The Ultimate Solar Panel Buyers Guide

Over the past few years, there have been a lot of companies ranging from landscape designers to installers of windows, roofs, air conditioners, fire alarms, etc. magically retrained as installers of solar and backup power systems. There are even former storekeepers who are now “solar energy professionals.”

When you talk to companies like these, you may notice that they have similarities. Some will say that they have been working with solar panels and equipment for autonomous power supply for many years (or even decades). Almost everyone will assure them that they offer the best products on the market and that they provide “the best calculations.” Often, to facilitate the sale, such sellers offer cheap low-quality equipment – or clearly low quality or does not meet the requirements for equipment for reliable power supply systems. It is not known how long such equipment will work, but with a high probability, it will be much less than the declared service life. This applies to all elements of the system – both solar panels and inverters, chargers, controllers, batteries, etc.

When buying solar panels and related equipment, there is a well-known rule – buy from those who can correctly design and calculate the power supply system, and who installs the equipment that sells. If a company installs equipment, it means that:

1. it bears guarantee obligations for the operation of the installed equipment and is responsible for the result, and not for the quality of individual elements. So that later there would be no nasty situations.
2. It is unprofitable for a seller who bears warranty obligations for an installed product to sell a low-quality product. It is beneficial for him that the system works without breakdowns, and all the elements give out the declared parameters during the entire warranty period for the product.
3. A seller who is not responsible for the result can sell a low-quality product, attracting buyers at a low price. Unfortunately, an ordinary buyer cannot check the quality and parameters of solar panels – he can only trust the seller and the manufacturer. Check the compliance of solar panel parameters declared without special equipment is impossible. Therefore, if you are offered only solar modules, you have a high risk of buying a product that will not work as expected, and its reliability will be low. Quality and reliability issues are especially important when purchasing solar photovoltaic modules – after all, they have a service life of more than 25-30 years. To save 20-30% when buying a solar panel and get a non-working module in a few years – agree, it’s a shame. Moreover, if the seller’s warranty is required by law for 1 year from the date of sale.
4. Please note that installing solar modules is also quite troublesome and time-consuming. If a low-quality module starts to “junk” in a year or two, you will have to spend energy and/or funds to identify the breakdown. This requires a knowledgeable solar module electrician who will have to check all the circuits of your solar panel – and this, depending on the complexity of installation and access to the panels, can be a daunting task.
5. A miscalculated system is another “danger” of running out of electricity from your solar system. Our engineers “ate the dog” when calculating solar power systems, they have to calculate several systems every day, they have all the necessary data both on solar resources and equipment parameters. They know which equipment is reliable and suitable for a specific task.
6. The tricky plan – learn more, buy cheaper elsewhere. Some “tricky” clients call on professionals for their advice, but buy equipment somewhere cheaper. Unfortunately, such a “trick” when buying a solar power system does not work. The competition is quite tough on the market, and it is almost impossible to buy a product (solar panel, batteries, inverter, etc.) of the same quality much cheaper than ours. Replacement with analogs is fraught with a loss of reliability and a discrepancy between the real and declared parameters of the power supply system. When calculating a power supply system with solar panels and other renewable energy sources, there are a lot of nuances that an ordinary buyer does not even know about.

An analogy can be drawn here: if a doctor prescribes a medicine for you, you can buy almost the same one, with the same active ingredient, but with a different name, and it can be much cheaper. But what do you tell the doctor if this cheaper medicine does not help you or even, God forbid, does harm?

How Does Solar Energy Work?

The sun is the original source of all energy, and we can all benefit from its resources. But how do solar panels work? How does something as simple as a solar panel take sunlight and use it to power your oven, television, and even your Xbox?

Basically what happens is that your solar panel system uses photons to separate electrons from atoms. Photons are particles of light. The process of separating electrons from their atoms creates solar electricity.

Now let’s learn more about how solar panels work.

These are the five steps that you should know:

1 – Solar panels capture sunlight

Each solar panel contains photovoltaic (PV) cells. PV cells take light, or photons, and convert it to solar electricity. When sunlight hits the solar panel, PV cells produce direct current (DC) electricity. (Hey… want to learn more about the science behind this? See NASA explanation ).

This is all great — but DC electricity cannot power your home on its own. This is where other pieces of solar energy equipment come in. Let’s move on to solar inverters!

