Off Grid Systems

Callidus provides full electrical off-grid solar and battery systems, for the smallest stable to the largest house or business. Whether it's an existing building, a new build design or Class Q permitted development planning application. We will fully support you every step of the way. We take care to ensure that your system design is fit for your requirements so that your equipment produces the power you need when you need it. We do this by gathering the information from you at the beginning of the process, to understand your requirements. We build our system to be fully expandable, and system components can be added to/expanded to meet your growth. The off-grid systems we design and build are always based around the customer's needs and requirements, to ensure that your off-grid living is as carefree as possible. We only use Victron equipment on our builds; this is because they have a 45-year heritage in manufacturing quality equipment for the off-grid, Marine, Emergency Services, Armed Forces, plus many more.

Callidus engineers/electricians are fully trained Victron engineers, and we have invested time in the quality training from Victron to ensure we provide you with the correct product for your needs.

All of our off grid solar and battery power systems are built with the following 6 points in mind:

  • Quality of the off grid victron equipment and high installation standards .
  • All of our systems are built to last the test of time by using victron's quality product.
  • We can fully trust the off grid equipment that we are designing and installing.
  • Victron off grid battery and solar systems ensure all of its materials are built to the highest standards to ensure that it doesn't just meet a requirement; it exceeds it.
  • Victron equipment has been in the field for 45 years and subjected to the harshest environments & conditions.
  • The Victron system offers a fantastic remote monitoring platform that not only gives you a complete overview of your system but also allows it to be controlled from anywhere in the world if you need support from Callidus or Victron.

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Ease of Use

It is absolutely essential our systems are simple to use, and that you the customer should be able to use the system easily. We design our systems to need as little human interaction as possible. Built into the design is the integration of remote monitoring and full control; this can be accessed by the use of smartphone, tablet or computer. This adds an essential dimension of control, enabling you to view your system performance from your armchair and even turn things like generators on remotely.


Our systems are designed for efficiency and making the best use of all available renewable energy on the site, be it the sun, wind or water. This renewable power is charged into batteries efficiently to ensure that you achieve the maximum conversion of power into a useful energy source for your home or business.

Smart Design

How many batteries and solar panels you will need will depend on what your energy needs are on site. One size doesn't fit all. We use sophisticated software to design your system to ensure it delivers power all year round in line with your expectations. All systems we build are expandable, so if you require more power or your needs change you can simply add an extra battery, Solar PV Panels or an inverter to boost your power supply, meaning you can build a modular system at your pace or when budgets will allow.

We pre-build all our Off-Grid systems in a controlled environment; this is to ensure that we maintain the highest quality and build standards possible. Every system is electrically tested, load tested, commissioned and updated before being installed at your premises.


The system will be fully explained, demonstrated and handed over to you by the engineer on the day of commissioning. However, in the first few weeks, you will be getting to know your system, and you will be curious about what your system is doing. We are here to support that, we offer support via the phone, or we can log on to your system remotely to take full control of it, make and updates or changes as required. 98% of the time remote support is more than adequate. However, onsite help is also available offered if needed; a site visit is available at an additional cost.

System Design

Your system has been designed with a 5000VA inverter charger and Victron MPPT and 6 kW of Solar panels. This is to provide a hands-off with an auto-start relay for a generator, off-grid power supply that is as close to having the mains as is possible. This is done by using the latest high power output solar panels offering a life expectancy of between 35-40 years and a performance warranty of 25 years. Secondly, we use a tried and tested lithium battery pack that offers up to 6000 cycles @80% Depth of discharge, which offers an extended 10-year warranty. This is topped with a fantastic control system that will allow you to control your system anywhere in the world (internet connection required).

This system is designed to offer 5000 kWh a year; the inverter offers 4.4 kW of inverter power rated at 10kw of peak loads for a few seconds and 9.6 kWh's of battery storage. During the summer months and in Spring and early Autumn you can expect to get a good amount of your energy requirements from your solar and batteries and as it gets darker and colder you will need to use your generator.

