Home Solar – Financially sound

The cost of installing solar panels has recently reduced, while electricity costs have increased. For many homes in Ngaio, investing in solar can be a smart financial investment. It may pay for itself in 4 years and provide free power for the following 20 years.

Several members of the Ngaio Climate crew have installed solar systems and are happy to share how they did it, what it cost, and what they save. Call Ross on 021 4040489, email ross@outdoor.co.nz or call in at our next event. Or check their solar system reviews.

Check out the Frequently Asked Questions on Solar.

For a guide on how to assess your home and get multiple independent quotes, check the How To Solar section below.

For reviews of solar systems on Ngaio houses, see reviews below.

– The returns are typically much better than investing in Kiwisaver. But they vary depending on the type of system you choose, your electricity retailer, your roof orientation and the time of day you use your electricity.
– Typically, systems recoup their entire cost in 5-8 years, and with batteries, can provide near-free electricity for a further 20 years.

– Solar panels on the roof (typically 12-20 panels generating 5-10kW)
– An Inverter that converts the DC power from the panels to 240V AC
– Optionally, a battery to store the power generated for when it’s needed.

– $10-$30,000.  5kW of panels can be as little as $10,000. A bigger system with batteries and the ability to run during a power outage might be $20-$30,000.
– We recommend talking to people in this group about their experiences with costs and savings.
– Loans are available at 1% interest.

In Ngaio, a reasonable estimate might be 450kWh per panel per year of usable electricity. But this will depend on the orientation and angle of your roof and the configuration of your system.

  • – The best returns come from north-facing roofs with a pitch of 30° or more. But flatter roofs and even East-West oriented roofs can provide good economic returns. 
  • – Installers will calculate the estimated power by month for your roof as part of their free quote, and it is easy to check the accuracy of this.
  • – Add a quick table of solar estimates by roof orientation and pitch in Ngaio.
  • – We recommend MySolarQuotes. They will ensure you get three free, no-obligation quotes from SEANZ members.
  • – You can also talk to our members about their experiences.
  • – The slowest part is usually making the decision. You should get quotes within two weeks. 
  • – Permits are required to be issued within 2 weeks.
  • – Installers may have a backlog of work (check when you are about to accept a quote).
  • -Installation normally takes 1-2 days, and you will generate electricity you can use as soon as it is inspected (within a week).
  • – Certification and the right to export (and get paid for) surplus power can take another month.
  • – Solar panels are probably the cheapest they will be. Manufacturing efficiency has plateaued, and there are no new technologies imminent. The USA’s imposition of 150% tariffs on solar panels left a surplus of manufacturing capacity for the rest of the world. Capacity has equalised and prices are climbing.
  • – Inverters are nearing or have achieved similar cost minimisation.
  • – Batteries for home storage are likely to reduce in price. But only slowly. 

Solar systems with batteries are often designed to work when the grid is down (they are called hybrid systems). Solar systems without batteries cannot work without the grid, even if the sun is shining.

  • – A battery lets you slide when you use your electricity during the day. Most particularly, it allows you to use your own electricity at peak times when prices are highest and the grid power used the most carbon.
  • – The grid can be used as your battery, but the price you sell electricity is typically half what you buy it back for.
  • – Batteries can have almost as good a financial return as solar panels only. They create more flexibility in when you use the solar power, and (if they are installed with a hybrid mode) they ensure your solar system works in a power outage. 
  • – It is a good idea for your roof to be ready for 25 years without further maintenance.  Rusty roof may be better being replaced first.  Otherwise, a fresh coat of paint on a steel roof will save money later.
  • – For other types of roof – tiles, flat roof etc, your prospective installers will advise on suitability and preparation.  

Quality installations appear to at least recoup their cost at house sale time and decrease the time to sell.  See our separate analysis for more details. 

Most of the major banks are offering 0% or1% loans for solar systems, efficient heating, home insulation and EVs. Westpac and ASB are offering up to $150,000 at 0% for 5 years.  ANZ and BNZ $80,000 at 1% for 3 years.

