Off Grid Solar for Dummies: 2021

 – By Rhys Coffin, Off Grid Solar Designer

No, you’re not really a dummy.

In fact, it’s fair to say that anyone who is brand new to off grid solar is a ‘dummy’ when they first start looking into it.

So, if you are an absolute newbie to this subject, then this article is for you.

Researching online and trying to find what you need, can lead down a rabbit hole and leave you dazed and confused.

Unless you’re a sparkie or a person who is fascinated by this subject for the sake of it (weird), then stop researching for a moment because this article will tell you everything you need to know and nothing you don’t.

At the very least, it could save a ton of time (and maybe some money).

If you’re the 1 in 100 people who wants to learn about depth-of-discharge rates of carbon vs lithium ferrous phosphate battery chemistry or half-cell monocrystaline PERC tech vs mono, you won’t find it here.

You are better to give us a call for that sort of stuff.

But first:

We can’t cover everything in this article.

That’s impossible.

Instead, we’ll talk about the basics in plain english to give you more knowledge and hopefully some direction.

The next step, if you have a project to get sorted, is to Book a Free Consultation over the phone or maybe a Zoom. It will cost you nothing and you’ll get your questions answered.

You can also request a detailed and customised report with pricing if that’s needed.

There is no charge for our design service.

Scroll down to dive in.

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1. We are not a good fit for everyone

Power Station New Zealand is not a good fit for everyone, and we may not be the right solution for you.

That’s OK.

If that turns out to be true, we hope you still get some good value out of this information.

There are many off grid component suppliers in New Zealand today. That’s exactly what they do – supply you with components.

That’s not us.

In most cases, you’ll pay a bit less to a component supplier, but it’s up to you to do the design calculations and arrange the install. You’ll need tons of time to research and manage the project, and most of the time you’re on your own (especially if something goes wrong).

As manufacturers, our systems are ‘plug and play’. We import components then assemble and test them in a prewired cabinet ready for the average sparkie to install.

Your system is customised for you. The design, education, ongoing support and follow up is part of the price.

Potentially, this will save you thousands off the install plus give you the peace-of-mind you’ll need in the unlikely event it all turns to custard.

Read on to learn the basics of how off grid solar works.

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2. How off grid solar works

If you already have a good grasp of the basics, you can skip ahead to the next section.

If you don’t know a lot, please read on.

Grid power, delivered by the government, started in Rotorua in 1901 with the Okere Falls Power Station.

Naturally there’s been an exponential growth in coverage and service quality since then, but the fact still remains that in large areas around New Zealand, there is no grid power available.

Sometimes it’s nearby and can be connected if you, the user, are prepared to pay.

More often than not, it will never be connected due to the topography, remoteness and economic cost.

Simply put, off grid power is any alternative to mains grid connected power that allows you to operate normal 230-240V appliances in a residential or business environment.

It could be a smokey old generator, solar, hydro, wind – or a mixture.

The concept of off grid solar

Here’s how it works in a nutshell:

    1. Generation
      Energy from the sun is collected by solar panels as direct current (DC)
    2. Distribution
      It’s sent to an all-in-one inverter/charger/controller unit where some of it is converted to alternating current (AC) and distributed to your switchboard to be consumed by your house, on-demand.
    3. Storage
      Some DC power collected by your solar panels will be sent to your battery bank to be stored and used later, when needed – after converting to AC power first.
    4. Access
      When the sun goes down, or on dark days where your power use is greater than the generation output of your solar panels, you’ll be using power stored in your battery bank.
    5. Cycle
      The cycle continues each day, assuming there is enough solar radiation to allow your solar panels to generate power.

An auto-start backup generator ensures your lights won’t go out and protects your battery bank from damage (more on this later).

On consecutive dark days when there’s minimal sun (low solar generation), and on days when you exceed your usual power load, the generator will automatically start for a short period of time to replenish the battery bank, then go back to sleep.

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3. Why are you looking at off grid solar?

It’s fair to say that most people looking at off grid solar are doing it because they have a house or business that is some distance away from mains power.

Sometimes it’s just not physically possible to get the power on.

And if it is possible, most people want to compare the cost of going off grid with the cost of getting the power connected.

