Off-grid solar systems are very different compared to their grid-tied counterparts, presenting unique challenges that demand careful consideration.
While grid-tied systems can almost always fall back on the grid if the solar or batteries malfunction, off-grid systems stand alone, calling for thorough deliberation before you take the leap.
With the help of an expert in the field, we’ll guide you through the key considerations that will help you make an informed decision about buying an off-grid solar system.
12 Tips for Off-Grid Solar Systems
Glen Morris needs no introduction to many in the solar industry. He is one of the leading authorities in off-grid solar energy systems in Australia right now.
Presently, Glen is General Manager at Smart Energy Labs, an off-grid living laboratory at Mount Toolebewong in the Yarra Valley, set up to do product testing and training courses for solar, batteries, and everything off-grid.
We asked him to put together his top 12 tips to consider when buying off-grid solar. Bear in mind, if you’re serious about going off-grid, the following is merely scratching the surface.
Over to you Glen…
Tip #1. Keeping The Upfront Cost Manageable
An off-grid renewable energy system is like pre-purchasing your next ten years of electricity, hence there is a considerable up-front cost. That cost is directly proportional to how much energy you require the system to supply. Keeping the demand as low as possible is key. By choosing appliances with high energy efficiency ratings, you can reduce your overall energy demand, and avoid a larger, more expensive system.
Tip #2. Passive Solar Design Is The First Step
Consider the passive solar design of your dwelling as the first step in saving money. The passive solar design maximizes natural heating and cooling opportunities through smart placement of windows, insulation, and thermal mass. By harnessing the sun’s power effectively, you can minimize your reliance on active heating and cooling systems, reducing your energy consumption and increasing the efficiency of your off-grid system.
Passive solar design basic principles. Image: yourhome.gov.au
Tip #3. Choose An Experienced Off-Grid Solar System Installer
When it comes to off-grid installations, selecting the right installer is paramount. It’s always best to choose an experienced off-grid installer. Assess their expertise by asking them to see examples of their previous work. Even better, try to speak firsthand to their previous customers, as well as the usual avenues of Google searches and review websites.
Tip #4. Supply Detailed Appliance Information And Load Profile
To ensure your off-grid system is designed accurately, provide your system designer with an anticipated load profile — a comprehensive list of appliances, their power ratings, and their usage patterns over a 24-hour period. This load profile is crucial for sizing your system appropriately and optimizing its performance based on your specific energy needs throughout the day. Be honest and conservative in your estimate.
A simple daily load profile like this one is easy to make with an Excel spreadsheet.
Tip #5. Get Design Sign Off From The Installer/Designer
Before finalizing your off-grid system design, obtain a sign-off from your designer on the daily energy supply estimate for the worst month of the year, and a load profile showcasing appliance power ratings and usage patterns over 24 hours. This estimate gives you a clear understanding of your system’s performance in conditions it has been designed to operate under.
Tip #6. You’ll Need A Backup Generator (Yes, Fossil Fuel!)
Consider investing in a reliable auto-start backup generator for electricity during extended low solar input or unexpected events. This backup option ensures that you have a backup plan and can continue enjoying an uninterrupted power supply when needed. It can even form part of the system design for low solar months.
Tip #7. Don’t Use A Hybrid Inverter
While hybrid inverters are popular for grid-tied or grid-connected setups, they may not be the most suitable choice for off-grid applications. The primary reason lies in their low surge ratings, which means they may not be able to handle sudden spikes in power demand that can occur in off-grid scenarios. Additionally, hybrid inverters may lack the auto generator start function.
Left: Sungrow SH5 hybrid inverter, and right: Seltronic SP PRO off-grid inverter. Both will function off-grid, but the dedicated off-grid inverter is better suited. Image: Sungrow and Seltronic
Tip #8. Oversize the PV Array To Optimize Battery Size
Oversizing the solar array can be a smart strategy if your energy demands are largely daytime usage. You can reduce the required battery size by generating surplus electricity during peak sunlight hours. This approach helps optimize your system’s performance and can save costs.
Tip #9. Choose A Battery Suited To Your Local Climate
Lithium-ion batteries have largely replaced lead-acid for off-grid due to falling prices and much greater usable capacity. However, it’s important to consider the restricted charge rates of lithium-ion batteries in temperatures below 5ºC. Ensure that the battery technology you choose aligns with your climate as well as your energy requirements.
Tip #10. Comply With Battery Standards And Regulations
You must comply with battery standard AS/NZS 5139, which outlines restrictions on battery installation locations in habitable rooms. Typically, a separate building or garage is a suitable location for battery installation to ensure that you meet safety and regulatory requirements.
An off-grid system in a purpose-built shed – lithium-ion batteries, inverter/charger, solar inverters. Image: Off-Grid Energy Australia
Tip #11. Be Prepared To Adapt And Live By The Weather
When living off-grid, weather conditions influence your energy consumption significantly. Focus on energy efficiency to maximize your available power during low solar input. Embrace seasonal appliance selection, like using electric cooking in summer and wood or gas options in winter, to align with solar energy availability. This smart approach optimizes your energy usage and allows you to fully utilize your off-grid system throughout the year.
Tip #12. Seasonal Energy Use and Surplus Generation
For temperate climates, often the lowest dip in solar production occurs mid-winter, which aligns with higher energy use (longer nights and indoor activities) thus off-grid PV-designed systems will have significant surplus energy in summer months. This allows for seasonal changes in energy use. This surplus energy can be used for various purposes, such as water heating, pumping water for seasonal storage tanks or dams, or even cryptocurrency mining!
Will crypto mining with summer excess solar pay off your system? Image: Bitcoin Magazine
Is Off-Grid Solar Really For You?
So, after hearing some insights and expert advice from solar off-grid guru Glen Morris, it’s clear that thoughtful planning is crucial. The off-grid solar system is a completely different beast than a grid-tied system. We’ve only just scratched the surface, so it may be the start of a long journey if you choose to take it.
One more thing that may be a stumbling block before you even get started – Glen says as a ready reckoner, be prepared to fork out a system build price of $2,000 to $4,000 per kWh of daily energy demand!
If that’s in your budget and you’d like quotes from up to 3 highly-vetted local companies for a proper off-grid system, click here.
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