As a Victron Energy distributor, Energy Monkey gets asked all the time if it is possible to live off-grid and even run a business off-grid. Our answer always is… anything is possible! There are a number of reasons why going off-grid is a good option with the ever increasing world population. Choosing to create your own clean energy and storing it. Instead of burning fossil fuels that release harmful emissions into the atmosphere is our number one favourite reason! In this article we will discuss off-grid systems and the different components available in the UK market.
What is an Off-Grid Storage System?
An off-grid system is a system that can be installed at your home or business to generate and store electricity where there is no grid connection. The energy can be used to power your electrical devices you may need to live or work and be comfortable. Most off-grid systems consist of 4 basic components which are the renewable power source, these are Solar Energy Panels or a Wind Turbine, inverter charger, battery bank and a back-up generator and all of these components can be sized individually depending on the specific needs for power.
Off-Grid Life: Electricity – working out what you need?
With every off-grid system you need to start by working out how much electricity you need each day and the best way to do this is to list each electrical device’s consumption and the time each device will run for. The best way is to convert everything into watts and watt hours and this makes more sense because when everything is measured in the same way it is easier to understand.
We have created a list of common devices and wattages that may be used and most electrical devices will have a label on them showing how much electricity they will consume. Any device that has a pump or motor will have a start up current of anywhere up to six times its nominal wattage.
We have put some example devices into our calculator which is available for anyone to download from this link. The image below shows what we have accounted for and how long each device will run for on a daily basis – you could argue that you won’t do a 2.5 hour wash each day but you may use the hoover some days that you don’t do a wash which we have left out so this builds a little redundancy.
|7x 5w Led Lights
|1x 15w USB Charger
|Extractor Fan 20w
The table gives us a number of useful pieces of information, such as;
- If you were to run all devices together at the same time we would need 3851w to power this which allows us to choose the size of the inverter charger required.
- 9630.5Wh is the amount of energy we need to produce daily to be able to use
- At 48v we need just over 200Ah of batteries to store the 9630.5Wh
It is really important when calculating your system to think about the future and anything that you might want to add in at a later date, underfloor heating, an EV charger for example. Planning for such eventualities is also a very good way to see the implications of running anything extra and the cost of this in your system. In an off-grid system it is better to have too much energy than not enough.
Choosing the best components for your off-grid system
If you are reading this you will probably be aware that we are a Victron Energy distributor and most of what we do is based on Victron Energy products, which really are the best products in the industry for building off-grid systems. Victron Energy has been producing products for off-grid systems for over 50 years.So in order to choose the best components for our example system from the table above we would spec a MultiPlus 48/5000/70-100 230V VE.Bus (PMP485021010) for the inverter charger. This will produce 4000w at 25 degrees. If you want to build in a little redundancy for the future you could look at Quattro 48/8000/110-100/100 230V VE.Bus (QUA488024000) which will produce 6500 watts.
Batteries for Off-Grid Systems
There are a whole host of different batteries available for off-grid systems which includes both lead acid and lithium. It can become very confusing for you to decide what is best especially when you may not understand the differences. Here is an explanation of the different type of batteries;
Lead Acid – this includes AGM, GEL, 2v Cell or Forklift batteries, Car batteries – they are all the same chemistry but have effectively different life cycles. Typically Lead Acid batteries can only be discharged down to 50% of their capacity and can have anything from 200 – 800 cycles. This means if cycled every day the very best batteries will last just over 2 years with the capacity shrinking every day. Also you can see in our example table we have accounted for 80% DOD and as these batteries can only use 50% of their capacity you would need twice the amount of lead batteries. Lead batteries also take around 15-20% more to charge the last stage ‘absorption’ which makes them basically 15-20% less efficient.
Lithium – there are different types of lithium such as Lithium Cobalt Manganese, Lithium Polymer, and Lithium Iron (which can come in a range of cell types like Cylindrical, Prismatic and Pouch Cells). Lithium Iron Phosphate or LiFePO4 is the safest and most efficient type of Lithium being able to use up to 90% of their capacity. You can make smaller batteries work harder in your off-grid systems, there is no ‘absorption’ stage making them super efficient. Lithium batteries have around 6000 cycles and again many manufacturers will claim more or less. This ultimately comes back to warranty terms and how much the battery will have at the end of these cycles. Typically lithium is a more expensive upfront outlay but when compared to ‘Cost per Cycle’ against Lead acid the lithium is about half the cost, lasting longer.
Managed batteries also known as Lithium CANbus batteries that communicate directly with the Victron system are the best option for off-grid systems and we would only recommend batteries that are on the ‘Approved Victron Battery’ list. In the UK our recommended product would be BSL but BYD and Pylontech are also acceptable.
It can be very tempting to consider lithium batteries that appear to be cheap and not approved by Victron. In our experience, people who buy these batteries have issues with the way they work, failures, hard to claim warranty or even worse, they can be dangerous.We would recommend the BSL 51.2v 100Ah batteries that come in a rack mounted version or a wall mountable powerwall version. These batteries have fantastic charge and discharge capabilities and are approved for use with Victron, connecting into the system with ease and showing a lot of data on the screen, they also have great warranty terms.