  • – There is a lot of misinformation about Solar. 
  • – The panels are made with materials that are abundant and are designed to last longer than a car. They are probably the least environmentally damaging form of power available to mankind.
  • – The modern, LiFePO4 batteries used in Solar systems are expected to last 14 years, are fully recyclable and use relatively abundant materials. They should not be confused with Li Cobalt batteries that require rare metals and are difficult to recycle.
  • – LiFePO4 batteries are not perfect, but they do far less damage to the environment, than our other energy alternatives.
  • – Sodium batteries are about to become available. These will in time, be cheaper and more environmentally friendly. But the initial pricing will not be much cheaper. 
  • – Your system will seamlessly switch from using solar electricity to using the battery and/or the grid.  
  • – In summer, most solar systems generate more power than the house can use. The surplus is sold to the power company and the credit used to buy extra winter power. Many households with solar can end up with a net credit for the year.
  • – Another way to use extra power is to heat hot water.  Hot water is often a third of the total electricity usage.  With a cylinder (as opposed to gas instant hot water), nearly all the hot water can be from the solar panels.

It probably wasn’t then.  Prices have dropped a lot in the last three years.  It is well worth getting a new quote.

Steps to Installing Home Solar

If you have a north-facing roof, someone is at home during the day and you own your own home, Solar is almost certain to be a strong financial investment. Get quotes.

If someone is at home during the day, the roof gets reasonable sun for much of the day and you own the house, solar will likely be a good investment. Get quotes.

If no one is home on most days, solar with batteries and a hot water diverter will still have a financial benefit.

If in doubt – talk to us at the Ngaio Climate Club.

My Solar Quotes is an independent company that will arrange 3 quotes from reputable suppliers. They also have more details on different types of solar systems. All the quotes received via My Solar Quotes will be from SEANZ members (Sustainable Energy Association of New Zealand).

There are numerous Solar installers serving Ngaio, but we recommend ensuring they are SEANZ members.

It is likely that the quotes will be based on satellite images of your home and will be subject to a site inspection before finalisation.

Ngaio Climate Crew (NCC) can assist with this.

The quotes will estimate your average power generation for each month of the year. These tend to be accurate, but NCC can assist by comparing them against NIWAs records of sunshine hours and solar PV panel performance in Wellington.

The quotes will suggest savings that can be achieved on your power bills (most installers will ask for copies of your bills before quoting). NCC can assist you in calculating what savings you are likely to make.

There will likely be several different types of systems offered. Particularly with or without batteries. Batteries enable the system to run during power cuts (Systems without batteries won’t work in a power cut, even if the sun is shining). Batteries take a bit longer to pay for themselves. Still, with Time of Use metering about to become a major part of the NZ electricity supply regime, the payback time is shortening.

Ensure price completeness. Does the roof need maintenance before the job starts? Is a meter or switchboard upgrade required? Suppliers are generally good at advising of these things during the quote process.

With all the major banks offering loans at 0-1 % and usually with no establishment fees, It makes economic sense to take a loan.

There may be a 4-8 week delay before installation can start. The supplier should take care of all permits and approvals.

Typically, the installation will take 1-2 days. Certification may take a further week. Meter upgrades to sell surplus power back may take a little longer again.

This is a critical step. Buyback prices range from 8c to 17c. Time of Use plans can further cut your power costs, sometimes further halving them.

Your inverter will come with an Internet-connected phone app to monitor usage and power generation. Check that it is delivering the power promised, that you are using the power when you expected and that the retail electricity plan is the right one for you.

Making a few tweaks at this stage is common. But after that, sit back and enjoy the savings.

Solar Examples in Ngaio

PV Capacity  – 18 x  405W panels for 7.3kw nominal capacity.

System Type We chose a hybrid system, expecting a slightly lower return than panels only, but wanting resilience from power cuts.

The inverter is only 5kW, so it can’t convert the last bits of the panels’ electricity to AC power at midday in summer. But we don’t need the power then, and it’s efficient in winter.

Battery capacity 7.3 kWh (6.5 usable).

Cost The quote was for $22,000 installed. A meter change to support exporting power to the grid was a further $160. There were no additional fees from the installer.

Savings The installer correctly estimated the electricity that would be generated on a monthly basis. So far, we have 1% difference between actual and estimated. We generate about 9,000 kWh a year.

The installers’ estimates of usage, costs and buyback prices were not accurate. However, we will have a net-negative electricity bill for the current 12 months. We are also planning to replace our gas hot water, which will increase our power savings to well beyond the estimated $2,400 p.a.

The installer’s quote estimated an IRR of 13.53% and a payback time of 8 years 1 month.  Based on the current performance, we will do better than that.

Installer Solar Worx – We would use them again.

Electrification state. Before and after PV install:

We were a low-volume user of electricity with piped gas hot water and limited use of gas home heating. A wood burner is our main source of winter heating.

We have a PHEV (plug-in hybrid car) that we charge on a standard 3-pin plug in the garage.