Is that you?

Maybe you’ve already had a quote to get the power on, or a quote from another off grid solar company – and all you need now is an estimate to compare.

Deciding to go off the grid is not always about the money; there are other factors to consider such as sustainability and independence.

But for most people, it comes down to the dollars – and the financial viability.

And fair enough.

What’s your situation?

Let’s see if you fall in to one of these groups:

  • You own land (or are shopping for land) and want to build a house, tiny house or holiday home

  • You own land and want to relocate an existing house, tiny house or holiday home

  • You own land and are building a prefabricated house, tiny house or holiday home which will be relocated to your site on completion

  • You are already living off the grid and need to upgrade or replace your system

  • You own land and haven’t decided what type of dwelling to go for – you just want help to work out if it’s financially viable

  • You own land and want to run an accommodation (Airbnb?) or tourism business off the grid

  • You own whanau or hapu land and want to explore off grid solar as part of your papakainga or marae project

  • You are living overseas now, but are planning to return home and live off the grid

  • You’ve had a quote from another off grid solar company and want to compare value

If you tick one or more of these items above, then please read on.

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4. How to calculate the financial viability of off grid solar

If it’s cheaper to get the power on, sometimes connecting to the grid is a better option.

Of the hundreds of systems that we’ve designed and supplied over the years, the majority were because of the price (or impossibility) of getting hooked up to grid power.

For most people, off grid solar is a ‘grudge purchase’. In other words, if it weren’t for the fact that getting grid power connected cost more than going off the grid, they’d get the power on.

But just because it’s a grudge purchase, that it doesn’t mean your system shouldn’t be designed carefully.

It also doesn’t mean that you can’t have a reliable, quality system that delivers tremendous value.

Comparison

With off grid solar, you are independent which means no more monthly power bill.

Yay.

Don’t get too excited. What you’ll save in future power savings and lines fees, you’ll be paying in the up-front costs of the components, plus the back-up generator and the cost of the install.

Check out these examples:

But it’s not always about the money.

We have many clients who are not constrained by the budget and who still choose to live an off-grid lifestyle for their own reasons.

These include independence, freedom from paying a power bill as they head into retirement, environmental sustainability and more.

A small but growing number of clients are Preppers or Survivalists who have reasons that go well beyond the cost of getting connected.

For you, is it just about the money (which is OK with us), or do you see other benefits or reasons to go off the grid?

What size system do you need?

We could write an entire book on this subject (and probably will at some stage). But for now, the information below should be used as a guideline only.

If you take the next step and decide to get help, we’ll take you through a step-by-step process.

Here’s some rough ‘back-of-the-envelope’ sizing and prices you can expect.

The three main costs

There are three main areas that make up the price. They are:

  • The components themselves

  • The auto-start generator

  • The installation

The cost of the components is largely based on how many kWh (kilowatt hours) of power your house will use in a 24hr period.

Your location will also affect the price due to differing levels of sunshine hours around New Zealand. This will determine the number of solar panels needed and we use computer modelling based on official NIWA sunshine records.

The components consist of one or more inverter/charger/ controller units, your battery bank, the solar panels – and in our case, the cabinets, rails, fittings and other bits and pieces.

The generator could cost as much as $6,500 inc GST and the installation could start at $3,000 with an average of about $4,000 to $6,000 being common.

Post Covid-19, prices charged by qualified installers has increased in some areas. As manufacturers, we are independent of installers and work with you to find the best deal for a professional job.

Pricing Guideline (Components Only)

As a rough guideline only, the prices for the components could be:

  • Small House: $16,000-$22,000 inc GST
  • Medium House: $22,000 – $29,000 inc GST
  • Large House: $30,000 – $40,000 inc GST
  • Extra Large House: $40,000 – $50,000 + inc GST

How much for installation?

It is not possible to give you an accurate estimate of installation because of the large number of variables involved.

We’ll need time together over the phone to ask questions before we can give that to you.

And even then, there will need to be a Technical Site Visit conducted by the installer before an accurate quote can be provided.

Having said that, let’s guestimate $3,000 plus GST for the small house, $4-6,000 for a medium home, $7-9,000 for a large home and over $9,000 for an extra-large home.

