Six Steps To Solar Success!

In step one you will have calculated how much electricity in you will need to generate for your own daily needs in watt hours.

Divide your total daily energy consumption by the average peak sunlight hours to determine the required solar panel capacity. 

• Daily Energy Consumption (Watt Hours) = Wattage (W) × Hours Per Day

• Calculate the Number of Panels:
•  Required Solar Panel Capacity (W) = Total Daily Energy Consumption(Wh)​ Divided By Peak Sunlight Hours
  • Panel Specs: Find the wattage and voltage of the solar panels you intend to use.
  • Total Power: Divide the required panel output by the wattage of a single panel to determine the number of panels you will need.

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Number of Panels = Wattage of One Panel (W) Required Divided By Panel Output (W)

1. Energy Needs: In step one you calculated how many watt hours you require.
   Device 1 Consumes 100 watts & Is Used for 4 hours/day = 400Wh
2. Device 2: Consumes 200 Watts & Is Used for 2 hours/day = 400Wh

                                                                                                              Total = 800Wh/day

Sunlight Hours:
Using the number of direct sunlight hours you find for your location, we add this into our equations. In this example we are using (5) Five as the number of sun hours

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Required Panel Output (W) = 800 Divided By (Five Sunlight Hours ) = 160W

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Account for Temperature Changes (Cold Weather Coefficient):

• Solar panels generally have a temperature coefficient that affects their performance based on the temperature. Assume a typical value for the temperature coefficient is 0.5% per degree Celsius. For colder weather, panels may perform better, but for simplicity, we'll use a 10% overall system efficiency loss to cover various inefficiencies.
• Include Cable and Other System Losses:
  
• Consider another 15% loss due to cable resistance, inverter efficiency, dust on panels, etc.

• Combined Efficiency Loss:
• Combine the temperature and system losses into a single efficiency factor. An overall efficiency factor of 25% (10% + 15%) loss is typical:
• Efficiency Factor = 1+ 0.25 = 1.25%

Multiply the base solar panel capacity by the efficiency factor to get the adjusted capacity. 

Adjusted Solar Panel Capacity (W) = 160 W × 1.25 = 200W 

• Choose Solar Panel Wattage:
• Decide on the wattage of the solar panels you want to use. Let's assume you choose 100W panels.
• Calculate the Number of Panels:
• Divide the adjusted solar panel capacity by the wattage of one panel. 
• Number of Panels = 200W Divided By 100W Shows We Need 2 100W Panels

Always factor in local temperatures as your solar voltages will increase in cold spells.

Visit This Page For More Information On Sizing Solar Panels

Find Solar Panels & Complete Solar Systems here

These devices take power from your batteries (D/C) Direct Current and converts that power into alternating current (A/C) that your appliances will need. 

Look for "Pure Sine Wave" inverters, these are matched to your main grid electricity frequency 50hz for the UK and are more suitable than "Modified Sine Wave" versions. 

Look for the AC output maximum amperage if you are looking to power high power equipment.

For example a large fridge freezer may need 20 amps to start the compressor but some inverters can't supply enough surge capacity. 

Always buy the largest wattage Inverter you can afford that way it will meet your future energy requirements as your system grows.

All inverters have an efficiency rating due to energy used during the inversion process.

A good inverter may have a 90% efficiency rating or higher, while less expensive models may give 80% or less efficiency.

As an example lets use a 12V 1000W inverter drawing 230V 

The formula is (1000W / 12V = 83.33 Amps) but if we factor in the inverter efficiency rate of 90% the formula is now (1000W / 12V /0.9 = 92.59 Amps)

This means the true current draw on our battery is higher than the inverter output power would suggest.

I suggest that if you require an inverter rated over 2000 Watts, go with a 24V Inverter for the simple fact it's cheaper for wires & fuses.

A 12V inverter of 2000W or higher is suitable where the battery will be closer to the Inverter as cable runs are shorter, albeit a heavier gauge.

One of the first inverters i ever bought was the Edecoa 12v 3500W

I still use it to this day & it has never let me down, but is limited to 16 amps on the AC output.

The choice between 12V and 24V systems hinges on the wattage required. 

Systems operating at 12V often necessitate costlier, higher gauge cables, such as 70mm2, and larger fuses. Conversely, 24V systems can utilize less expensive cables and smaller fuses.

The higher the Inverter Voltage, the less expensive things become as the amps being drawn will be lower.

There are a few different types of inverters.

