Off grid storage for your home

Solar panels and small wind turbines are becoming more and more popular amongst the general public as people look for alternative ways to provide electricity for their homes. They both suffer from one key disadvantage, however, in that they are both intermittent as a source of energy. This means that rather than your electricity being there when you require it, it is there when it is optimum for it to be generated.

To get around this, the electricity generated by solar or wind power can be stored in batteries. Whilst storing excess power in this way has been used in the past, due to the expense and the size of the batteries it has been more common for any excess electricity generated to be fed back into the national grid utilising what is known as a feeder tariff.

Battery technology is one of the fastest advancing fields in materials science however, the size of batteries has dropped massively in recent years as they get increasingly more efficient.

So why would you want to store your excess energy?

In 2008, the government launched The Feed-in Tariff (FiT) as a means to promote growth in the micro generation and renewables industry. This essentially guaranteed a payment for twenty years for any excess power you generated that was imported back into the grid.

When first introduced there was a massive up take, not only by individual homeowners but also by investors who went to the extent of renting roof space for solar panels from home owners as the returns were so good.

In 2015, there were substantial changes to the FiT which significantly reduced the return on exporting excess power and subsequently, as of April 1st 2019, the scheme is no longer open for new applicants.

Whilst the going was good for the feed in tariffs, especially when they were first introduced, there was no real financial incentive to store your energy as opposed to exporting it. A roof full of solar panels would pay for itself in a few years. Now however, with firstly the reduction in the feed in rate and now the closure of the scheme to new applicants, owners of existing systems and those looking to invest in them for the future need another financial incentive to warrant the investment.

Following the re-introduction of time of use tariffs off grid battery storage combined with a couple of other factors, this potentially allows for some of the financial benefit that is currently lacking. The first is the big improvement in the storage batteries themselves.

Types of renewable energy battery storage

There are currently two main types of battery used, with a potential third available in the not too distant future.

Lead Acid

This is the oldest and most affordable type of battery storage used. It looks very similar to heavy duty car batteries and in some home built storage systems that is exactly what has been used, along with marine batteries and even batteries from diesel/electric submarines.

For many years, these were the only option, they do however have some significant down sides compared to more modern solutions.

Firstly is their size, they are not particularly energy dense compared to more modern types of battery, and this combined with their weight can be significant obstacles when it comes to sighting the batteries in the first place.

Secondly is the amount of maintenance they require compared to more modern systems.

Thirdly, they have limited lifecycle compared to more modern batteries.

Lithium ion batteries (Li-ion)

These are currently the most popular amongst battery manufactures for excess energy storage. Although more expensive to purchase initially compared to lead acid batteries, they require virtually zero maintenance and have a much longer useful life.

There are other types of battery technology that are currently being researched or under development that have the potential to revolutionise the energy storage market.

Currently even Li-ion batteries have a serviceable lifespan, after a certain number of cycles the batteries will no longer be able to store and discharge energy as efficiently as they did requiring replacement. Some of the technologies currently under development will effectively have an unlimited lifespan.

Battery Management Systems

Another piece of technology that is having a positive effect on the energy storage sector is the increased use of Battery Management Systems (BMS). These systems manage how and when the energy is not only stored but also when it is used. They can choose the optimum time to either store or discharge the energy on a cost basis making the savings more effective for the owner.

Future of off grid storage

The next logical step with off grid storage involves the use of Electric Vehicles as part of your energy storage and management system. The idea behind this is that for the majority of the time your EV is not actually being driven and that once it is fully charged it is a whole load of energy sitting there not doing anything until it is next used.

The idea of using the energy stored in the car is similar to that of a battery storage system, i.e. it is used in conjunction with a BMS that will adjust where your power is coming from depending on the current cost in relation to a time of use tariff.

The biggest obstacles to the wide spread introduction of these types of systems is twofold. Firstly currently there is no widespread knowledge of these systems amongst the general public, there is no Amazon or Google of the off grid storage world pushing the concept and its advantages into both the public consciousness and that of potential installers.

Of all the systems currently on the market, the one with the biggest, or at least most recognisable brand, is Tesla’s. The biggest issue with the Tesla system at the moment is the eye watering cost for their system, which has the potential of putting people off initially. Other offerings on the market tend to be by brands that are not household names and as a result they don’t generate the awareness of their product into the public’s consciousness.

Looking forward, it is more likely to be a case of ‘when’ rather than ‘if’ that off grid storage becomes commonly utilised. Even if the actual installation of storage batteries in the home never becomes wide spread, the ongoing adoption of Electric Vehicles as people’s primary mode of transport is likely to make it a more common and viable option in the future.

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