The last step is to compare the price to get the power connected which is covered in the next section.

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5. How to get a quote to get connected to the grid

In the previous section we talked about estimated pricing of off grid systems and the cost of installation.

In this section, we’ll discuss how to organise getting a quote to get grid powered connected.

If there is no physical way of getting power connected to the property, then you can skip this section and move on to the next.

There are currently 27 lines companies in New Zealand. You need to call or email the company who manages your area and request a quote.

To see which company manages your region, go ahead and visit The Electricity Network Association (ENA) website which is the industry membership body.

As you can imagine, there are different factors that your lines company will take into consideration before giving you an estimate of the price. These include:

  • The distance from the nearest power source to your place

  • Whether or not a transformer box is needed to ensure your power supply is stable and sufficient

  • The cost of the cable, conduit, and other consumables

  • The cost of your meter box

You should also consider the distance from the point where the lines company terminates the power to the house site.

Typically, you’ll need to get a local electrician to give you a quote to run this final stretch.

If you need a lines company quote, do it early

We have seen the completion of brand-new houses and move-in dates being pushed back because owners have not organised quotes early enough.

Depending on your region, some lines companies can take weeks and even months to get a quote to you. They are often stretched by lack of resources.

The bottom line

How did you get on with your numbers and doing the comparison?

If it’s clearly cheaper to get the power on, if you are constrained by your budget, and you don’t see the value of going off the grid that other people see, then don’t do it (and you can stop reading).

But if it costs more to get the power on, or if you can see the value of doing it despite the expense, and you have the funds – then do it.

You’ve decided to do it – now what?

Now that you’ve decided to go off the grid, it’s time to get expert help.

Trying to accurately design and correctly size a modern off grid solar system on your own (assuming you are new to the subject), is like researching how to overhaul the engine of your new car then calling your mechanic with your instructions on how to do the work.

It will waste your time and annoy the mechanic.

But worse than that, if you happen to get the design and your calculations right, it will only be because of dumb luck.

In our experience there’s a very good chance that if you know little about it and try to do it yourself, you’ll get it wrong. Sorry.

If you don’t know what you don’t know, it’s only natural.

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6. Correctly sizing your system

In this section we’ll explore the range of factors that go in to getting your system sized correctly.

Some of these are critical to getting the correct result and some are not so important, but still relevant.

A correctly sized system ensures you don’t over capitalise. No one wants to over-spend, right?

But worse than that, an under-sized system can give up prematurely if it’s being asked to deliver more than it is engineered to provide.

Apart from the frustration, this can reduce its overall lifespan and decrease the value of your asset.

The list below is our starting point to calculating a correctly sized system for your unique situation:

  • How will you be managing your cooking, heating and hot water heating? If you expect your solar system to power all three, – this is possible – however your overall price could double or even triple compared to finding alternatives such as gas or solid fuel

  • What is your exact location? The latitude of your region determines the sunshine hours and therefore the correct number of solar panels you’ll need. We use specialised computer software to calculate this. There are also micro-climate considerations for a number of regions in New Zealand including Taupo, Manawatu, Wanaka and Southland. If you are from any of these regions, there are other issues to consider

  • What’s the age range and makeup of the family or occupants, and what are their typical habits when it comes to power use? You’ll be surprised how knowing this can affect your overall design

  • Do you need your system to be expandable in case your power needs change over time? If so, this can affect the battery technology we recommend and other factors

  • Will your power usage level increase, decrease or remain stable over the next 10 years? This can affect the type of battery technology we recommend and how we plan your solar panel array

  • Do you plan to own this dwelling for the long term? Will it be your ‘last home’? Your answer could affect the design and our recommendation

  • What is your ‘off-grid mindset’? You may be a careful and practical person, or you may be more carefree (or there may be both types living in your house). We need to know so we can explain what this means practically, and adjust your system parameters to suit, if needed

  • Is someone at home using power during the day? This can affect the size of the battery bank and we’ll explain why

  • Will you have a solar panel roof array or a ground array? Will you have one plane of panels facing north (ish), or will we need a ‘split array’ over two or more surfaces? There are pros and cons for each option which can affect the final price you pay. We can advise you

  • What is your roof type and pitch? Different roof construction types and angles will affect the overall price due to the potential for extra fittings and components

  • What will your total ‘load’ be at any one time? Depending on how many appliances are running at once and what their collective load will be, this will determine the type and number of inverter/charger/controller units you’ll need.