BSL vs Pylontech
The BSL Product is a 16 cell product that uses LiFePo4 BYD,EVE or CATEL cells with a voltage of 55v. The Pylontech product is a 15 cell lithium ion polymer battery with a voltage of 52v. The BSL battery is higher spec and 16 cells higher voltage allows you to generate more power from your Maximum Power Point Tracking (MPPT). Other advantages are that the Multiplus charges faster and even invert’s more power.. You can actually gain around 10% all round and the BSL also appears to have less issues than the Pylontech product in our experience. Basically higher DC battery voltage allows you to produce more power so a real advantage over 15 cell batteries that are typically ‘Cheaper Batteries’.
How to size the Solar array for your Off-Grid system
In an off-grid, system solar panels are connected together with a suitably sized Victron MPPT to generate energy from sunlight and convert it to DC power that can be stored in the battery bank for use later when you need it most.
What is the difference between Polycrystalline and Monocrystalline Solar Panels?
We often get asked what the difference is between Polycrystalline (Poly) and Monocrystalline (Mono) solar panels, and which are best? The answer is simple: Poly panels have blue cells that are constructed with multiple silicon crystals. Mono cells are black and are constricted with a single silicon crystal. Mono panels offer a higher efficiency and better with lower light levels however are often more expensive.
To work out the amount of panels you need in your system, we should firstly look at how much daily energy you need. In our example table this is around 7704.4Wh which includes approx 10% system losses from converting energy. Then we use the Victron MPPT calculator and input the values from the data-sheet of the panels that you want to use. In our example we will use 405W JA Solar (Triple Black) Mono Perc Panels which are fantastic all round solar panels and look particularly good also.
The images below show the data-sheet from the JA Solar 380-405w panels. Most data-sheets show a range of panels that are built in the same frame size. The other images are of the Victron MPPT calculator that has been correctly populated with the details from the data-sheet including temperature coefficients.
Temperature coefficients are really important as these values are used to work out how much the solar panel voltage will rise or fall in different temperatures and make sure the panels you have added to the calculator do not exceed the voltages for the MPPT controller.
MPPT calculation option 1
MPPT calculation option 2
In this calculation we have added x10 405w JA solar panels in a single string. The calculator shows us that the Victron SmartSolar MPPT RS 450/100-Tr (SCC145110410) is suitable for this amount of panels. Being that the voltage in minimum temperature will not exceed 407.5 volts. At the bottom of the calculator there is a graph that can be set to any country in the world. This gives you the predicted daily yield. We can use this to see whether the yield is enough to satisfy our 7704Wk or 7.7KWh.
Looking at the graph we start to generate 7.7KWh and more, from February until October when the days become shorter. The maximum here during the summer is around 12KWh worth of daily generation so this setup will have more than enough in the summer months and not quite enough during winter months.
In this calculation we have added x2 strings of 10 405w JA Solar panels in x2 strings of 10 configurations. The calculator shows again that the Victron SmartSolar MPPT RS 450/100-Tr (SCC145110410) is ideal as it has x2 isolated trackers. We can use one for each string! Because the trackers are isolated the 2 separate strings can be facing different directions. This is great if you need panels to face in an east west situation. Ultimately all facing south is best for the UK. The graph in this one shows with this many panels we can go further in the year from January until approx November time with more than 7.7KWh of energy and overproducing during the summer up to 25KWh worth of energy.
What are the other components that are required in an off-grid system and what do they do?
A GX device is a must in an off-grid system as it allows you to connect all of the devices together and allows them to communicate with each other. For instance when the can bus battery is full, it stops the MPPT or MultiPlus from charging. There are several options when adding in a GX device but we highly recommend the Cerbo GX (BPP900450100) or the all new Ekrano GX (BPP900480100).
In order to keep the install neat and tidy we also recommend the Victron Lynx Distributor (M8) (LYN060102000) which allows you to fuse each cable to a bus-bar.All of the devices need to be connected with a DC cable on the DC side. The DC cable should only be high flex multi strand or often known as welding cable and the correct sizes and fuse sizes are in the Victron manual, and we only ever recommend using the correct cable and sizes. You should never use AC cable for the DC connections as this can pose a fire risk.
Is using a Backup Generator how we fill the missing energy requirements in an Off-Grid system?
In our off-grid system a generator would be our back up energy, should we be having extra extended cloudy days during the winter months where the batteries have not charged from the sun. Expanding the sources of energy will make your system more resilient.
How does a Generator work within an Off-Grid system?
In an off-grid system there is no grid connection available – and you generate power with Solar Panels connected to an MPPT. This is then stored in the batteries. When there is not enough daylight or clear sunshine the system will use a backup generator as a lifeline to power the loads and recharge the batteries at the same time to minimise the use of the generator. This is also sometimes referred to as a hybrid system. The off-grid system will auto start the generator based on a number of conditions that can be set in the system. The most popular condition is ‘State of Charge’ (or SOC) which means when the batteries get down to the level you want the generator to kick in. This triggers the generator via a ‘Two Wire’ auto start function.