Grid tied inverters are used to feed excess electricity back into the main grid for which you will receive some form of credits. However, be aware that many Grid-Tied Inverters actually need the grid power to operate. In a power cut they wont operate!

You can also buy a grid tied inverter with energy storage.

These inverters can store excess energy into a battery for later use. 

These type's of inverter generally requires qualified installers & usually DNO approvals.

All in one Hybrid Inverters are becoming more popular and often an inexpensive solution to off grid electricity needs.

These inverters contain everything you could possibly need. 

They can take your solar panel energy, charge the batteries and even supply your appliances with grid power when your batteries run low - they even charge your batteries using grid power where required.

IMPORTANT : If you plan on using your existing electricity supplier's consumer unit with an inverter that exceeds 16A Per Phase (Grid Tied) you must always consult a professional installer / electrician who must notify your local DNO using the relevant G59 /G98 /G99 / G100 and have the permissions in place. 

You can visit the Government information website on the steps you can take to register an energy generation device HERE

There has since been a relaxation to the standard design rules of G59

It has been developed to allow those wishing to combine a G98 generator with an energy storage device. (Batteries)

To qualify,  the following conditions must be met:

• Total generation capacity installed should not exceed 7.36KW (including battery storage)
• All generators should be connected via a Type approved G83 protection device
• The maximum export should be limited to 3.68KW per phase utilising a Type approved G100 device
• The system should not generate during a power-cut (island mode)

Not sure who your (DNO) "Distribution Network Operator" is? 

Click Here To Find Your Power Company

For Guides On What You Can & Cannot Do Or For Guidance / Application Forms use These Links

In England Check Out This Website

In Scotland Check Out This Website

You will need an MCS certified installer / Electrician to apply and fit any On Grid system.

However, an MCS certificate is not a mandatory or legal requirement for system installation.

To locate an MCS certified Installer, visit THIS WEBSITE

Be safe! Don't Do Any Mains Electrical Works By Yourself. 

Many inverters can also be used to connect outlets to a separate consumer board, example would be wanting power in a garage or shed. Again always consult an electrician.

But lets assume you just want to power a couple of items, then choosing the right inverter is easier. 

You have a solar panel, a solar charge controller and you have a battery or two then its simply a case of connecting everything including the batteries to your inverter.  

Many inverters will come with cables that allow you to do this, but i would suggest you use better cables as they are often aluminium cored cables.

Always go for pure copper wires, you will have less problems and be sure to use the correct rated fuses between the battery and inverter!

Find Inverters Here

Lets assume you have an appliance that is rated at 120 watts & you want to power it for five hours a day.

You would take the Watts (120) & multiply that number by the hours of use  - 

(5 x 120) W x H = 600Wh.

So we will need at least six hundred watt hours of battery time per day.

You would also want to have some additional standby power to allow for those days that are cloudy or when no solar is being generated. 

A three day window is a good starting point, which means you can safely use your appliance during over cast days. 

We now take our 600Wh figure and multiply it by three. We now know we require a battery that is capable of producing 1,800 watt hours daily.  

A typical 12v 100 amp hour battery is rated to deliver (12V x 100) = 1200 watt hours. 

However flooded lead acid batteries can only provide 50% of their capacity! 

So a 100 amp hour lead acid battery can only supply a maximum of 600 watt hours. 

This is where LifePO4 batteries come into their own. 

A lithium battery can provide 100% of their stated capacity, so a 100 Amp Hour LifePO4 battery will supply a full 1,200 watt hours.

In order to supply our 1800 watt hour power needs, we would need either 1 X 24V 100Ah battery , 2 x 12V 100Ah lifePO4 batteries or 4 x 12v 100Ah lead acid batteries

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This gives us a total of 2400Wh of usable battery capacity. 2 x 1200Wh = 2400Wh

If you are planning on using a 24V battery, either a single 24V or 2 X 12V in series be sure to choose a 24 Volt Inverter of sufficient wattage to meet your needs.

Server Rack Batteries are becoming the new go-to option for residential off grid power demands. They are easily expandable and a very cost effective power system

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If you can afford the initial cost of buying a LifePO4 battery system I suggest you buy them over lead acid batteries.

LifePO4 batteries will out perform & out live lead acid batteries. 

Lead acid may seem a less expensive option, but you need to think in terms of years. 

You will need to replace lead acid batteries frequently as they will degrade much quicker than Lifepo4.

Find LifePO4 Batteries I Have Tested Here

Deciding on what battery to choose is not very difficult, it comes down to what you can afford and the size of system & voltage you want to use.