     

When we chat, we’ll cover a lot more areas that may not be so obvious.

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7. Affordability vs reality

Our first job is to design a system for your needs – not your budget.

If you want great value (who doesn’t?) but you are constrained by your available funds, then you have a few options.

They are:

  • Find a way to find the funds. Without exception, everyone regrets not buying a correctly-sized system down the track. In our view, secure and correctly-sized power supply should always come before the purchase of a spa pool, motor vehicles, carpets or even a garage. We have finance options available and you can talk to us to find out more

  • Downgrade to a smaller (and lower priced) system. It’s not a perfect solution, however if you are prepared to do without and rely on your generator more in winter until you can afford to add more panels or battery storage, this could be a good solution.

  • Try DIY off grid solar. Find a company that we call ‘component suppliers’ and see how you go. The price will be lower, but there’s a reason for that. If you go in with your eyes open, it may be the only solution for you.

A quick note: Please talk to us about any concerns with your budget or finance.

We can sometimes find creative ways to reduce your power load that may not be obvious (which means a smaller system), and we can give advice about your finance options.

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8. Which battery chemistry is best?

There’s no right answer to the question of which battery technology is best because it depends on several factors (we’ll cover these during our first phone meeting).

These include:

  • Whether your power needs might increase over time

  • You comfort level adopting to a new technology that may be less proven, vs older but proven technology

  • The physical space you have available

  • The pricing difference

Currently the best value in off grid solar battery chemistry (in our experience) is lead carbon and lithium ferrous phosphate (LFP).

Sure, there are other battery types coming on the market all the time. And as engineers, we like to keep abreast of those.

But we also don’t want you to be the guinea pig with new technology that could potentially explode the price of your system.

This article is not the place to go into the detail of the various differences, feature comparisons and relative advantages and disadvantages of each.

Talk to us to see what chemistry could be best for you.

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9. Which solar panels do you use?

It’s a common question to ask, but what people really mean when they ask about off grid solar panels, is:

  • Is the quality and technology of the panels good, relative to the industry today?

  • Will I get good overall value for money?

  • Can I trust that the solar panels will perform?

The good news is that most established solar companies in New Zealand (including Power Station and our parent company SolarKing.co.nz) provide top quality solar modules that are good value for money.

Our panels are manufactured by ‘Tier 1’ companies. Generally speaking, Tier 1 solar panel manufacturers are defined as those that:

  • Have been producing solar panels for five years or more

  • Are either publicly listed on a stock exchange or have a strong and stable balance sheet

  • Have fully automated production

  • Have a high degree of vertical integration

To view the full, independent and international list of Tier 1 manufacturers,,click here.

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10. Do I really need a generator?

Almost certainly.

People usually ask this question for two main reasons:

  • They think they’ll save money if they leave it out

  • They don’t want to pollute by burning fossil fuels in the form of petrol or diesel

We reckon most people are in the first category, but are happy to accept the need for a generator – once they understand the reasons.

Let’s cover that now.

As a manufacturer, we don’t sell generators (although you get access to wholesale rates though our contacts). Although we strongly recommend it, it’s your call whether you decide to connect a generator – or not.

For a start, most battery manufacturers require the generator connected – with a ‘two wire’ auto start connection fitted – so you don’t void your warranty.

The auto-start function protects you from the lights going out – and it protects your bank account because replacement battery banks are costly.

The logic

Due to the latitude of New Zealand (and unlike the tropics) there is considerable variation in sunshine hours between summer and winter.

You can see in the graph below that in Wellington, the monthly sunshine hour figure jumps up from 100 hours in June, to just under 250 hours in January.

These figures are sourced from official NIWA figures averaged over 15 years.

This extreme variation in sunshine hours means that with off grid solar, we need to size your system so that you can get through the month with the lowest sunshine hours.

That’s the month of June.

This means you’ll typically produce way more energy in summer than you’ll consume.

