Have you considered what set-up is right for you?  Do you need back up in case the grid fails or do you want to be completely independent of the grid?  You might be building a new property in a remote location and find that it is too expensive to get connected to the grid.  There are many things that you will have to consider before deciding which set up is right for you.   Below we will discuss both types of setup to help you decide.

OFF GRID system

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With an off-grid system, you are completely reliant on solar energy produced by the sun, this energy is then stored in batteries which you can use to power every day items in your home. You are completely independent of the grid.  Whether you live in a house, boat or converted vehicle anyone can live independently of the grid with an off grid setup. The sun has an ifinate supply of renewable green energy and the solar power that shines on the earths surface every day is more than enought to power the worlds energy requirments. 

 

Energy Consumption

When designing your off grid 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. So a 12v system that has a current of 400amps will have huge cables isolators and fuses which are expensive and more difficult to install, by running the same system on 48v the current will only be 100amps so the cable, isolators and fuses can be smaller which will be a cost saving. Also the conversion from 48v to 240v is smaller than 12v to 240v so typically inverter chargers are cheaper as the transformers are smaller. Below are some examples of some different systems that use different voltages but remember it all depends on what you want to power as to the size voltage of your system.

What is the best voltage for your system?

12v

12v systems are commonly used in camper conversions and small off grid buildings with small PV arrays.

24v

24v systems are often used in truck conversions, marine applications such as canal boats and slightly larger off grid buildings with a medium size PV array

48v

48v systems are used in off grid houses, energy storage systems, larger vehicle conversions and boats and commercial buildings.

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.

Grid Tied system

If you are considering a grid tied system it is important to know that if your system 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.

Other things to think about for both types of systems

When installing solar panels onto strings whether it be an MPPT or an AC string inverter they must all be facing in the same direction and be of equal size, make and type. The optimum direction and angle is due south with a 30 degree angle. If you have solar panels that are different sizes or directions then it is recommended that they go on separate string inverters, MPPT’s or optimisers so that they can be managed individually.