You can build your own battery bank using raw LifePO4 battery Cells, or use lead acid or a ready built LifePO4 battery. 

LifePO4 is very popular as they are much lighter than traditional lead acid, they don't need venting and can be stored in any position. 

Lead acid has many draw backs in comparison to LifePO4 but its all down to budgets and situations.

LifePO4 batteries have their own inbuilt battery management systems (BMS) to help keep everything balanced and have a fantastic life span (10 + years). 

Their ability to provide constant current sets them apart from all other batteries available today.  

Indeed LifePO4 batteries are far superior for solar use than any other battery type.

However, its your budget that matters!

LifePO4 do cost more initially but will actually save you money in the longer term. 

Some savings may be made by building your own battery!

AGM (Absorbent Glass Matt) batteries do perform better than traditional flooded lead acid batteries as do GEL batteries which use silica to make a gel formed electrolyte instead of liquid.

For larger systems it is more viable to go with Server Rack Batteries. 

These are usually in the 48V power region and are designed to work & communicate with certain off-grid & hybrid Inverter protocols.

Batteries are sized in Volts & Amp Hours. 

A 12 volt 100 amp hour battery is designed to deliver 1 amp of power over 100 hours, but there's a catch with lead acid batteries. 

Because you cannot drain a lead acid battery below 50% of its capacity (Damage Occurs) you need to divide any lead acid battery capacity in two. (100/2=50). 

So you can only expect 50 Amp hours, but there's another catch!  

Thanks to something called Peukerts law the batteries available capacity decreases as it is being drained. 

They are also very heavy!

All batteries have something called a "C" rating, this is an important piece of information that you need to be aware of, especially so if you are using lead acid batteries. 

Always look for batteries with a high C rate.  

A battery C rating is a crucial parameter that helps determine how quickly a battery can be charged or discharged relative to its capacity.

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It indicates the discharge rate relative to the battery’s maximum capacity.

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For instance, a battery with a 1C rating can provide a current equal to its capacity for one hour.​

• Imagine you have a fully charged 10Ah (ampere-hour) battery.
• At the 1C rate, this battery can deliver 10 amps of current for one hour.

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The higher the battery "C" rating, better the battery is overall. 

One battery i tested had a 130Ah rating but only if used at 0.001C which is not only misleading, its unrealistic.

Lithium ion / iron batteries work differently in that you can actually get 100% of the batteries stated capacity.

They will deliver a constant current at a constant rate of discharge. They can be placed in any configuration you desire & they weigh half that of lead acid.

Always buy the best battery you can afford and preferably go with lithium iron phosphate (LifePO4) batteries. 

They out perform and vastly outlive lead acid batteries.  

It is preferable to buy a LifePO4 battery with low temperature disconnect option, you will damage any lithium battery if you try and charge at zero degrees or below.

Low temperature charge disconnect will stop the battery from being charged in such circumstances. 

Higher quality batteries including the Fogstar Drift and some better solar charge controller brands offer this feature as standard and some batteries even boast a self heat function.  

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Watt Hours of any battery is calculated by multiplying the voltage by the Amp Hour rating. 

So a 12v 100Ah battery will have a watt hour rating of (12 X 100 = 1200 ) Watt Hours, whereas a 24V 100Ah battery will give 2400 Watt Hours. 

Similar lead acid battery would only produce (12 X 100  = 1200Wh / 2 = 600Wh)

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Many people get confused about connecting batteries together in terms called series and parallel.  

Have you ever put two or more batteries into a torch?  

If so you have already made a series connection!

Series connections increase voltage, but amp hours remain the same. 

So if you connect two 12v 50 Amp hour batteries in series then the voltage increases to 24 volts but the amp hours stay the same at 50 Ah.

Parallel connections are opposite, they keep the voltage the same but the amp hour rating increases.  

Using the above example 2 x 12v 50Ah batteries become 12v 100Ah batteries. 

These connections also apply to solar panel configurations!

If you have calculated how many watts you need each day, its time to size your battery bank, solar panel needs & find a suitable solar charge controller.

You will find batteries i have tested Here

Let's break down how electricity works and the differences between direct current (DC) and alternating current (AC) in simple terms to help you decide on a solar system voltage.

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Electricity is the flow of tiny particles called electrons through a material (Wires). This flow of electrons is what we use to power our homes, devices, and appliances.

