A grid-tied energy storage system stores excess electricity generated from renewable energy sources, such as solar panels or wind turbines. It is designed to integrate with the electrical grid and supply power to the building or facility when the renewable energy source is not producing enough electricity. In other words, it is a system that allows you to store and use excess energy instead of sending it back to the grid. 

The main difference between off-grid and grid-tied and the most important to note if you go with a grid-tied system is that if it is going to be greater than 16A per phase then prior permission will need to be granted from the relevant District Network Operator (DNO). The DNO is responsible for distributing electricity from the National Grid to your home or business. This approval is required because the grid needs to conduct a network study to determine whether the local grid can handle the added load. Once approval is granted the setup can be very easy.

Energy Consumption

When designing your system the first thing that you need to think about is what it is that you want to power on a daily basis and how long for. We have produced a calculator that calculates the amount of energy consumption and how much battery storage you will require to store that energy that you will need to be able to run your everyday appliances.  Please contact us to go through this. 

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Energy Generation

Now you know how much energy you need each day you can now look at how many solar panels you need to generate the required amount of energy. Solar panels can be connected in a few different ways which are ‘AC connected’ on a pv string inverter connected on the AC side or ‘DC connected’ on an MPPT (maximum power point tracking) connected on the DC side to the battery.

There are a number of different solar panel calculators you can use to work out how much energy you will generate on a daily basis.  We always recommend using the manufacturers calculations where possible i.e. if you are connecting solar panels to a Victron MPPT then use the Victron MPPT Solar Calculator this will give the most accurate information.

What should I do in winter when solar is low?

Wherever you live in the world solar production will be slightly different throughout the year – in the UK winter months November December January and February the days are short and sometimes overcast which means that you will only see a small percentage of solar production from your solar panels 10% – 20% in most cases.

You need to consider what is the best option for you to cover this period and we have listed some options below.

  1. Over-Size the PV array to produce more energy in the winter time. This is very common and important if you are looking to produce all of you power from solar panels and batteries.  You can spec your system to produce and store more than a single days requirements then this can cover you for a few days in the event there is no sun the following day.
  2. Install a wind turbine.  This is a great way to generate extra power when there is no sunshine and it is usually windy in the winter time.
  3. Install a backup generator.  This is one of the most common off grid fail safe’s.  Install a generator as a back up in the event your batteries run flat and there is not enough solar power, then the generator can be configured to automatically start power the loads and charge the batteries at the same time.  Generators can be Petrol, LPG and Diesel and come in a range of sizes.  It is important that they are sized correctly for your system.

 

System voltage

System Voltage is what carries the current or power to the devices that you want to run. By raising the voltage you can lower the current which in turn means that you can carry more current across the same size cables. The other benefit of raising the voltage means that you are able to use thinner cables and smaller fuses.  Most house set-ups will be done in 48v.

Components

Solar Panels

Every install is different and there is no one fit all solution. Solar Panels vary in technology and wattages and can be configured in many different ways. Firstly you need to understand the size of the space and the measurements of the Solar Panels that you want to use. We stock a range of Solar Panels and discuss your options with you.

Charge Controller

MPPT’s (Maximum Power Point Tracking) are the best way of converting DC solar power in to your battery storage system or batteries should your budget allow. This is also one of the most efficient ways to convert solar power into stored energy that can be used later.

Batteries

There are many differnet types and chemistarys of batteries Lead acid AGM, Gel and LiFePo4 batteries are all used in many differnt applications they all vary on cycle life and qualitry which is usually dependant on the cost of the product. The best and most costeffective typwe of battery for Off gris is LiFePo4 these typically have around 3000 to 6000 cycles and will last many more years than lead and because they have very low internal resistance they absorbe and discharge the energy much faster with less losses.

Inverter Chargers

The inverter Charger is the heart of the system, this converts the DC power from the batteries to AC power that your electrical devices use and also manages you highest loads so the invertyer charger has to be sized correctly. The inverter charge will also be connected to a generator for back up situations if your system runs out of batteries then the generator can start and power the load and charge the batteries.

If you are adding an Energy Storage System (ESS) to a property that is already connected to the grid, then it is crucial that you follow the right steps, these are outlined by the Department for Business, Energy & Industrial Strategy Government Department.

1) Your installer should be appropriately registered 
2) Determine if you needy to notify the Distribution Network Operator (DNO) before or after installation
3) Ensure installation is notified with the appropriate bodies

It is the company that is responsible for bringing electricity to the property where you are installing the ESS system

DNO Map

Electricity Northwest

https://www.enwl.co.uk/get-connected/apply-for-a-new-connection/generation-and-storage/g99/

Northern Powergrid

https://www.northernpowergrid.com/asset/0/document/2030.pdf

Scottish & Southern Electricity Networks

https://www.ssen.co.uk/our-services/new-supplies/generation-connections/g98g99-generator-requirement-documents/

SP Energy Networks

https://www.spenergynetworks.co.uk/pages/g99_generator_connections.aspx

UK Power Networks

https://www.ukpowernetworks.co.uk/electricity/distribution-energy-resources/installing-large-scale-distributed-generation

Western Power Distribution

https://www.westernpower.co.uk/connections-landing/g99-connection-procedures

  • solar photovoltaic (PV)
  • heat pump
  • electric vehicle (EV) charge point
  • battery storage

Smaller Systems

You can self certify if you ESS system is up to 16A per phase, equivalent to 3.68kW, which is based on the lower of;

• the rating of the inverter (based on 230V) and

• the sum of the ratings of the PV panels, multiplied by the maximum efficiency of the inverter.

Installers can proceed to install the system and submit the relevant Engineering Recommendation (EREC) G98 application form to the DNO within 28 days of installation. The DNO will assess the notification and be in touch if submitted incorrectly.

Larger Systems

BEFORE purchasing your system we STRONGLY recommend that you make your application for approval for a grid-connected system to your local DNO.  Your installer will usually make the application for you.  This process can take between 15 – 45 days to complete.

Installers must submit the relevant Engineering Recommendation (EREC) G99 application form (or G100 if export is limited) to the DNO before installing the device to ensure safe and effective operation of the electricity network. The DNO will be in touch within 45 days for low voltage energy devices and 65 days for high voltage energy devices to approve installation or make further contact about appropriate amendments needed.

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