Thinking of going off the grid with solar energy? We’ve created this complete guide to help you!
Off grid living means you have no connection to the electric utility’s distribution network. When you go off-grid, you are the ‘power company’. A fully functional off grid solar system comes with a four essential components: Solar panels, Off grid batteries, Charge controller and an Inverter.
Calculate your yield
Before choosing your solar components, you will have to calculate and estimate your consumption. You can do this manually or you can use our solar calculator at: https://gridfree.store/Solar-Calculator.
If you want to do this manually, simply calculate watt hours by using your appliance power rating to multiply by the time (hours) of run.
e.g If you’re running a 10W light bulb for 5 hours a day, TV(80W) for 3 hours, Phone charging(10w) for 8 hrs, and a fan (125w) for 4 hours.
10W x 5 hr = 50Wh
80W x 3 hr = 240Wh
10W x 8 hr= 80W
125w x 4 hr = 500W
Total = 870Wh.
You will need to consider a 20% energy loss in the system, which brings your requirement up to: 870 * 1.2 = 1,044Wh
Now you can spec your components based on your energy consumption.
Solar Panels — converts sunlight into DC (Direct Current) energy.
In an off-grid situation, you must make sure your panels can supply enough electricity to meet you consumption in every month of the year. People tend to use more electricity during winter when Solar modules are not as effective (shorter days = less sun hours). Hence, it’s always smart to plan for the worst-case scenario and get the most effective solar panels. We offer two types of panels: The 310W PERC Mono-crystalline and the 315W PolyCrystalline. PERC Mono panels are costlier but are more efficient than the PolyCrystalline panels.
If we’d to assume an average of 4 effective sun hours a day. We can use this information to work out our panel output. (You can use organisations like NIWA to work out your exact sun-hour : https://www.niwa.co.nz/our-services/online-services/solarview)
310W x 4hr = 1240Wh
This suggest that output from one of our 310W Perc Mono panel would be enough to cover our consumption of 1,044Wh. It will also be able to fully charge a 12V battery in a day.
Battery — Stores energy so you can use it during the night
Batteries are an essential part of an off-grid solar system, it will provide constant source of stable and reliable power that allows to power devices when the sun is down. Deep-cycle lead acid batteries are by far the best type of batteries to use for in an off-grid solar system. They are designed for deep discharge and have a life-span of 5–12 years. You will want to avoid car batteries at all cost, as they’re designed for supplying short bursts of current and wouldn’t last long when deeply discharged.
You never want to completely drain your battery to 0%, it will permanently damage your battery and significantly reduce it’s life-span. We recommend a 50~60% depth of discharge, so work out your requirement and multiply it by 2.
Using our example:
1,044Wh/12V = 87 Ah, 87x2=174Ah.
You can round this up and use our 12v200ah Gel VRLA battery. Please note: most off-grid solar systems are ran on a 12 or 24V system, if you’re running one Solar panel you will need a 12V battery.
For more information, please see our blog post on ‘the best batteries for off grid Solar :
Charge controller — Protect battery and optimise output from panel
The charge controller is a piece of equipment that is placed between solar panels and batteries. It regulates and controls voltage to prevent batteries from been overcharged. A highly effective charge controller can have a significant impact on output and increase your solar yield.
We’ve always recommended our customers to use the MPPT charge controller. It is designed to accept input from solar panels at a high voltage, and charge the batteries at an appropriate low voltage. A smart optimisation algorithm is used in this process to maximise the amount of power going to the battery.
Calculate the size of charge inverter by dividing the size of your Solar panel by 12volt. (310W/12V= 25.8ah) you can round it up and use our 30a EPEVER Tracer 3210an MPPT model.
If you would like to reduce your cost and opt for the PWM controller, you can read our blog post on ‘MPPT vs PWM’ :
Inverter — Converts DC power to AC, so you can run your appliances
Most off grid solar systems will need an inverter. The inverter converts DC energy produced by solar panels and converts them into AC (Alternating current) power to run your household appliances. Having a good inverter means that all your equipments and appliances will run seamlessly.
You must choose a inverter that matches the battery voltage and have enough output to run the appliances needed — in our case, we will need a 12v 1000w inverter. We’ve always recommended our customers to use a pure sine wave inverter in all off-grid solar installations, you will have the best quality of AC output that wouldn’t damage your appliance or affect it’s use.
Please have a read of our blog ‘The best inverter for your off-grid solar kit’ to learn about running different appliances with continuous and surge power demand:
Wiring
Wiring all the components together can be difficult for a first-timer, so please reach out to our solar experts for a complete wiring diagram.
Safety
Safety is paramount when dealing with DC voltage. We recommend using DC/AC breakers between all connecting equipments to uphold the highest safety standard.
- Between solar panels and charge controller (25A)
- Between charge controller and battery (60A)
- Between battery and inverter (200A)
If your off-grid solar installation is in a home or cabin (non-RV), please also install a surge protector to minimise the potential impact of lightning events.
The GridFree.Store is dedicated to provide New Zealanders with quality off-grid solar equipment and we’re a big supporter of DIY installs. Speak with one of our solar expert today to get started on your off-grid Solar!
