TESLA Battery storage

There are many benefits of installing a solar battery. The economic benefits include load shifting, where an organisation can draw battery power during times of high Triad (TNUOS) charges between 4pm and 7pm during winter rather than drawing expensive grid energy.  A company can also reduce the peak load that it may draw, in order to stay below a physical or financial threshold that may be imposed by their supplier. Large pieces of industrial machinery may have this effect. A pre-charged battery can provide this energy to smooth out the spikes, without drawing high peaks from the local network. The third benefit is to act as a store for renewable energy generated on site as the battery could be charged off free solar electricity. This energy could be sold back to the grid for a nominal sum, or retained to replace future demand.

Connecting a battery to an organisation’s electrical infrastructure is done in the same way as EvoEnergy connects a large solar PV array. We generally connect the battery to the primary distribution network and ensure that the organisation’s protection systems are up to date and will behave in a known way in the event of a problem. The batteries deliver a direct current (DC) and this is passed through an inverter to create alternating current (AC) which is suitable for general use. In addition to the battery and inverters, EvoEnergy will also install a G59 relay and cut-out to protect the site in the event of an electrical failure, in addition to a series of meters to ensure that the billing and flow of energy is understood. This generally requires significant design and customers can ask iGen to investigate old infrastructure thoroughly to give them a better understanding of the risks within their systems.

Capacity is the total amount of energy in kWh (units) that a battery is capable of storing. Batteries should never be drained completely, however  some are misleadingly sold quoting ‘total’ capacity. It is important to check what’s being stated. ‘Useable capacity’ is the key figure you need to know. For example although a Tesla Powerwall 2 is 14kWh, it’s sold as 13.5kWh, it’s useable capacity. It will not fully discharge to prevent damage to the battery cells.

There are two main types available:

• Lead Acid
• Lithium

Lead Acid is very cheap to install but it’s inefficient and won’t last for a longtime.  For this reason Lead Acid has all but disappeared from the Solar Storage market.  Though the price of Lithium (ion or iron phosphate) is slightly higher, it’s much better value for money.  It will last far longer and deliver more kWhs (units) during its lifetime.

A cycle is one complete discharge and one complete charge. However in reality it doesn’t happen like that. A battery may only discharge 25%, then recharge 25%. This would be a quarter of a cycle. So you need to know how many cycles a battery is warrantied for. Only then can you work out how many kWhs (units of electric) your battery will deliver over its entire warrantied lifetime.

Some battery storage systems only deliver 800w (watts) of power. No good if you want a cup of tea (your kettle needs 2000 watts).  Likewise, if you’re generating 4kW but the battery can only take on 3kW then 1kW will be heading to the grid, wasting your precious free energy.

So it’s important that you check the power output before you buy, otherwise you may find yourself drawing a lot of energy from the grid even though you have energy in your battery.

Grid services are the portion of services that are devoted to supporting the National Grid. They change from time to time as the National Grid seek to manage their network more effectively. They appear as short term markets with bidding opportunities, barriers to entry and licences. These services can be accessed from inside an occupier’s property as well as connected directly to the grid. The services typically are designed to provide additional grid stability at short notice; should an unexpected event occur on the network outside of its normal operation. By allowing your battery to be entered into these network managed markets – making your asset available to the network operator – additional revenues will be earned.

A grid connected battery is one that is connected straight to the electricity grid and derives its income solely from providing grid services to the National Grid. A “behind the meter” battery is a battery that is connected to a private electrical infrastructure, often within a factory or warehouse. In this scenario a battery can provide grid services, as a grid connected battery, and also support the occupier with load shifting, electrical storage and peak shaving services.