Having seen the savings and power generation from our solar system, we are replacing our gas systems with electrical ones.

We currently use Electric Kiwi as our electricity retailer. We recharge our batteries at 6 am in winter, using our free hour of power to ensure we have free power through the morning.

We installed our PV system in 2022.  W started researching late 2021, settled on a supplier and the install was scheduled for March. Once completed, we then had to wait about 4 weeks until the installation was signed off by an independent certifier.  

We wanted a PV system that could continue to operate in the event of a grid outage so that we could also provide basic power for ourselves, and neighbours.  (Not all PV systems have this capability).  This also meant that we had to identify the essential circuits to be linked in to the uninterrupted power supply (UPS).  For us this was fridge/freezer, oven, lighting, and a few key power circuits to router etc.

  1. PV Capacity  – 18 Trina Vertex 385W panels for 6.9Kw nominal capacity. We have 6 North-facing and 12 West-facing panels 
  2. System Type We have a hybrid system, with a 6kW Inverter and a 10kWh battery
  1. Cost. We were initially quoted for 16 panels, but while the crew were installing, we saw there was room for an extra 2 panels, so added them at the time. After 3 months there was a problem with the initially installed inverter and battery, the system was down for two months before an upgraded inverter and battery were installed.  Our providers, Lightforce, were generous in compensating us for the disruption. This system has been running well for nearly 3 years since September 2022. The final cost for our installed system was $31,600. Our installers, Lightforce, reimbursed the cost of upgrading our meter to an import/export meter. Lightforce also covered the cost of the inspection to sign off and commission the system so it could go live.
  1. Production info since September 2022:
    1. Our baseline annual grid consumption prior to going solar was around 6.2MWh. In the time our PV system has been running, our annual power consumption has remained largely unchanged, while our annual grid consumption has reduced by 80% to around 1.3MWh. 
    2. Annual generation has averaged 8MWh, 
    3. Exported power to the grid has averaged 3.2MWh
  1. Electrification state. We have a conventional electric hot water cylinder, electric ovens, a pellet burner heater, and currently have bottled gas hobs. We purchased an EV in 2023 which we now largely charge at home using trickle charge. We will probably replace our gas hobs with an induction hob
  1. Current Electricity Retailer. After purchasing our EV in 2023, we signed up with Meridian’s EV plan which offered a $300 credit on a 24 month plan, a night rate of 16.7 c/unit, and solar buyback @ 12c/unit. We’ll probably review this when the current plan expires and see what else is on offer
  2. I’ve been looking at our total energy spend across bottled gas, wood pellets, electricity, and petrol.  After installing PV, the annual average total cost has gone down from $3,900 to $2,200.
  1. We’re both retired and are home during the day
  1. Solar Supplier – We contacted three suppliers, got quotes from two, and went with Lightforce.  One of the main reasons for going with them was that they do their own installation and support so that we’re not having to deal with different parties.  We’ve found them very responsive when issues have arisen.

What would you do differently? If we were a family, we might add East-facing panels to start generating earlier in the day, and possibly a few more West/SW panels to continue generating longer in the evenings.

We installed our PV system in 2014.

PV Capacity: 12 Canadian Solar CS6P 250W panels for 3Kw capacity.
System Type: Grid-tied (no battery)
Cost: We were initially quoted $9995 fully installed, however, we opted for a different inverter to the one that was quoted, and paid a total of $10,995.  The upgraded inverter was able to give us reporting on generation, which was important to us.  
Installer:  The installer was Righthouse, which is no longer trading.
Savings:  We initially calculated that the system would pay itself back in 15 years, based on our usage and electricity rates at the time.  Several factors have affected this over the last 11 years.
 – 6 months after our install, Meridian (at the time the best option for solar buy-back) cut their buyback rate from 25c/kwh to 7c/kwh.  
 – lines charges have increased dramatically (the daily charge for the privilege of being connected to the grid, irrespective of usage).  
 – our family size has increased, with a corresponding increase in daily usage

 – power prices have increased much faster than anticipated
For the first few years we tracked our generation and usage diligently, however it is now very much back of mind.  We no longer obsess over the minutiae but have peace of mind knowing that the PV system is quietly saving us money everyday.  It is likely that the system has already paid for itself.
Electrification state: We use conventional electric hot water,  and primary heating is from a wood burner and heatpump.  Prior to the PV install the heatpump was used in winter only.  Now we will often use it guilt free for cooling on hot summer days.  We purchased an EV in 2022.