Photovoltaic installation – how to choose?

Table of contents

Which photovoltaic installation should I choose?

When deciding on purchase and installation of a photovoltaic system we want to make the right choice.

We rush to the action of acquiring knowledge, spending hours on the web, where we try to obtain as much information as possible on our own (when that day comes, and the salesman stands at our door, we should be ready, so most of us think). Rankings keep us dreaming at night, and the number of index cards makes us dizzy.

Meanwhile, all we need to do is fill out the chart prepared for this purpose during the interview and avoid 99% percent of future trouble.

We are looking to the end of the Companies that answer all the questions positively, only later the price can decide the choice.

I want to reassure you, there are Companies that meet the set criteria (and even exceed them), while being quite reasonable with regard to the proposed prices. All “slip-ups” should be carefully considered, the more negative answers, the worse and more failure-prone our installation may be.

bid analysis sheet pdf – download attachment

Table of contents

  • Photovoltaic installation – how to choose?
  • Photovoltaic panels – product warranty
  • Photovoltaic panels – power warranty
  • Photovoltaic panels – additional information
  • Inverter – basic warranty
  • Microinverter – basic warranty
  • Residual current circuit breaker
  • Overcurrent protection
  • Isolating disconnector
  • AC surge arrester T1T2 or T2 depending on roof covering
  • DC surge arrester T1T2 or T2 depending on roof covering
  • Does the Company take an advance payment before starting the work?
  • Does the Company take an advance payment before starting installation ?
  • Does the Company take over the manufacturers warranty (Panels and Inverters)?
  • Within what timeframe will the Company take any action in case of a defect/failure?
  • Did the offer include all the necessary attachments – technical sheets of panels, inverter, text of the contract?

Photovoltaic panels – product warranty

More important than the power warranty.

It defines the duration of the manufacturer’s liability for any physical defects in the product, which can interfere with or simply turn our panel into a useless sheet. Ideally, the product warranty should be for the same length of time as the power warranty.

Often the product warranty is offered in 10,12-year periods. a 15-year product warranty is already a good result, according to many dealers. In our opinion, a good product is one that has at least a 20-year product warranty.

Photovoltaic panels – power warranty

Also called a linear warranty, for performance.

Cells lose their efficiency over time. It can be generally assumed that the loss of power ranges from 0.5% to less than 1% per year.

After 20-25 years, our panel will have an efficiency of about 80%. There are manufacturers who state efficiency after 25 years at 85% and higher.

There are also those who declare 85% efficiency on the panel after 25 years, but give a 10-year warranty on the product itself….

While the physical defect is easy to identify (remember: the product warranty is more important), it will be very difficult to prove that the power, however, is weaker than declared.

In our opinion: the performance warranty is a minimum of 25 years.

Photovoltaic panels – additional information

The choice of panels causes the most trouble, it is worthwhile for a few issues to be clarified. Panels made with glass/glass technology are the safest, because they are non-combustible (they do not have a film on the back like other models).

They are slightly more expensive than the others, but it is worth considering very seriously buying them.

Thehalf-cut cell gives very good results, it does not overheat like the standard ones, plus it is more durable and long-lasting.

Asmaller sized panel is better than a larger sized panel. A large panel will be under more pressure than a smaller one, manufacturers are introducing larger sizes cutting costs. While on farms a large panel is an obvious solution, on a home installation it is rather a misunderstanding.

On a dark roof a panel in a dark frame 🙂

Aesthetics is the key to satisfaction. After all, our house is supposed to be nice. Ask about the color.

instalacja fotowoltaiczna, moduł bauer solar
PV module Bauer 385 W

Inverter – basic warranty

The heart of the system (unless we use Microinverters).

An inverter is a device whose task is to convert direct current (DC) into alternating current (AC), that is, the one we have in our outlets.

The market standard now seems to be at least a 10-year warranty.

Very good and appreciated by some customers is Fronius. Unfortunately, the Austrian manufacturer only gives a 5-year warranty which can be extended to 7 years. In our opinion, this is not enough.

In many cases we can extend the warranty for a fee, even to 20 years, it is necessary to ask about the price of extension and the conditions that must be met (for example, until when I can decide to extend the warranty).

