How to Size an Off-grid Solar Power System
Of all of the tasks required in designing an off-grid solar power system, one of the most challenging is specifying the correct size for your needs. You need to accurately assess how much energy you need for daily use and build in enough redundancy for future requirements while not overspending. It’s a balancing act that can seem a little overwhelming at first.
It doesn’t need to be though. Sunstore has an excellent off-grid solar calculator. UK conditions require a regionalised calculator and that’s what we provide. Our climate has unique characteristics and our calculator takes them all into account.
The Anatomy of an Off-grid Solar Power System
An off grid solar system is made up of two main parts:
- Solar panels
- Battery storage
On larger off-grid systems it is usual to add the following parts:
- Inverter/Inverter charger
4. Generator or backup power supply
Off-grid Solar System Power Calculation
In an ideal world the solar panels you select will be sufficient to generate enough power each day to exceed, or at least equal, the amount of power required. Different parts of the world and even different counties within the same country have different levels of sunlight each day.
In the UK, December is the worst month for sunlight having short days and often overcast weather. June is the best for generation as it has the longest days and higher average sunshine on average. The Met Office has a great climate breakdown that you may find useful.
Regional variations aside, the composition of your household also adds to the power requirement. How many children do you have? How many appliances do you use and how often do you use them per week? How often would you use multiple appliances at once? Do you have energy efficient appliances? Are you planning to add to your family? Add more appliances? Planning on buying energy efficient appliances in the future?
All these things need to be calculated to ensure you can generate enough energy for your needs.
You can use our off-grid solar power system calculator to help with some of that.
Off-grid Solar Power System Setup
In some instances there may be inadequate roof space to generate enough power all year round. Your roof may be oriented in the wrong direction or have features that prevent solar panel mounting. There may be the option to ground mount your solar panels if you have enough space garden that also orients in the right direction.
If you don’t have sufficient mounting space for an off-grid solar power system we would add additional or backup power sources to supplement the solar.
An off-grid solar system battery bank is designed to have storage for one day of power consumption. Many people suggest 3 days’ worth of storage which may work in some situations. However, it isn’t ideal for everyone and comes at a financial cost.
Off-grid Solar Power System Calculator
Our simple off grid solar system sizing calculator is a good start to help ascertain viability of your project.
Simply enter the average power you use per hour and number of hours used per day.
Our calculator will give you 2 options.
The summer figure shows the perfect system size for summer only use systems and larger homes and off grid supplies where a generator can be used to back up the power when needed.
The winter figure shows the solar and battery recommended for complete solar autonomy to guarantee power all year round.
If you would like help with your solar system design please contact one of our expert technicians. We would be happy to help!
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