - but they still have a long way to go to be practical for the dream of off-grid homeowners. Its technology is still in its infancy in relation to complete off-grid independence. The majority of London consists of old houses and high property prices which has created a trend for loft conversions. This trend and generally unconventional roof details, such as dormer windows and orientation, has meant solar panelling to be unpractical and inefficient. Solar panels currently made of silicon offers low efficiency and high cost to the consumer. The future will see perovskite solar cells become the household standard as they are much cheaper to produce. Silicon cells capture the light at slightly different wave lengths than perovskite material which offers the potential of coupling both systems in the future with the likes of Oxford University already founding a commercial venture to capitalise on this technology. This drive in efficiencies in solar technology will allow for condensed units covering less square meterage and the potential of fully automated tracking solar panels/dishes for the household market. Battery Storage The technology of battery storage is adaptable and future proof. They are able to be used with or without solar panels as a tool to store energy. As well as storing the suns energy it can also draw electricity from the grid at night making full use of the current economy 7 tariffs. The batteries are interchangeable and will need replacing every 5-13 years which will allow future efficiencies in technology to lower the need of grid electricity. Thanks to car companies who are pioneering advances in battery technology and conversion units we are now in the position to convert AC electricity (the grid) to DC electricity (battery storage). This breakthrough in conversion units has made battery storage of household energy practical and made the future for becoming independent of grid electricity possible.
Solar Energy and the future of battery storage Household electricity in the UK is currently averaging 3,940kWh per home a year which is about 20% higher than the global average for electrified homes. Compared to other OECD (Organisation for Economic Cooperation and Development) countries, electricity in the UK is not that high compared to America averaging 12,300kWh for example. 5000 4000 3000 2000 1000 0 Annual Electricty by dwelling type (kwh/year) Figures include all uses electricity with the exception of space heating 2779 2829 3442 3847 3866 4153 Annual Electricty by dwelling type (kwh/year) Currently solar panels create free electricity as it is being generated, however if the home owner requires power at night, which is the peak time for usage, the energy is drawn from the National Grid and bought in at the energy suppliers rate. Demand from energy suppliers during peak times is met by a minute by minute tracking of our consumption and reacting to this by turning up or down output from energy stations. Spikes in energy relies on drawing instant energy from hydro or gas fired power stations and they are paid a special premium for this. Hence, higher prices at peak times for the consumer. Currently households save 50% on energy bills by using solar panels but this figure could be increased to 70-85% (1) if a battery system is incorporated. A household system will be able to sell back their energy at these peak times using battery storage. Battery units typically last for 15 years and there are currently two battery options available: Lead Acid these batteries require replacing every 5-7 years and provide a low up-front cost with the possibility of upgrading to Lithium-ion. Lithium-ion these batteries require replacing every 11-13 years. Lithium-ion battery technology forecast to fall dramatically in cost over the next five years as well as increase in capacity. At an atomic level lithium is the lightest metal and therefore became the perfect material to use as an efficient battery. Crucially for battery chemistry it easily loses an electron to become a positively charged ion.
The actual usable capacity which is more often than not measured in kilowatt-hours (kwh) may be different from the nominal capacity. This is because depth of discharge (DoD) limitations takes into account degradation by factoring the number of charge and discharges as well as the depth of discharge which both gradually reduce the batteries ability to store. This article only concentrates on DoD figures. A significant benefit of using a battery storage system is that they are able to charge directly from the grid, which means it can store cheap electricity using time-of-use-tariffs such as Economy 7. Storing direct power from sunlight creates a saving of up to 20% on bills coupled with the benefit of time-of-use-tariffs adding a further saving of 10-15%. The Department of Energy & Climate Change (DECC) announced in December 2015 that it would investigate barriers to the roll-out of smart tariff technologies. When new smart tariffs are introduced in the future the savings from cheap electricity from the grid will be much larger. In today s market to fully maximise the benefits of battery storage an ideal scenario of low energy use during the day and a spike of use at night is required. Exsting Solar and New Solar Comparing the two types of battery installation
The new solar diagram above depicts an all in one hybrid inverter, battery management and energy storage powering the home. Some systems are able to generate 4kWh to 13Wh and it allows you to store solar energy that you generate during the day for use in the evening. The idea with these products is self-consumption and the smart box is in effect a gateway. The system senses it has solar energy which triggers the smart box to run specific use cases with other loads in the home. An example would be a direct feed to an electric car charger. When the gateway recognises there is excess solar energy it is able to trigger the vehicle charging station to run with the extra solar energy as oppose to return it to the grid. How much storage would you need is a question most will be unsure how to calculate. Batteries have two key parameters: power and energy. Power being the strength to deliver and energy being the fuel to carry out the task. Starting with the power In most cases you should size the power of your battery pack similar to your solar panels (if you have a 6kW soalr system a 6kW battery is required). It must have enough capacity to take on your solar generation otherwise it will have to dump it onto the grid. Energy The pinnacle is to never let your solar generation go to the grid which means you would have to cover for the summer peak. But sizing for summer will mean you will struggle to fill the battery in winter. Conversely if you size for winter your battery will not be able to store all the solar generation and off load most to the grid. Sizing the energy is up to the consumer but many will take an average and size it for spring which is most common in the UK. For an excellent solar calculator by the National Renewable Energy Laboratory follow this link Solar Panels Solar panels are the key component to any solar photovoltaic system. The process of converting light (photons) to electricity (voltage) is called the solar photovoltaic (PV) effect. Photovoltaic solar cells convert sunlight directly into solar power (electricity). They use thin layers of semi-conducting material that is charged differently between the top and bottom layers. The semi-conducting material can be encased between a sheet of glass and or a polymer resin. There are three types of mounting you can go for to maximise the amount of light they receive: Fixed Solar Array Mounting The simplest mounting system which is the most popular currently for the both domestic and commercial sector. The panels do not move and so to ensure maximising the sunlight they should face the equator. However as most are currently placed on the most convenient facing roof face in the household market they are limited in efficiency. Manually Adjustable Solar Mounting - These can be manually manipulated during the year to adjust for the changes in seasons. Highest in the summer and lowest during winter would provide the best angle to avoid reflection. Fully Automated Tracking Solar Mounting These are the most complex as they are made to track the sun. This ensures at all times the angle of the solar array is maximising sunlight. Most complex equates to most expensive, as they are continuously moving but they are by far the most efficient. By maintaining consistent direct exposure from the sun to the module, trackers can improve a PV systems output by up to 40% compared to a fixed solar array mount. In order for a tracker system to become economically viable, the increased energy harvest must exceed the added cost of installing and maintaining trackers over the lifetime of the system.
Conclusion One day in the future we will be buying homes with listings stating batteries not included! Kobad Bhavnagri, Bloomberg New Energy Finance, predicts the uptake of batteries will be slow to start and mainly concentrated to technology enthusiasts. But by 2020 prices will have come down and grid supplied energy charges will have gone up to the point where batteries really start to become mainstream. Couple this scenario with the possibility of future government specific subsidies for homeowners we are able to see why so many large companies are exploring this new technology. Battery storage can help manage one of the key ingredients of the switch to renewable power. As more renewables come into the system, that influx of intermittent power makes grid management ever more complex. South Australia has had days where the entire state produces more renewable energy by wind than people are consuming. This is one of the reasons the South Australian government are subsidising batteries. Batteries and other forms of storage are the missing link. They can smooth out the grid, store excess power and rapidly release power when needed. This is why batteries are predicted to change our world. This is part of the revolution that will see renewable power become 24 hour power. (1) Powervault s calculations Caroline Wood (Business Development Associate)