Getting smart with solar energy storage

Peter Thiele, president of Sharp Energy Solutions Europe, demonstrates how solar batteries can store power for use when the sun isn’t shining.

With the right infrastructure in place in your rented property, a solar system can supply up to 80 per cent of the tenant’s energy needs. Intelligent home energy management systems, comprised of solar panels, a battery and an energy manager, mean that energy can be stored and used long after the sun has set.

Nowadays, solar panels have become fairly common and they are widely considered as a sensible investment for property owners. By adding a battery to a solar system, you can transform the amount of solar-powered energy the property consumes, which is typically 20-30 per cent a day, up to about 70-80 per cent, giving those living in the property greater independence from the grid and protection from energy price hikes.

When you are looking at solar panels, landlords need to consider power, efficiency and cell type, as well as the space available. Pmax is the power of each solar module. It is stated in Wp (watt peak) and refers to the output from the solar module electrical peak power under standard test conditions. The efficiency is the ratio of input (sun energy) to output (solar power). Normally, the module efficiency is compared; however, some manufacturers also specify the cell efficiency.

For this reason, specifiers should ensure they compare the correct values. Higher performance and greater efficiency are especially recommended when roofspace is limited.

Technologies

There are two prevailing technologies in the market: polycrystalline and monocrystalline cells. Monocrystalline cells are usually more efficient, but more expensive to manufacture, whereas polycrystalline cells can be produced more cost-effectively but have a slightly lower efficiency. Ultimately, the space available on your roof would determine which technology would be most beneficial.

Choosing a battery

When choosing a battery for your solar system, property owners need to consider its type and size. While some lead-acid batteries have been in use in the past few years, lithium-ion technology has now become the standard. The reasons for this are the smaller size and weight of lithium-ion batteries and the better usability of the capacity. This technology is also used in eCars or smartphones.

While lead-acid batteries can only be half-discharged, lithium-ion batteries have a “Depth of Discharge” of 90-95 per cent. Depth of Discharge describes how much of the total energy that the battery stores have been discharged, or can be discharged.

Landlords therefore need to take into consideration their PV system size and electricity consumption. If you look at the average PV residential installation in the UK, they are typically from 2.6 kWp (kilo watt peak) up to 4 kWp in size. For every 1 kWp installed, in the UK you’re probably going to generate around 800 – 900 kWh per year, depending on where you are in the country. The system’s capacity and power are scalable simply by connecting multiple battery storage devices or battery inverters.

Energy managers

The final part of a smart energy system is an energy manager. Energy managers allow users to see how much electricity the rooftop solar system is currently producing, feed and take from the grid, the battery charge status, and the current energy requirements of the home.

Some managers can save this data for easy evaluation on a daily, monthly or yearly basis. They can also display how much and at what time of the day selfgenerated energy is being used, as well as measuring the energy performance of the home. Some types of energy managers can also analyse how energy is used in the home and manage the energy going to household appliances automatically.

The system can receive information from different devices in the home using smart interfaces, or with the help of wireless plug sockets or relays. The devices can be turned on or off according to previously defined conditions, such as at certain times, when there is a surplus of solar power, or in a certain sequence. As an example, when using our energy manager and battery storage, properties with solar panels can generate up to 99 per cent of the electricity they need on sunny days, and up to an average of 80 per cent during the whole year.

With systems like this, consumers can reduce their electricity bill by 80 per cent during the year. A major challenge when it comes to maximising domestic consumption of self-produced solar electricity is getting around the fact that solar energy is only produced during the day, yet is increasingly required in households when the sun is no longer shining.

Controlling energy storage is a way to solve this problem and make solar energy available in the home right around the clock. There has never been a better and more important time to support solar power.

Peter Thiele is the president of Sharp Energy Solutions Europe