Solar Now – Free Guide to Solar PV for Homeowners and SME’s

You have decided to invest in solar photovoltaics, and this is a good decision.

To help you get the most out of your investment we have produced this free guide for your benefit, and so that you continue making good decisions on your choice of installation company.

From reading the small print, to discussions with your insurance company, this guide offers a simple list of 12 things to consider when investing in solar PV for your home or business.

1. Read the small-print, and Test any claims.

This is a basic investment rule, so if you are already engaged in this process, please read the small print from any company offering to install solar PV panels on your property.

Do investigate any specific claims being made by the installer. You can always contact us if you have any questions.

All too frequently we come across websites making exaggerated and sometimes ridiculous claims as to potential savings, % return on investment, the length or type of warranties in effect, and other important details relating to your significant investment.

Like any other investment decision, you should take all necessary steps to ensure the quality of your investment for yourself.

2. Be a PROSUMER – determine how much electricity you can prosume

The amount of electricity your solar PV system can produce is not so important as how much electricity you can consume.

For homeowners, the objective should be to use the electricity produced which facilitates a substantial reduction of household bills. If your utility company has a high-mix of fossil fuels then you will also reduce your carbon footprint in the process.

The amount of electricity your solar PV system produces is based on your location + your choice of components + the quality of installation.

The amount of electricity you prosume (produce + consume) is also based on how much solar energy is captured by your battery to be used at your convenience. Therefore, it is important to choose a good quality battery.

Ireland is currently the most expensive country in Europe per unit of electricity before taxation is included, and among the most expensive countries for the retail price of electricity when taxes and levies are added [1]. The most expensive countries for electricity are currently Ireland, Belgium, Denmark and Germany where the average retail price ranges from 25.5 – 32.5 cents/kWhr.

Yet for small-scale (< 30 kWp) rooftop solar PV systems with battery storage, it’s possible to produce electricity for ~ 8 – 19 cents/kWhr according to researchers at the Fraunhofer Institute [2] [3]. This seems a large difference for a product we are buying thousands of every year.

3. Forget feed-in tariffs for now

Although feed-in tariffs are being discussed in various places, and they are legally mandated for future implementation (possibly in Q4 2022) the likely scenario is that they will be very small, expensive to implement, and will not generate much return for the average household or business.

The current government policy on micro-generation indicates a tax exemption of €200 per household, per annum relating to any income received on the CEG scheme (from January 2022). The size of the exemption indicates government expectations of what consumers might hope to earn from the scheme.

Aside from environmental triggers, the best reason to install a solar PV system for your home or business is the large difference between the cost of producing your own electricity VS. the cost of purchasing your electricity at high retail prices into the future.

4. Ensure good quality components

Once you have decided for solar PV, choosing good quality components is important.

Often the homeowner does not get to select the components rather they are offered a package deal, so if your installer is offering low-quality components, you should choose a different installer.

You are entering into a long-term relationship where quality is key.

The solar energy market is growing at a phenomenal pace in Europe and globally, circumstances which mean there are many new entrants and new low-cost suppliers in the marketplace HOWEVER these are not the best suppliers to choose on cost alone.

The supplier should be financially robust enough to be around in 30 years time. The products should have a large enough installation base to verify the quality of the product and to see how the supply-chain handles component failures.

5. Never mix-and-match components yourself

In solar engineering, components are NOT plug-and-play. Although one component may work with another, or may appear to work with another at first, they should be individually tested and matched using a variety of technical information best left to a qualified engineer.

Never mix-and-match components yourself.

The solar module itself is highly temperature dependent. The higher the operating temperature the lower the output. This operational window needs to be correctly matched to the operational window of the associated power electronics components in your solar PV system.

To operate at it’s best, the solar module needs to be well ventilated, and this also applies to the inverter and battery components, and therefore the correct installation becomes a very important element of the project over the long term

6. Choosing a good solar panel installation company

(Steps 6 thru 10)

As a homeowner or a business owner, you have already asked yourself whether solar PV panels are right for your unique property or business. A simple evaluation of your property might help you to verify the potential outcome for you.

Homeowners still need to follow the same basic rules as you would for any installation company or contractor doing work at your home, ie. seek references for previous work done, and examine the terms being offered in the installation contract.

There are four main elements to consider in a solar PV system.

1. Choice of solar module
2. Selection of an appropriate good quality inverter
3. Selection and sizing of battery
4. Choice of installation company

Often these choices are pre-selected by the installation company and their suppliers. If your installation company is offering low quality components to begin with, you will certainly benefit from further research.

7. Choose solar modules with a strong warranty

When it comes to solar panel manufacturers, a strong warranty is indicative of a Tier 1 company, with a robust financial framework and distribution network supporting the product.

Based on the length of warranty offered, and the performance characteristics of the solar modules, we would ideally select modules from Sunpower, LG or Recom [4] where they are available.

Alternative solar panels with strong warranties, and slightly lower performance data are manufactured by Trina, Longi and Canadian Solar – all of which should be widely available for your project.

There are a number of newer players in the market offering solar modules with product warranties of up to 20 years. As these are newer companies, we have left them out of our consideration for the time being.

All of the companies mentioned in this section are manufacturing solar panels with around 20% efficiency for p-type crystalline-Silicon solar modules [5].