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In direct current (DC) which we get from batteries, electrons move in one direction, like water flowing through a hose. This type of current is produced by sources like batteries and solar panels. DC is commonly used in electronic devices because it provides a steady and constant voltage.

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In alternating current (AC) the power you get from your home sockets for example, electrons switch directions back and forth, many times per second. This back-and-forth motion is like the tide coming in and out. AC is used in homes and businesses because it's more efficient for transporting electricity over long distances. The power that comes from your wall sockets is AC.

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1. Volts (V): This measures the electrical "pressure" or force that pushes electrons through a circuit. Think of it like water pressure in a hose.
2. Amperes (Amps, A): This measures the flow of electrons, or current, through a circuit, similar to the volume of water flowing through a hose.
3. Watts (W): This measures the rate of energy transfer. It tells you how much power is being used or produced. It's like the power of the water spraying from the hose.
4. Watt-hours (Wh): This measures the total amount of energy used over time. If a 100-watt light bulb runs for 1 hour, it uses 100 watt-hours of energy.

Understanding Watt-Hours 

• Watt (W): A unit of power that indicates the rate at which energy is used or produced. For example, a 60W light bulb uses 60 watts of power.
• Hour (h): A unit of time.

The energy consumed in watt-hours can be calculated using the formula: 

Energy (Wh) = Power (W) × Time (h) 

1. Light Bulb Example:
   A 60-watt light bulb running for 2 hours: Energy = 60W × 2h = 120Wh 
2. Laptop Example:
   A 50-watt laptop running for 5 hours: Energy = 50W × 5h = 250Wh 

Watt-hours are commonly used to:

• Measure Energy Consumption: Electric bills are often calculated based on kilowatt-hours (kWh), where 1 kWh = 1000 Wh.
• Size Batteries and Solar Systems: When designing off-grid systems, knowing the energy consumption in watt-hours helps determine the size of batteries and solar panels needed.

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Many devices and systems, like solar panels, produce DC power. However, since our homes use AC power, we need a way to convert DC into AC. This is done with a device called an inverter. An inverter takes the steady DC voltage and changes it into an alternating voltage that can be used by AC appliances. It essentially "chops up" the DC and rearranges it into an AC waveform.

Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage, current, and resistance in an electrical circuit.

It is typically expressed by the equation:

 V = I × R 

where:

• V is the voltage (measured in volts, V),
• I is the current (measured in amperes, A),
• R is the resistance (measured in ohms, Ω).

Voltage (V):

• The electrical potential difference between two points in a circuit.
• It is the "pressure" that pushes electric charges through the circuit.

Current (I):

• The flow of electric charge through a conductor.
• It is the rate at which charge is flowing, analogous to the flow of water in a pipe.

Resistance (R):

• A measure of how much a material opposes the flow of electric current.
• Higher resistance means less current flows for a given voltage.

Why Higher Amps are Needed in Lower Voltage Systems​​

In electrical systems, power (measured in watts) is the product of voltage (V) and current (I), given by the formula:

Power (P) =Voltage (V) × Current (I)

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When the voltage is lower, the current (amps) needs to be higher to deliver the same amount of power. For example, a 100-watt device would require:

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• 10 amps at 10 volts (since 100=10×10100 = 10 \times 10100=10×10)

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• 1 amp at 100 volts (since 100=100×1100 = 100 \times 1100=100×1)

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When current flows through a conductor (Wire), it encounters resistance, which causes some of the electrical energy to be converted into heat. This is described by Joule's Law: Heat (P)=I2×R\text{Heat (P)} = I^2 \times RHeat (P)=I2×R

Where:

• I is the current (amps)
• R is the resistance (ohms)

The heat generated is proportional to the square of the current. This means that as current increases, the amount of heat generated increases exponentially. This is why high-current systems need thicker conductors and efficient cooling to manage the heat produced.

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Earthing, or grounding, is essential for electrical safety. It provides a path for electricity to flow safely into the ground if there's a fault. This helps prevent electric shocks and fires. There are different earthing systems used in the UK:

TNCS (Terra Neutral Combined and Separate):

• In this system, the neutral and earth conductors are combined into a single conductor in part of the installation (usually from the transformer to the house). Inside the house, they are separated.
• It’s the most common system in the UK because it’s efficient and cost-effective.

TT (Terra-Terra):

• In a TT system, the house has its own earth rod driven into the ground. The earth connection at the house is independent of the supply network's earthing.
  • This system is often used in rural areas where it's difficult to connect to a TNCS system.

These are other methods used, be sure to check out what is permitted or used in your area