The purpose of the generator on our Off-grid installation is to charge the batteries via the Charger and the inverter to power your property, ideally not for the generator to power your home directly. By charging the batteries via the generator rather than running the generator full time, will reduce the fuel usage and maintenance. A generator running 24 hrs a day with a small load only does damage to the generator, but it will burn 1 -1.5 litres an hour equalling from 24-36 litres a day. The generator will automatically come on when required to charge the batteries when they are low or to offer additional short-term power to the house at times of peak demand. This is done automatically when the management system detects a need.

The table below shows the savings froms just using a genartor 24 hours aday to using a genartor with battery storage

If you're looking to run large loads for extended periods, such as electric heating, then a 1500 rpm unit is recommended as it's designed to run for far more extended periods. Please ensure the generator has enough Kw output for your requirements. Where possible its always best to look at other forms of heating, other than electrical when off-grid, as your generator is likely to run for longer. LPG, oil or wood burners may be a good alternative.

A 3000 rpm generator is considered a backup generator and isn’t ideal for running full time. Therefore we need to look at the 1500 rpm unit if you have higher usage. We are happy to help you with your selection of a generator. However, we are more than happy for you to purchase your own generator and connect it to our system.

Choosing the correct generator for your needs is vital, and the right unit will make a difference to your off-grid living and experience.

Below are what technologies will be powering your home

You will need to be happy with the delivery capabilities and limitations of the system to ensure this meets your requirements. By looking at the graphic above this can be easily checked by looking at the electrical equipment you want to use at your home and then considering what equipment can be used and when, i.e. how many kw's will you need to cover your peak load.

It is always worth looking at different products with lower peak energy demands such as changing from 3kw kettle to a 1kw kettle. The kettle is the most frequently used high demand electrical products in the home, then looking at what your dishwasher and washing machine will use and for how long and what draw they have. The simple rule of thumb is that the higher your peak energy requirement, the more batteries and inverters you will need and the higher the overall system cost will be. If you can reduce your peak power requirements and spread it over a more extended period, the cheaper the equipment cost will be.

The below graph shows the estimated generation and usage of your system. These have been designed around 5000kWh and 4kW of peak use and the first graph shows the usage for a year and the other per typical winters day.

Off Grid Case Studies

Cornwall off grid solar and lithium battery

Cornwall off grid solar and lithium battery View Details »

Norfolk off grid solar and battery

Norfolk off grid solar and battery View Details »

New build off grid home in somerset

New build off grid home in somerset View Details »

What our clients say

Brillant product,excellent communication with Steve , first-class installers. Would definitely recommend

Tosh Abbott, Dorset

Such a great team, James done a great job specifying what I needed and a very non pushy approach, all done at my pace, great site survey by Steve who explained what I was getting and why I needed certain things, Ross and Brian done a very tidy install and was a pleasure to have them on site working. They worked hard and got the job done to a very high standard, even answered my questions and explained how the system work. Thanks guys highly recommend!

Mark Cannings, Wiltshire

We live off grid in Cumbria and wanted to upgrade our electricity supply. We contacted Callidus and they were very happy to work with us. With excellent two way communication, they designed the perfect system for us which is easily expandable if we should need it in the future. They were happy to design the system and supply us the parts for us to install ourselves. They programmed the system and were on the end of the phone to help with installation and getting the system up and running. Their after sales service is excellent. It has improved our quality of life no end.

Jack Beach, Cumbria

I found Callidus on Facebook and initially worried about using a company I knew nothing about for such a financial investment and being off-grid we had no mains electric to fall back on. However, there was no need to worry as Callidus have been professional from start to finish. Designing a solar system for our rural property, their customer service has been fantastic. From James and Steven initially advising on the system package, then Brian and Ross installing with expertise and precision, their attention to detail and quality of work has been excellent. I cannot thank Callidus enough for our solar electricity, truly improving our quality of life and home comfort.

Kerri Featherstone , Durham