3 parts to the warranty on a solar panel

There are a three parts to the warranty on a solar module; which relate to the physical product itself, the long-term performance of the product, and the guaranteed power output after a specified number of years.

1. Product Warranty
2. Performance Warranty
3. Power Warranty

The best or most desirable solar panels currently offer a 25 year product warranty, with a 25 year performance warranty, offering above 90% output power after 25 years. These kinds of warranties are available with solar modules from SunPower, LG and Recom (Tier 1 manufacturers).

The next strata of suppliers offer a minimum 12 year product warranty with a 25 year performance warranty, offering around 84% output power after 25 years. Products offering these kinds of warranties are currently available from Trina, Longi and Canadian Solar.

Choose a good quality module with a comprehensive warranty and the solar module can reasonably be expected to last the lifetime of your project. Although there can be issues with solar modules after a period of time it is the least costly element of your project and the most likely component to last for 25 years.

Example 1 – Examination of solar panel warranties

The product warranty is the principal warranty on the solar module.

Manufacturers in Group 1 include SunPower, LG, and Recom.
Manufacturers in Group 2 include Trina, Longi and Canadian Solar.

Ensure that the installation company is not attempting to sell you on the performance warranty alone as every performance warranty should cover 25 years.

Solar Now recommends that a minimum product warranty of 12 to 15 years should be sought on solar modules.

8. Choose a good quality inverter from a strong manufacturer

ABB is a strong European manufacturer with a long history in the electricity production market. Their products have been used in the Irish grid for decades and many technicians are already familiar with their equipment. ABB produce a wide range of power electronics equipment suitable for use in both domestic and commercial solar PV applications. Wherever possible we consider using ABB inverters and associated equipment.

Alongside ABB there are a number of other players producing good quality, widely-used and efficient inverters, such as Victron, Fronius, Solis and others.

There are also a number of Hybrid products where the inverter component is built collectively with another component such as a battery. Manufacturers in this space also include Huawei and the highly regarded Sonnen GmbH.

9. Select a good quality battery

The battery is usually the most expensive component of a solar PV system and it is important to choose wisely.

The battery is also the component which is helping to maximise the amount of electricity you prosume and therefore increases (or potentially decreases) the return on your investment.

For battery products there are few companies offering a better product than Sonnen GmbH, who have been in production for over a decade, have a very large number of current installations in Europe, consistently rank among the best manufacturers in the industry, and offer a very long product life for their Lithium-Iron-Phosphate (LiFePo4), or LFP batteries.

Sonnen GmbH currently offer a 10 year or 10,000 cycle warranty on their products. If the technical parameters allow, we will usually choose a Sonnen.

There are several imitators of the Sonnen battery, ie. new manufacturers who list very similar characteristics to the German company, but having examined several of these suppliers we still maintain that Sonnen offer the best quality domestic batteries on the market.

One parameter which will impact your choice, is that a battery with a 5 year warranty may need to be changed twice as often as a battery with a 10 year warranty. This needs to be considered under the lifetime costs of your investment.

Example 3 – A Comparison of Battery Warranties

Batteries are a finite resource that need to be replaced from time-to-time.

Battery A is a 3.5 kWhr battery with a 5 year / 6,000 cycle warranty.
Battery B is a 3.2 kWhr battery with a 10 year / 10,000 cycle warranty.

The initial purchase price of Battery B is greater than Battery A.

Over the lifetime of your project you will need to purchase at least 2 x Battery A, which has a lower specified lifespan, therefore the minimum input costs for battery A
Total Cost of Battery A = 2 x Initial Cost.

Given it’s longer warranty, due to the quality of manufacture and higher lifecycle specifications, Battery B has a much higher probability of lasting through the lifetime of your project.
Total Cost of Battery B = 1 x Initial Cost.

Which battery is better value?

Manufacturers put considerable effort into their warranty documents, which reflect the strength of the product. If 5 years is the best warranty period a battery manufacturer can offer the consumer should continue their research.

The phrase “buyer beware” applies in particular to high value items, but also to items which you expect to last a long period of time.

10. Ensure the mounting system is up to the job

The choice of mounting system, or the supplier of your mounting system is another critical component not just for utility scale developments but also for homeowners and businesses.

Choosing the correct mounting system can increase the electrical output over the lifetime of the project by significant values.

Every mounting system should be modelled and pre-tested for wind-loading variables, and other environmental extremes.

11. Project Lifetime

25 years is generally considered to be the lifetime of a solar PV project. This is the usual timeframe for planning applications, product warranties and operational budgets for any solar PV project.

Now is the best time to go solar, but the benefits should last you a lifetime.

12. Consult your Insurance Company

It is useful to make an enquiry with your insurance company if you are installing a solar photovoltaic system at your property.

Aside from the cost of replacement if things go wrong, or in the event of an adverse incident, your insurance company may be able to provide advice on the type of insurance you need for your investment and whether your new solar PV system is covered under your normal home insurance contract.

In Summary

We wish you well on your journey with solar photovoltaics, which is a critical component of Ireland’s carbon neutrality strategy.

Everyone can play their part with solar PV, which is currently the cheapest way to produce electricity according to the experts.

Feel free to contact us with any questions you may have.