Off-Grid Solar in 10 Minutes: A Beginner’s Guide

Think of the four main components of an off-grid solar system like collecting and using water.

Here are the basics:

The solar panels are like the rain falling on your roof

Solar panels are where your electricity comes from. The more sunlight hitting the panels, the more electricity they can generate.

They run the house during the day (unless there’s no light) and any excess gets stored in the battery bank (if you have more than one battery, it’s called a bank).

The batteries are like your water tank

During the day, batteries store electricity generated by the solar panels so you can use it later or when there isn’t enough sunlight during the day.

The inverter is like the pump supplying water from the tank to your house

The inverter takes the electricity available from your solar system and supplies the type of electricity your normal household appliances need.

Water pumps come in different sizes depending on how much water you want it to supply at any one time. Inverters are like that too. The more stuff you want to run at the same time, the bigger your inverter needs to be (and the more costly).

The generator is your backup water supply

Just like you’d need a backup water supply during a drought, if there hasn’t been enough sunlight during the day to fill up the batteries, a generator can provide another source of electricity and recharge them (as well as power the house at the same time).

In short: Panels = Generate. Batteries = Store. Inverter = Deliver. Generator = Backup

Aasking about the cost of off-grid solar is a bit like asking how much a house costs. It depends on what you need, want or can afford.

A small system in NZ for a tiny house or cabin with low power use in winter, using cheaper components (or even DIY), might start at $4,000 excluding a generator or installation.

They are perfect for what they are. Your expectations need to be realistic when it comes to reliability, longevity, technology and ongoing support.

Costs for Quality Off-Grid Solar Systems

A quality tiny house system with lower loads, designed for maximum longevity and using proven technology with solid ongoing support, could start at $15,000 excluding a generator and installation.

For an ‘average’ home, a quality expandable system might start at around $24,000 to $34,000, excluding a generator and installation.

Homes with very large daily loads can’t (and shouldn’t) be designed using lower-quality or DIY components. Pricing could start at $35,000 to $70,000, excluding a generator and installation.

The point is, pricing is extremely variable and there’s no such thing as one supplier serving every type of customer.

Focus on Value for Money

In our experience, value for money is just as important as price, because value means different things to different people.

For example, one person might see better value in paying $23,000 for a quality system from a specialist off-grid supplier, with batteries expected to last 20 years or more.

Someone else might prefer to pay $16,000 for a system with similar capacity (the same number of panels and equivalent battery storage) even if the expected battery life is only 10 years.

It depends on what value for money means to you.

Summer is easy for off-grid solar. The days are longer, the sun is higher in the sky and there’s usually plenty of solar energy available.

Winter is what matters. The days are shorter because of our latitude (where our country sits on the globe). The sun is lower and periods of cloud and rain mean your solar panels generate much less electricity.

To give you an idea of the difference, NIWA research found that solar energy in the Wellington region is typically three to four times higher in summer than winter.

In mid-winter, on 22 June the sun is at its lowest in the sky at ‘solar noon’ at about 25 degrees above the horizon. In summer on the longest day, on 22 December, it’s significantly higher in the sky at 72 degrees. Source: TimeAndDate.com.

That’s why we design your system around winter, not annual averages or how well it performs in summer.

Where you live matters too. Winter solar conditions vary considerably around New Zealand. Taranaki and Nelson, for example, have historically much higher average sunshine hours than the West Coast or Southland.

A good off-grid design takes these factors into account.

You might read that an off-grid system should have enough batteries to run your house for three to five days without any solar.

In reality, we usually design for around one to two days of battery backup (sometimes called autonomy).

Why not just add more batteries or panels? Yep, you can do that but the price shoots up, because in winter there’s little point having a bigger battery bank without enough solar generation to fill it.

For example, you might spend another $15,000 on solar panels and batteries so your generator almost never needs to start.

Or, you could just spend $5,000 on a backup generator that runs occasionally during the worst periods of winter.

At some point, you reach diminishing returns. Spending thousands more on extra panels and batteries just to avoid occasionally running the generator may not make financial sense.

It’s your choice completely, and one of the things we’ll discuss.

For more detailed information, read our Off-Grid-Solar Batteries section.

Probably, but not always.

Think of your generator as insurance for those bleak winter days when there simply hasn’t been enough sunlight to keep your batteries charged.

In a properly designed system (not too big or too small), the generator shouldn’t be running all the time, or every day in winter.

It might only start occasionally during winter, topping up your batteries while also supplying power to the house during more than one day of bad weather.

As we explained above, you can add more solar panels and batteries if you really don’t want a generator, but at some point that becomes an expensive way of avoiding something that might only run occasionally.

There’s more to generators than we need to cover in this 10-minute read, including what size you need, auto-start and how they work with your solar system.

If you want to dig deeper, read our guide: Do You Really Need an Off-Grid Solar Generator?

You might read that living off-grid means you have to cook with gas, use solid fuel like a wood burner and avoid electric hot water.

It doesn’t.

