Camper Vans

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. The sun has an infinite supply of renewable green energy and the solar power that shines on the earths surface every day is more than enough to power your energy requirements.

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.

Motorhome using solar panel to generate electricity

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.

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.
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.
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 can 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 different types of batteries such as Lead Acid (including AGM, Gel, flooded, sealed maintenance free, 2v Cells and spiral cell AGM) as well as Lithium which can come in a number of forms of chemistries (including lithium ion polymer). LiFePO4 batteries are all used in many different applications and they all vary on cycle life and quality which is usually dependant on the cost of the product. The best and most cost effective type of battery for Off-Grid 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 absorb 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 your highest loads. Therefore, it is really important that these are 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.