May 27, 2019

Things to check when buying solar panels for your house?

The deployment of solar panels in residential sector is at a all time high with good system pricing due to government incentive, low interest finance, market competition and high electricity tariffs. With the solar retailers hunting for any solar sales, price war and sneaky marketing require attention. How to make the right decision with solar. […]

The deployment of solar panels in residential sector is at a all time high with good system pricing due to government incentive, low interest finance, market competition and high electricity tariffs. With the solar retailers hunting for any solar sales, price war and sneaky marketing require attention.

How to make the right decision with solar.

You, the customer may feel that it is a simple process of contacting some solar companies for quotes and in return, you get bombarded with multiple quotes of various system sizes, different solar panels all claiming to be the best and a large percentage decrease in the electricity bill. This leads to confusion.

Reading the following article, one asks the question, if all solar panels are tested to the international standard, why are there failures?

Well, solar panel failure is one of many issues that can occur. Ideally you want to pay for a solar system that will operate for 25 years without any major failure and will reduce the electricity bill as promised.

Based on my 20 years of experience in the solar industry, being part of many project deliveries, quality audit and engineering system for clients, the following is my guidance;

Solar panels : The quality of the solar panels in the market have been good in the last couple of years, with most solar companies offering Bloomberg tier 1 listed panels which is a manufacturers bankable qualification process. For standard 60 cell crystalline solar panels rating, the 280W is the point of demarcation, any panels lower then 280W uses older cells with lower efficiency. My recommendation is to go for 280W or higher panel rating.

Inverters : There are 2 groups of inverters available in the market. My trusted brands are ABB, SMA, Huawei, Fronius, Enphase and Solaredge. These are some of the globally recognized high performing inverters that can last an average of 12 years in the Australian climate. Then there are other inverters brands classed as entry level. These inverters are cheaper because they may have any combination of lower cost of manufacture, cheaper electronic components, limited R&D budget, lower efficiency & performance with wear & tear of components, basic warranty coverage, less testing during manufacture and less features etc. My recommendation is the trusted brand of inverters with a 10 year full warranty on parts and labor. You may also find a 5+5 year warranty which is first 5 years full replacement warranty the the next 5 years does not cover labor cost for replacement.

System design: The term AC:DC ratio represents the inverter power rating over the total solar panel power rating. Typical example being a 6.6kW solar system with a 5kW inverter. Solar companies are simply maximising the amount of solar panels that can be connected and still be above the minimum of 75% ratio to claim the government incentive (5/6.6= 75.7%). This low ratio can cause restrictions to solar energy generation in the summer months (eg. solar capability is 6.6kW but the inverter will only allow 5kW production). My recommendation is to have a AC:DC ratio above 85%.

Product Warranty claim: There are 2 product  warranties (solar panels, inverter) that is very important to consider. Standard solar panel comes with a 10-12 year product warranty and a 25 year performance warranty. This is a standard warranty that all solar companies will present. You also need to know what will be the warranty process if the solar panel fails and the solar manufacturer is no longer manufacturing. Good solar manufacturers will have in place a third party insurance process that will guarantee that the warranty is honored. With the inverters, a 10 year full warranty means that you will not pay for the replacement if the inverter fails within 10 years. But you should also be mindful that many manufacturers disappear hence investing in a good inverter and manufacturer makes sense. Some manufacturers offer a 5+5 year warranty whereby if the inverter fails in year 6, then the manufacturer only supplies while you have to arrange an installer to install it. A 5kW inverter replacement cost outside its warranty period can be $1,500.00 or more.

Workmanship warranty: This is something not discussed during the sales process but is most important. Poor workmanship can contribute to a much higher failure rate of the solar system.  Lets face it, there are good installers who have the experience and passion to install a system at its best. Then there are installers who will cut corners to finish the install within a specified time because any work outside the contracted time means that they will lose money. Poor workmanship can be bad electrical termination, dodgy equipment installation and carelessness on the roof leading to water leakages. The industry standard workmanship warranty is 5 years and some may offer 10 years. Workmanship warranty means nothing if the solar company goes out of business (common issue) and  in the case of a fault can cost you almost almost $500 to get an electrician onsite to only diagnose a fault and additional cost to repair or replace equipment. My recommendation is to research on the solar company, see reviews on google & facebook, check ABN details for operational time (minimum 3 years), Clean Energy Council retailer list.

System performance: The whole reason why solar panels are installed is to reduce the electricity bill. The solar companies take the daily energy use data (eg 28kWh/day) from the electricity bill, Quickly decide how much energy is consumed during the day (eg. “someone at home” means 60% x 28kWh = 16.8kWh used during the day) and this based on a 4 sun-peak hours (16.8kWh/4) means a 4kW system with the obvious upsell to 5kW or even 6.6kW. You already know that solar cannot provide energy in the night hence a battery addition in the future is possible so investing in a slightly bigger solar system size isn’t a bad idea. But most important of all is to understand the economics. The solar system is an investment and hence there shall be a return. The solar company needs to provide a very clear and accurate solar panel layout drawings, monthly energy yield data, estimated decrease in  the electricity bill for each of the month and the payback period. A good solar company will invest its time in giving you a proposal with all these data rather then giving you just a price. My recommendation is to get a formal quotation with all energy modelling and economic modelling details. Payback period shall not be more then 4 years. Once the solar system is installed and you receive your electricity bill, get the solar company to prove that the system performance based on the reduction on the new electricity bill is validated.

System monitoring: Monitoring of the system is very important as this gives you eyes on the system. Some monitoring system records the solar energy produced , compares it with the weather data of the location and informs you on a daily basis how the system is performing. You can also record the load data hence seeing the bigger picture of the whole energy profile which will give you all the information on the requirement of the batteries. This data is also important when dealing with the solar company who provided the system and is responsible for the energy generation based on their own modelling. My recommendation is that a monitoring system eg Solar analytics is a very important equipment that can improve the system performance and better savings. On average a third party monitoring system can cost $500 but can easily pay itself back within the first year.

Remember: When you are buying a solar system for your house, included in the cost are solar panels, inverter, electrical materials, workmanship, warranties, system performance, reliability and assurance.

A solar company achieves a cheap price by presenting “best of the worst” solar panels and inverter, poor installation, no time on comprehensive proposal, no time on economic modelling, no intentions on upholding warranty and doesn’t intend to be operational in the market long term.

The above information all clearly presented by the solar company means that they have taken time to present a site specific proposal rather then a generic price quotation.