5 things you need to know before installing Solar panels on your roof

Today solar rooftop photovoltaic (PV) systems become more popular than ever. Experts agree that having your own renewable solar pv or wind system is just a matter of time, if you didn’t install yet, you’ll definitely look for a contractor to develop it and commission it properly sooner or later.

The photo is for a solar installation by taqetna on the top of a villa in Amman, Jordan

The cost of solar insulation is falling while the number of installations are rising dramatically. On the other hand, the capacity of distribution networks are limited. We can conclude that the race is critical to reserve a place for your system on the grid.

1. Do you have enough space on your rooftop?

Usually when we contact our clients after receiving their inquiries on taqetna’s Go Solar page, we find that most people don’t have full understanding of the space needed for their proposed solar system; some of them think a few panels will be sufficient to reach their goals and some of them think that they need much more of what they really want.

To simplify this point, we can categories consumers into two segments;

  1. Small consumers, equipped by single phase power line from the electricity distribution company
  2. Large consumers, equipped by three-phase power line from the electricity distributor

For the first type, it is very simple to calculate and provide very accurate answer as the largest solar PV system allowed to be connected on this subscription is a 3.6KW inverter. This size of inverters can run up to 135% of solar panels depending on the manufacturer recommendations and the EPC contractor design. So, we are talking about 4.9KWp of solar panels can be installed on this subscription.

If we are going to install a 400W panel size, we are talking about 12 panels of a standard 72 cells MONO-PERC technology. This system requires around 34sqm including the shadow space between panels. So if you have more than 34sqm free at your rooftop, then you can install 4.8KWp solar PV system on it.

You can conclude that almost every 1KWp of solar panels requires 7.1sqm/KWp (for panels efficiency of ~20%)

Abdullah Shattel
Projects Engineer at Taqetna

For the second type; the large consumers who have three-phase subscriptions, they can install systems with capacity of 5KWp and more depending on their average electricity consumption.

For example, if your villa have an average electricity consumption of 1500KWh monthly, then the solar PV system capacity can be calculated calculated by dividing the average consumption on the average solar PV system production per KWp which is 130KWh monthly as follows:

Solar PV system size = 1500KWh/130KWh= 11.5KWp

Area required will be then: 11.5KWp x 7.1sqm/KWp =82sqm.

This gives an estimate of the needed space for solar PV systems for regular rooftop basic mounting installation.

2. Which solar panel technology is better for you

There are several solar cells technologies available in the market, classified according to the manufacturing process and raw materials used within cell layers.

Most of the solar panel options currently available fit in one of three types: monocrystalline, polycrystalline (also known as multi-crystalline), and thin-film. These solar panels vary in how they’re made, appearance, performance, costs, and the installations each are best suited for.

The following table compares between the dominant solar PV cell technologies available commercially in the market:

Solar panel typeEfficiency (ɳ)Cost ($)Warranty
Thin-Film10-17%MediumUp to 25 years
Polycrystalline15-20%LowUp to 25 years
Monocrystalline20-22%High25-30 years
Solar Panels Comparison Table
So, Which panel is better for you?

Our recommendation for all size of projects is to use the monocrystalline panels. Of all panel types, monocrystalline typically have the highest efficiencies and power capacity. Monocrystalline solar panels can reach efficiencies higher than 20 percent, while polycrystalline and Thin-Film solar panels usually have efficiencies between 15 to 17 percent.

3. Select your inverter wisely

The solar inverter is the most sophisticated part of any on-grid solar system and unfortunately it’s also the part most likely to have issues. This is not surprising considering inverters are usually located outside in harsh weather conditions including rain, humidity and extreme heat, all while generating thousands of watts of power for up to 10 hours a day. This is why it’s important to use a quality inverter and mount it in a sheltered location if possible.

Fronius and SMA have ranked on top of the list for many years due to the low failure rates and great service, as they usually ship replacement units in a short period of time. Both Fronius, SMA and ABB are available with 10 year warranties.

We in taqetna have installed and test top 3 ranked models and we usually recommend our clients to go with SMA inverters because they are:

  •  Good quality
  •  German & Chinese made
  •  Expensive but worthy
  •  Long & Proud History
  •  Efficient

4. Choose trustworthy contractor

Solar and wind industry have many complexities, some of them very subtle where experience counts for a lot. Doing the job right is unlikely to happen if you hire a general contractor or if you think you can DIY.

Choosing the right contractor for your system is more important than selecting the panels and inverter.

Always quote from local companies that have been in business for a long period of time and avoid newly established companies. You need to make sure the contractor will stay in business long enough to honor their workmanship warranty, and perform any additional repairs or maintenance in the future (like replacing the inverter halfway through the life of the system).

For example, taqetna has been in the solar and wind business for 10 years, supported with a proven track record reflects the ability to sustain and grow the business on the long term which means serving the clients’ solar/wind systems during the long warranty period.

5. Be aware of the Cost versus quality equation

It’s NOT smart to collect lot’s of quotes and listen to lot’s of sales people from so many contractors, this will create huge uncertainty and doubts in your conscience. This will delay your decision and prevents you from potential savings free energy. On the other hand, when you collect two-three quotes its easy to understand that the system is composed mainly of the thee main components (Solar PV panels, inverter(s) and mounting structure) and installation/contracting services. It is clearly explained in the points mentioned above how to tackle these items. The rest is simple, choosing the right price by asking your contractors to update their quotes according to your preferred panels, inverters and accessories. Then, start to do your due diligence on the contractor’s reputation by checking his track-record, references and customer service.

We hope that this article will help many home owners and businesses to understand the main pillars of solar systems and accelerate taking the right decision in investing in solar systems, which will help people to gain their expected savings sooner.

If you don’t have your owns solar or wind system at your home, every day is a loss!

Please don’t hesitate to contact us for any question and to get your quote, it takes only a minute to inquire

4 Comments

  1. Jalal Jawdat Al-Asfar

    السلام عليكم ورحمة الله وبركاته واسعد الله اوقاتكم بكل خير تحبونه وتتمنوه وبارك الله فيكم وفي جهودكم الطيبة للحفاظ على البيئة بتركيب أنظمة الطاقة المتجددة الشمسية وربنا يتمم على خير والمهم ان نحافظ على الجودة الشاملة واختيار افضل المكونات ذات الكفاءة العالية والاهتمام كذلك بتوفير معقول في فاتورة الكهرباء عبر الدراسات والحسابات الهندسية الفنية مما يساعد على اقتناع المواطنين بأهمية هذا النظام من أجل المحافظة على البيئة والتوفير كذلك والله يعطيكم العافية وجزاكم الله خيرا

    1. وعليكم السلام صديقنا جلال ، بارك الله فيك و كل الشكر على اهتمامك ودعمك لجهود استغلال الطاقة المتجددة للمساهمة في توفير كلف الكهرباء وتحسين البيئة من حولنا

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