A properly sized off-grid system can run an induction hob, electric oven, heat pumps and a hot water heat pump for hot water. Just like a grid-connected home.

Of course, these can be some of the biggest users of electricity in your house. The more appliances and equipment you want to run on electricity, the larger your system will need to be (and therefore more expensive).

You can read our article about induction cooking for more insights.

To keep the system size and price down, many customers choose gas or wood or a wetback to reduce their daily power use in winter.

But that’s a choice.

Our job is to give you the options. Apart from the budget to consider, there are pros and cons.

We start with deciding how you want to live first. Then we design the system around it. If that doesn’t suit you or the budget, we can start looking at alternatives to reduce the size and cost of your off-grid solar system.

Is off-grid solar actually worth it? It depends on what you’re comparing it with.

Most people looking at building a new house are interested in the all-up cost to go off-grid compared to getting the power connected.

If mains power is already available at your property for a reasonable price, going off-grid is unlikely to make financial sense compared to building somewhere where the cost to get connected is $100,000.

If you’re looking at bare land, get a price for connecting to the grid or talk to us before you decide whether off-grid solar is worth it.

It’s not always about money either. Where you want to live, whether mains power is even practical and why you want to live off-grid all matter.

This is a big topic that can’t be covered in depth in this 10-minute read. We cover this subject in a lot more detail in our article “Is Off-Grid Solar Worth it?” Check it out.

When power is cut to a grid-connected home, you can call the power company or just wait until someone sorts it out.

Off-grid solar is your power supply.

And while problems with quality off-grid systems are uncommon, they still happen.

That’s why support matters. If something goes wrong, can someone diagnose it remotely? Are parts available in New Zealand? And who is going to fix it?

Other things to check include whether the supplier has in-house technicians or engineers to handle technical issues, and how warranty claims are handled.

An established and credible supplier will be happy to show you evidence of these things to give you the assurance you need.

You don’t need to worry about all of that now.

Just remember when you’re eventually comparing systems, you’re not only buying the equipment. You’re also relying on whoever is going to support it.

Here are a few tips and tricks in the “I wish someone had told me that earlier” bucket.

The ideas below are not theory or a ChatGPT list. They’re based on years of real experience and hundreds of system designs:

1. Don’t design your system around your budget. Design it around what you actually need

If the price for a quality off-grid system is more than your budget, that’s when you look at the options. Maybe use gas for cooking, install a wood burner, reduce some loads, or make other compromises to bring the system cost down. Maybe start smaller and add batteries and panels later, as long as the system has been designed to allow for that expansion.

2. Do start planning early if you’re building

Don’t design the whole house and leave the solar until the end. Planning your solar system too late can be costly, especially if you’ve unintentionally chosen a high-draw septic system.

This is just one example. Some of the decisions you make about your house will affect how much power you need.

3. Do design for tomorrow, not just today

Think about what might change at your propery and in your life in the next 10 to 20 years, particularly if you intend your home to be long term.

Ading an EV, workshop, spa pool, granny flat or other large load needs to be considered at the start, where possible because it could affect how we approach your design.

4. Do think about where the solar panels will go

A beautiful sunny spot in summer might be shaded by trees or hills when the sun is lower in winter.

Some roof types are tricky or expensive to attach panels to, or there may not be enough roof space to generate enough electricity to live how you want to live.

5. Don’t assume you need to give up normal appliances.

You can run a whole village off-grid, so you don’t need to give up anything if you don’t want to!

The question isn’t ‘Can I run normal appliances?’ The question is ‘How will running all-electric appliances affect my system size and therefore price?’

Remember more electrical appliances require more panels (more generation), so roof space or ground-based array space should be considered.

6. Do ask whether the system can be expanded later

Adding more batteries and solar panels is possible with most quality off-grid solar systems, but can be limited by the size of your inverter or inverters.

If your power use is definitely increasing in the future, early planning is a must.

For a deeper dive, take a look at our in-depth article called: Can My Off-Grid System Be Expanded.

7. If you’re buying bare land for an off-grid house, don’t forget these things.

Consider water pumps, electric opening gates, electric fencing, wastewater and septic systems, driveway or outside lighting, internet (satellite internet is power hungry) and CCTV.

8. Don’t rely on AI to design your system

AI can be useful, but it is based on collective knowledge, while every situation is different.

There is no substitute for an experienced designer who can customise your solution.

Because of experience, they know what to do, and importantly, what not to do.

9. Do call us.

If you’ve made it this far, you probably didn’t read this for fun or entertainment.

So, if you’re ready to talk about your project and what you want to achieve, get in touch with us.

You don’t need to know what size system you need, how many panels or batteries you need, or to have everything figured out.

That’s our job.

If you’re not ready to talk yet and want to do some more research first, that’s fine too.

We’ve put together a growing Off-Grid Solar Library covering many of the subjects we’ve touched on in this guide in much more detail.

You can also visit our Blog, where you’ll find articles, case studies and practical advice based on the things we encounter designing and supplying off-grid systems around New Zealand.

Or just give us a call.

We like helping people with their questions.