Service must be provided in Poland, be sure to ask about service procedures.

Hypontech inverter

Microinverter – basic warranty

With this technology, alternating current (AC) flows directly from the roof.

The risk of fire is virtually non-existent.

The undisputed leader in the world is the American Enphase, with a 25-year warranty.

In Poland, the Chinese Hoymiles is very popular, with a 12-year basic warranty (but extendable to 25 years).

This is a cheaper, but also a solid option.

Microinverters are perfect for areas with varying shading, troublesome location of panels. In case we have a roof without shading, only the highest security function remains.

We can observe the operation of each panel separately, in case of a fault in one of them, we will immediately observe the replacement.


Residual current circuit breaker

A very important anti-shock device. As the name suggests, it detects the difference between the current that flows into it and that which flows out of it. If the values are not equal, it means a network failure – the circuit is disconnected.

A mandatory component of installation protection, although it is not always recommended. If the person offering us a solution will not be able to explain the operation of the residual current circuit breaker, it may mean that the company the salesman represents does not care properly about his professional background. It can also be worse, that is, the circuit breaker will not be in our kit.

It should be remembered : the residual current circuit breaker is to be!

Overcurrent protection

That is, protection against the effects of short circuits and overloads (an overcurrent circuit breaker is, among other things, the popular “plug” or “fuse”).

This is primarily to protect our inverter. In the event of a short circuit, it will save the expensive device, so it is an essential component of our installation. It has an arc extinguishing chamber.

In our opinion, it simply must be and period.

Isolating disconnector

Another strange name. The operation of the disconnector is simple, it gives the ability to completely disconnect the power supply.

Often overlooked by installers.

The device does not particularly increase safety, but it gives the ability to disconnect the inverter (inverter) from the power supply, for example, in case of fire.

Also must be a component of our installation.

DC surge arrester T1T2 or T2 depending on the roof covering

Without going into details, depending on whether the roof has a lightning protection system or not, a suitable surge arrester must be used.

When photovoltaics began its adventure often high-end equipment was protected by the cheapest arresters. Today the industry is well educated and we are unlikely to encounter surprises in this regard.

They are used by everyone, so if the salesman did not know what it was about, I would rather not recommend the next steps.

Does the company take a down payment before starting work?

And does a room painter or electrician take an advance before starting his work?

Rather not, and let it stay that way.

Those who correctly and reliably perform their work and, most importantly, do not have any cash flow problems, can offer the customer a complete service without reaching out for money at the start.

Let a red light go on when we hear about advance payments or “per project” fees.

We pay after the work is done.

Does the Company charge an advance before the installation ?

A common practice

The salesman informs us that according to the contract, it is necessary to pay up to 60%-80% of the contract value on the day of assembling the kit components (mainly panels) at the customer. Because he has to order them and other such strange stories….

Wait a minute, I don’t have anything on the roof yet, and I already have to hand over most of the payment. In this situation, if the installation is done badly, I have no way to effectively defend myself.

There is no agreement

We pay after the work is done.

Does the Company take over the manufacturers warranty (Panels and Inverters)?

Very interesting question.

Who will service the installed equipment ?

Ideally, it will be the company that installed the installation.

The relevant provision in the contract on assumption of manufacturer’s warranty is very rare, but it occurs.

When the bidder presents us with a provision on assumption of warranty obligations, we will be dealing with someone special.

Within what timeframe will the Company take any action in case of a defect/failure?

When a breakdown occurs, what is the path of action and is it written in the contract?

Who has checked in the contract provisions for this point?

Well, exactly.

Response to a malfunction should be provided, the service technician does not have to come to us right away.

Most faults are related to customers’ problems with logging in, refreshing applications, etc.

However, when a more serious obstacle occurs, the service up to 3 working days working days should stand at our doorstep 🙂

Did the offer includeall the necessary attachments – technical sheets of panels, inverter, text of the contract?

Phew, finally the end 🙂

When we receive satisfactory answers to all questions, and back after the first visit of the salesman we receive a FULL PACKAGE OF INFORMATION to our e-mail box, along with the price offer, we can sit comfortably in an armchair and think about the choice.

When we have questions, let’s ask. When we can choose, let’s choose.





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