What about higher loads in Off-Grid?
You can also start the generator if there are loads higher than the inverter charger can deliver. Let’s imagine that you have a MultiPlus 48/5000/70-100 230V VE.Bus (PMP485021010) and this covers the loads all together but you have added a Hot Tub that adds 3500w to the load bringing the max load to 7851w.
The MultiPlus has a transfer switch of 50a this means that the MultiPlus can transfer 50a at 230v from the input in an off-grid system this is the generator and this is 11500w.
|Multiplus charger 70a
So the generator could deliver enough power to cover the above loads with the added hot tub and charge the batteries all at the same time which means you will reduce the run time of the generator and use less fuel.
Sizing the Generator and best type
When sizing a generator there are a few things to follow and look for so you get the best from your off-grid system.
You would never run an engine at 100% of its capability so you need to size the generator around 20% over the loads you wish to power so let say 11500w x 20% = 13800w or 14Kva to make round numbers.
The best type of generator would be 14KVa Diesel and 1500rpm with two wire auto start. Never just buy a cheap online generator unless you’re a mechanic!
We highly recommend that you contact a local company that also services and repairs generators, this way if anything is to go wrong you have someone local who can help you with any issues.
Is it possible to size an Off-Grid system without a generator?
In a sense it is possible to over-spec the solar panels to produce so much extra that they cover the power in the shortest days but in reality there is so much redundant power in the summer months that it may not be cost effective to do so.
Here at Energy Monkey we specialise in off-grid systems and can spec a system to any size required with the variables we have talked about in this article.
Is living off the grid good for you?
You may not have a grid connection and connecting to the grid means you will have to pay for the cables to be laid. This can often be very expensive.
To work out if an off-grid solution is best for you, you need to consider all of the options.
Once you have a grid connection you will have to pay for the electricity that you use and this is also a variable that you have no control over. Electricity production becomes more expensive as fossil fuels become more remote or harder to extract and is ever increasing. Also not many people know that 50% of all electric transported along the network is lost due to heat and voltage losses along the way – making this option effective but not that efficient.
Are you currently running a generator 24hrs a day for your power requirements or considering using a generator instead of connecting to the grid to reduce infrastructure costs and initial outlay of the connection. The cost of fueling a generator can also be a huge constant cost – that over the life of the system is high as well as not being very green burning fossil fuel.
The Off-grid option allows you to to start small and adapt and expand the system as you go, A generator or even unstable grid can become the back up to you power supply. The initial outlay can be relatively low cost with lower monthly costs for fuel or electricity as with the other two.
Last but not least the Off grid option is the greenest option converting renewable energy from sunlight on a daily basis and reducing the need to burn fossil fuels.
Why do people go off-grid?
Most of the people that are looking to go off-grid do so because they want to break away from ever increasing bills of public utilities and have more energy independence. Whilst others are looking to renewable energy for environmental reasons.
Some people choose an off-grid system because connecting remote houses or businesses to a grid is not possible, too hard or not cost effective.
Who lives off the grid?
Many different types of people choose to live off-grid. We have worked with many people, some who have very small power requirements to large buildings that have high power requirements and even huge 180KVa off-grid businesses. Off-grid is perfect for anybody that wants to create their own electricity, saving money on bills and being kind to the planet at the same time.
Can you totally be off the grid?
Yes it is easily achievable to be ‘totally off-the-grid’ no matter what your requirements are. If you want to use the tools in this article you can easily work out before you decide which way to go giving you a better understanding of your renewable energy requirements to meet the needs of your off-grid lifestyle.
Can you live off-grid in the UK?
Building an off-grid home in the UK is perfectly ok, we don’t have the best weather and this is just a factor that you think about when sizing your system.
Off-grid living for beginners? Need Help!
If you are looking to build an off-grid system but want support and guidance to make sure what you are doing is the most cost effective use of your money, then contact us, Energy Monkey is more than happy to help. We offer a free design service for our customers who buy from us.
How do I get the best prices on the parts for my off-grid system?
At Energy Monkey we will first talk through your requirements and then begin to design a system, which will end up as a kit list of parts. If you are buying the whole system from us we offer a discount that should make the package more cost effective. When buying from Energy Monkey you also get the added extra that you have a technical expert on hand to discuss each element of the system should you need this.
Technical support for your Victron off-grid system and after sales service!
As a Customer of Energy Monkey if you are building your own off-grid system or even if you’re an installer installing one for a customer we offer you a high level of technical support that you won’t find anywhere else. We understand systems and are able to support you every step of the way through the process even with helping you remotely program the system. If your system is connected to the internet we are also able to remotely connect to it should you need us to and help you diagnose an issue.
Ready to take the plunge into Off-Grid Living? Call us now for our expert guidance!