2 – Inverters convert solar energy to useful electricity

Some solar panel system configurations have a single inverter (often referred to as a “string” inverter) for the entire system. Some have a microinverter attached to the back of each solar panel. The most important thing to know about inverters is that they convert DC electricity from solar panels to alternating current (AC) electricity. This electricity is what powers your home. We are coming.

3 – Solar electricity is used in the house.

Electricity runs through your net meter, makes you comfortable in your home, and energizes your appliances. It works like your traditional electricity works today — you don’t have to change a thing. If your solar panels don’t produce enough power to cover all your electrical needs, don’t worry. You are still connected to the traditional public company through the network, so you can take more power from your public company when you need it, automatically. What if you produce more electrical energy than you consume? Let’s see.

4 – Surplus solar electricity goes to the public grid

It might seem counterintuitive to stay connected to the traditional utility grid if you have a solar power system, but staying connected to the utility grid has its benefits. It allows you to use as much electricity as you need before sending any excess solar energy to your utility. Solar panels generate electricity when the sun is shining, but we use electricity at night too, when we are not producing solar energy. That is why it is important to stay connected to the public network. It works like this:

5 – Solar Electricity is measured by the net meter

For this last part, you will need to know what a net metering contract is. Net metering is when your public company agrees to give you energy credits for any surplus electricity that you produce and deliver to the public grid. In some cases, these energy credits may remain in effect so that you can accumulate them over the long term, and some public companies will even write you a check for the energy production credits.

The net metering device is installed in the house and measures the electricity coming and going from the public grid. This meter is similar to the electric meter you probably have today, but it measures energy going in two directions, instead of just one. Do you have any more questions?

A note on net measurement

It is important to note that if you have a shared PPA contract in which you pay for the solar energy that your panels produce, you will probably pay more for your solar energy in the summer. This would appear to be the other way around, right? Let us explain: Summer means more sunlight, which means more solar production. BUT the good news is that since you are less reliant on traditional electricity, it should result in a lower total electric bill.

Now add to that the value of accumulating net metering credits, and while it might seem slow at first, it ends up saving you money in the long run. About twelve months after installing your solar power system, you may begin to see the net metering process tilt in your favor.

What Are The Types Of Existing Photovoltaic Systems?

Photovoltaic system interconnected to the electricity grid 

The energy produced by the photovoltaic system is for self-consumption. In the event that production exceeds consumption, the surplus is injected into the electrical grid. Likewise, if consumption exceeds the production of the photovoltaic system, the supply is obtained from the grid. 

Here comes the first problem that we have to solve … not all appliances are on all day and when they are used they do not require the same consumption for the power they require. For example, a refrigerator is on 24 hours a day while a clothes dryer can be used for a few minutes. 

The microwave has a high consumption of kilowatts, but it is used for a few minutes every day, so when using one of these products consumption grows exponentially and if we had to analyze at that time our calculations would not be the real ones. 

That is why we have taken all these weights so that the average can be made with the least amount of statistical error.

Next, we show you how much we have taken from each electrical appliance so that you take it into account in case there is a different amount in your house so that you can add or subtract it from this list.  

Calculate the average Daily Electric Consumption

(Watts of power consumption x hours of monthly use / 1000) = average monthly kwh

Based on this formula we will see each of the cases that we can have:

• An average 15 cubic foot refrigerator has usage of 240 hours per month (8 hours per day) and an average consumption of 300 watts per hour. That is, for this refrigerator the monthly use of kilowatt-hours is 72 kWh ( 290 watts x 240 hours / 1000 = 72 kWh). 

Now if we consider a larger refrigerator, for example, one of 20 cubic feet, its average consumption increases to 90 kWh. We can do the same calculation for the different appliances that we have at home, for example:

• For a small 1 Ton air conditioner, with an average power of 1160 watts that is used for about 300 hours per month (10 hours a day), its kilowatt-hour consumption would be 340 kWh  (1160 watts x 300 hours / 1000)
• For an LCD television between 32 and 43 inches we are going to suppose that we use it 6 hours a day, that is 180 hours a month, and assuming an average power of 250 watts, the result that we will obtain for its consumption would be 45 kWh (250 watts x 180 hours / 1000)
• If in our house we have a laptop and we use it an average of 6 hours a day (180 hours a month) we will obtain an average consumption of 63.5 watts per hour, which will translate into a monthly consumption of 11.43 Kwh  (63.5 watts x 180 hours / 1000)
• In addition, if we have the internet at home, we will necessarily have to consider the consumption of the router, which can be around 20 Watts per hour, so if we have it on throughout the month (720 hours), we would have a consumption of 14.4 Kwh  (20 watts x 720 hours / 1000)
• The iron, with a required power of 1200 watts and use of about 5 hours a month, would represent an average consumption of 6 kWh (1200 watts x 5 hours / 1000)
• In the case of a washing center, we would have a combination of 2600 Watts from the Washer and 5600 Watts from the Electric Dryer for a total of 8200 watts of power. If we use the laundry center about twice a week (8 per month), we would have a consumption of 65.6 Kwh (8200 watts x 8 hrs / 1000).
• Finally, for a microwave with a power of 1200 watts and average use of 8 hours per month, we would have an approximate consumption of 9.6 Kwh  (1200 watts x 8 hours / 1000)

If we add the consumption of all the appliances mentioned above, we would have the following

340 Kwh + 45 Kwh + 11.43 Kwh + 14.4 Kwh + 6 Kwh + 65.6 Kwh + 9.6 Kwh = 492.03 Kwh 

Which would be our monthly consumption, that is, 492.03 kilowatt-hours , with which our average daily consumption would be: 16,401 Kwh

Calculate the Power of our Solar Panels

Once we know exactly our consumption, we need to know the power necessary to satisfy this consumption. For this, we need to take into account some factors such as:

• The power generated by the solar panel: which varies depending on the manufacturer, type and dimensions of the photovoltaic cells. In general, there are panels that generate powers from 15W, 80W, 100W, 150W, 250W, 260W, 300W, etc.
• System Efficiency:  Generally, the conversion efficiency of 80% is estimated, that is, 20% of the solar energy will be considered a voltage loss, so it will not be used and will be discarded.
• Number of Hours with Sun:  For this, it will be necessary to know the average time of hours of sun in the place where the system will be installed. It is worth mentioning that this number will vary depending on the geographical location and the time of year. You can use this calculator to find the average number of hours of sunshine in a given location.

Having these data at hand, we can use the following formula to determine the real power generated per hour, for each photovoltaic panel:

(Solar Panel Power * System Efficiency * Solar Resource) / 1000 = KWh Generated per Day

For example, if we have a solar panel with a capacity to generate 250 W of power, and we would like to install it in the city of Monterrey, where there are about 5.91 hours of direct sunlight, we would have the following:

(250 W x 80% x 5.91 hrs) / 1000 = 1.18 Kwh

In other words, that Solar Panel would have the capacity to generate 1.18 Kwh.

Calculate the number of Photovoltaic Panels needed

Now, having this data, we only have to calculate the number of solar panels we need to cover all the energy consumption of our home. To do so, simply apply the following formula:

Average Daily Consumption / Panel Generation = Panels Needed

Then we will have:

16.40 Kwh / 1.18 Kwh = 13.89 -> 14 Panels 

This would be how we would obtain the number of solar panels necessary to cover our domestic or commercial electricity consumption. Here it is important to emphasize to make the calculation, we need to make a list of ALL the electrical appliances or equipment that we are sure we will need in our home, to size our photovoltaic system in a more accurate way.

How many Solar Panels do I need for an Air Conditioner?

Air conditioners do work with solar energy, but to make their consumption more efficient it is necessary to make detailed calculations as shown above. Here, it is worth mentioning that the efficiency of energy consumption in air conditioners varies depending on the brand, the cooling capacity and the technology of the same.

On the other hand, it is important to emphasize that good planning of the cooling and ventilation system must be carried out (taking into account the height of the room, walls, m3 to be cooled, etc.), to maximize the efficiency of the air conditioners to be installed in the home. or business, and with this ensures the efficient use of the energy generated by the photovoltaic panels.

Currently there are air conditioning units with powers ranging from 600 Watts to 12000 Watts, however, taking an AC of 3,500 Watts (one of the most common) as an example, it would have a consumption of approximately:

3500 Watts x 8 Hours per day / 1000 = 28 Kwh

If, for example, we wanted to use a panel with a power of 150 kW, it would generate

(150 kw x 80% x 5.91 hrs / 1000) = 0.709 Kwh

and therefore we would need:

28 Kwh / 0.709 Kwh = 40 panels

to generate the necessary demand for air conditioning

Now, if instead of using panels with 150 W power, we use 300 W panels, then we would need 20 Panels

How many Solar Panels do I need for a Refrigerator?