That’s why running a heat pump as an air conditioner or a swimming pool pump can work.

While all of that sounds good for summer, the problem is that no matter where you live in Aotearoa, there will be consecutive dark days with little or no sunshine in the winter months.

Yes, this even includes areas with traditionally high average sunshine hours such as Whakatane, Nelson, Blenheim, New Plymouth and Kaitaia.

Sunshine hours are officially averaged on a monthly and annual basis. For example, for the last 15 years Nelson enjoyed about 143 hours of sunshine in June, compared to Wellington’s 99 hours for the same month.

But just like every other region, Nelson will still experience two, three or even more days of dark weather in a row in June, without that affecting the region’s monthly or yearly average.

Long story short, we have to plan for consecutive days of no sun – because it can, and does happen.

Without the generator, the lights will go out after X number of days (depending on your load) because the solar panels can’t feed the battery bank.

It’s just physics.

Why not just add more panels and forget the generator?

It seems logical to just add more solar panels, until you realise you may have to double or even triple the number of solar panels you’d need.

That can be dear – and may cost more than the price of the generator.

But even with a shed-load of extra panel, there will be consecutive days in your region where there is almost zero sunshine.

It won’t matter how many solar panels you have; if there’s no light hitting them, all they are good for is a resting place for birds.

It gets worse…

Why not just add more battery storage and forget the generator?

This is a common question that again, sounds logical. The problem is that battery storage is the most expensive part of your system and the numbers won’t make sense.

Once you understand that if you add more battery storage, you must also add more generation (panels), then all of a sudden, the cost of the generator looks attractive compared to the alternatives.

What about wind?

Sometimes wind generation can make sense in certain situations, not to replace a generator, but as a way to supplement it.

It’s not a ‘must have’ in order go off the grid, and it may blow the budget when it comes to financial viability.

In our view, most people who insist on integrating wind generation into their off grid system do it because they like the idea of it – not necessarily because it might save money.

A standby generator will still be needed for windless days with no sunshine, unless you have an unlimited budget.

Talk to us about how wind generation could work for you.

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11. How many days of backup battery are needed?

When we talk about backup battery, we mean how many days of ‘normal living’ do you want to have during periods consecutive dark days before the generator starts.

We recommend one or two days.

Here’s an example of how it could work:

A typical example

Let’s say on Monday you enjoy a bright day, and the battery bank is full when the sun goes down. On Tuesday you wake up and it’s dark outside and remains that way until nightfall.

During the daytime on Tuesday there will be little or no solar generation which means the battery bank will not be replenished.

Your house is being powered solely by the battery bank (or what’s left of it). If your off grid solar system has been sized for one full day of battery backup, this means that at some stage on Tuesday evening or overnight on Wednesday morning, the battery will deplete completely.

If this happens, the system sends a signal to the generator to start up and it will begin to fill the battery bank. When full, it will turn off and ‘go back to sleep’ until called on again.

The length of time it takes to fill up depends on whatever load is running at the time, the size of the output of the generator (kVA) and the size of your battery bank.

If your system is sized for two days of battery backup, and if the bad weather continued into Wednesday, the generator would more than likely start on Wednesday evening or overnight Thursday morning.

Again, it would run for a short period then stop.

The cycle continues until the sun comes out when the solar panels ‘take over’ from the generator, until it is needed again.

How frequently the generator runs also depends on your ability to stick to your daily load evaluation in winter.

The first consideration is your budget – and whether the extra money is worth the benefit of the generator starting less often in winter.

As an example, adding a second full-day of battery backup could increase the size (and price) of your system by as much as 50%.

During our phone meeting, we’ll help you decide on how much backup battery is best for your situation.

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12. Conclusion & Thank you

If you’re reading this, you’ve made it to the end and deserve a lollipop!

We’ve only covered the basics here, but wanted to reinforce the importance of getting help early to avoid costly mistakes later down the track.

Today, because of giant leaps in technology in recent years, there is nothing stopping you from living a quality life off the grid in New Zealand.

But you have to go in to it with your eyes open.

The first step is to talk to the experts, especially if you are new to this subject.

Thank you for taking the time to read this.

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