By Rhys Coffin, Off-Grid Solar Designer
If you are building a new home or looking at a relocatable house and need to go off the grid for your power, this article could save you a lot of time, money and hassle.
Most of the information below is common sense and based on experience with over 900 successful off-grid solar installations around New Zealand.
We’ve created this list of seven areas or items that you can use as a checklist or a guideline.
If you need information or advice about your specific situation, please go ahead and Book A 15-Min Phone Call or get in touch. Our design service is free.
Let’s get started:
1. Does off-grid solar make financial sense?
While some people will choose to build a house to be off the grid as their first choice (even though a grid power connection is nearby), most people’s decision is based on the price of getting grid-connected versus off-grid solar.
The size (and estimated price) of your solution is the first step. You can get a general idea of the cost of a system by reading our Sizing & Pricing page.For an accurate estimate, get in touch for a short conversation.
Everyone’s different, but an ‘average’ quality system for a 3-bedroom house could cost $30,000 for the components, up to $8,000 for an approved generator and say $7,000 for installation.
At $45,000 all up, a $10,000 quote to get mains AC power connected would be a logical alternative, even with the ongoing cost of a power bill.
If the nearest grid connection is hundreds of metres away (or kilometres away) from your building platform, then you’ll have little choice but to go fully off-grid.
Where it can get tricky is for distances of 100m or less. In this situation, you need to consider:
- The cost of your local electricity lines company to run cable to your property. This may include the cost of a transformer, not just the cost of running AC cable underground or overhead on power poles. To start your research, use the Electricity Networks Aotearoa website to locate your lines company and talk to them.
- There will also be a cost to get an AC cable laid in a trench from the boundary to the building platform. This will usually be done by your local electrician, so you’ll need a quote to do this work.
- Your intended ownership/occupancy term of the property. If it’s your last home, the capital cost of a quality, expandable off-grid system could make sense, especially with the expected lifespan of some batteries of up to 22 years. However, if you intend to sell your home in the next few years, and the cost of connecting to the grid is low, getting grid-connected would be your preferred option.
There’s no firm price threshold, but if the cost of getting connected is less than $15,000, the case for off-grid solar might not be strong. This assumes your motivations are based primarily on spending the least amount of money.
If your motivations are based on independence or other reasons—and you are not as constrained by the budget—then an off-grid solar solution will make sense.
2. Don’t leave it too late
Talk to us early. Don’t rely on your real estate agent, architect, builder, plumber, electrician or guy down the road who’s been off the grid for 10 years, to give you meaningful advice.
The components and technology change fast. Most well-intentioned professionals and tradespeople usually won’t have enough experience, let alone the expertise, to provide sensible and nuanced advice.
Don’t call the week before your transportable home arrives, or the week before your move-in date. Start planning at least three to six months ahead.
In the best-case scenario, leaving it until the last minute could mean a rushed design and an undersized or oversized system. It might also mean corners are cut, which could increase the chances of mistakes being made.
In the worst-case scenario, your project may be delayed. At different times of the year, electricians/installers can have a backlog of work that may delay your installation.
3. Plan your system based on your needs, not just your budget
It’s tempting to underestimate your power needs to keep the price down, but that can cause real problems during winter, including overuse of the generator or overloading your system completely.
The objective of our design team is to give you sensible advice based on a range of factors, including:
- Your power use in winter over 24 hours (load evaluation)
- Your local sunshine hours
- Characteristics of your new build
- Your lifestyle factors
- Your new house characteristics
- Other factors
If the design we recommend exceeds your budget, we’ll give you options. These include substituting electric appliances or equipment with lower-draw or alternative options, or downsizing your power use until you can afford to add extra solar panels and batteries later.
New technology in battery chemistry and inverter technology allows you to start smaller and expand your system over time.
But this has its limits.
For example, if you have a budget for a tiny house but have expectations to run a full-time home with all electric appliances and equipment by simply adding more panels and batteries, you’ll be disappointed.
Adding extra panels and batteries CAN be a good option, but there are limitations with inverter sizing and other factors to consider.
You may be able to get a system within your budget by looking at alternatives (with the intention to add panels and batteries later), but you’ll need to get the best advice to make a plan to achieve this.
Please talk to us about your options.
4. Be aware of local consenting factors
Be mindful that there may be some factors that can delay, or even prevent your home from being built the way you want it to be built, or on your chosen spot.
Geotechnical reports can affect the location of your house on your land. This may impact available light and make your solar design tricky or impossible.
Your local council may require you to have a powered septic or wastewater system, which can significantly affect your daily load evaluation and increase the price of your system.
Be aware of the wind zone rating at the property. If it’s zoned as high or extreme, this may affect your design and increase the cost due to additional panel fittings and components.
5. Roof-mounted or ground-mounted array?
Talk to us at the early concept stages of your design to get advice on your options for the location of your panel array.
Your designer or architect may inadvertently allow for panel location on roof surfaces that are unsuitable or unusable. These could include:
- Roofs facing south
- Shading from trees, structures or hills
- A roof area that is too small for the panels you need. A 15-minute phone or video call with us should give you an indication of the number of panels required, based on your load evaluation.
- Lack of knowledge about how the solar ‘strings’ need to be configured. For example, for a tiny house or small house system, all panels need to be on the same plan, same orientation and same pitch.
Your roof type is also a factor to consider early on. Some roof types are tricky or not suitable for panels, including:
- Concrete panels
- Some pressed metal tile panels
- Membrane roofs
- Curved roofs
If a ground-based array is preferred, you can have a purpose-built engineered solution at a higher price (watch the start of this video to see one) or a lower-priced timber DIY array.
There are pros and cons to consider. Please talk to us.
6. Appliance and equipment selection
Alarge part of deciding on a correctly sized off-grid solar house is your daily load over 24 hours in winter.
The biggest impact on your loads is usually based on how you manage your:
- cooking
- heating
- heating hot water
The reality is that you can run whatever you want. It’s just a case of the money!
In our experience, most people are motivated to know all the different options available to minimise the overall size and price of their system.
For example, a family home with all electric appliances (no gas or solid fuel) may require a correctly sized off-grid solar system that starts at $50,000 up to $100,000+.
A very large house may require power for under-floor heating, swimming pool pumps, pool heaters, and other minor dwellings on the same property connected to the one system.
Although satellite internet (such as Starlink) is very convenient, it can have a high draw of up to 1,700W per day (1.7kWh).
In a grid-connected home, 1.7kWh to power satellite internet is not a concern compared to 25kWh per day for the ‘average’ grid-tied home. But for a tiny house with a 5kWh daily load, that’s significant.
For more Tiny House tips, check out our Tiny Home Off-Grid Solar Guide.
7. Futureproofing
Give some thought as to whether your power use will increase, decrease or remain stable over the next 10-20 years.
Your future plans can affect how we design your initial system and save money in the long term. If the budget is tight, you may have no option but to size your system for your needs now. And that’s OK.
But if you have flexibility with the budget, it makes sense to allow for expansion, especially if you want to plan for future eventualities.
Things to consider include:
- Children leaving home
- Family growth ( more children)
- Future increasing loads such as spa pool, EV charging, swimming pool, etc.
While no one can predict what might happen in 10 years, giving it some consideration should be part of sizing your system for your new build house.
Conclusion
Building an off-grid solar home is a big step, but with the right planning, it can be one of the most rewarding decisions you’ll ever make. The key is to think ahead—allow enough time to design a system that matches your lifestyle, location, and long-term needs.
By weighing up the true costs of grid connection versus off-grid investment, choosing the right appliances, and allowing for future growth, you’ll avoid common pitfalls and set yourself up for success. A quality system, designed properly from the start, will give you the comfort and security of reliable power without compromise.
Ultimately, living off the grid isn’t about sacrifice—it’s about independence. With today’s technology, you can enjoy modern living while cutting ties to monthly bills and outages. Get the right advice early, design with care, and your solar-powered home will provide peace of mind and freedom for decades to come.
Go ahead and read more articles in our Off-Grid Solar Blog, or return to home page to access the off-grid solar information you need.