Regarding the subject of the refrigerator, we have analyzed that a 15 cubic foot refrigerator has a power of 290 watts, assuming that it has a general consumption of 8 hours a day (we consider these data since all refrigerators have a system in which it starts the engine when it reaches a limit temperature and turns off when it reaches its lower limit) that is, it consumes 70-kilowatt hours. 

In order to make a refrigerator work, we will need approximately 1 to 2 panels, according to the use we give it, always depending on the climatic factors and the geographical area in which we install it.

How many Solar Panels do I need for a TV?

For a television whose consumption is 180 hours per month, it will have a consumption in kilowatt hours of 45, for this we will need 1 solar panel .  

We have considered in our analysis a television with LED technology, since a computer with an LCD system is no longer so common in the market (but if you have one of the latter, the calculation will not vary too much, since its consumption is practically the same)

The calculation is based on televisions between 32 and 43 inches, if you have a larger television in terms of screen size you will not have problems, because a solar panel has the capacity to generate more energy than that required by a common television analyzed above. .

If we add a console we will not need to buy an additional solar panel since the energy demand of this equipment will be covered by what it generates 1 photovoltaic panel.

However, it is recommended that if you have a Home Theater, Modem, Video Game Console, and Television equipment, 2 solar panels be installed to meet the demand required by this equipment.

How many Solar Panels do I need for a Computer?

In the case of computers or desktop computers, it does not have much analysis since the same devices have an approximate consumption of 36-kilowatt hours per month. With a solar panel, you can easily run a computer.

But, since we generally use computers with other equipment, for example, a printer or a screen much larger than a common monitor, we will not have problems adding all these computer sets to a solar panel.

How many Solar Panels do I need for a water pump?

A very common issue in rural areas or places with water problems especially is this question of how many solar panels do I need to be able to run a water pump. 

Points to take into account in our analysis in order to make a correct calculation:

• The water pump has different powers, which vary the flow of water that they are capable of moving. 
• Also for the calculation, the level of water consumption must be taken into account, by this we mean that if a house does not consume a lot of water its level will not drop quickly, therefore, the pump will be activated less frequently, thus consuming lower energy. 
• It is also necessary to present the length of the pipes from where the pump is to the tank or the point where the water will be. 
• The capacity they have to conduct the cables, in terms of amperage. 
• The place of unevenness where the tank is located will also depend to be able to perform the calculation well.

If we consider a 1 HP 50 watt 3 amp water pump, approximately one-kilowatt hour of consumption per month will be needed. With a solar panel, the water pump will work perfectly.

How many Solar Panels do I need for a pool? 

If there is something in which solar energy is a useful tool for people’s comfort, it is pool heating. 

In order to make a calculation as accurate as possible we will have to consider:

• The amount of water in the pool
• The temperature at which you want to keep the water 
• The climatic factor of the geographical area where it is located 
• And since it works with a water pump, everything we saw in the previous point. 

If you want to heat a 90,000-liter pool in a cold area, you will need approximately 24 solar panels, while for a warm area to heat the water on average you will need 18 solar panels.

For a pool of 100000 liters, a work of 8 hours per day of the air conditioner we will need between 20 and 22 solar panels depending on the temperature of the geographical area.

12 Advantages of using photovoltaic solar energy

Solar panels are undoubtedly one of the best options to take advantage of solar energy. To see the importance of this type of energy, we must take into account that in a single hour the sun radiates enough solar energy to cover the consumption of human energy for a year.

In recent years there have been many advances in solar power system technologies. However, we are still behind in the methods of capturing this enormous amount of energy. Even though it is free and natural.

Here we are going to review some basic advantages and disadvantages of solar photovoltaic panels. To understand the pros of photovoltaic systems and the pros and cons of solar panels for the home, pay attention to the keys that we tell you below.

Advantages of photovoltaic solar energy 

From 1 to 6

1. Photovoltaic solar energy panels provide clean and ecological energy. During the generation of electricity with photovoltaic panels, there are no harmful emissions of greenhouse gases, so this type of energy is respectful with the environment.
2. Solar energy is supplied by nature so it is free and abundant!
3. Energy from the sun can be available almost anywhere there is sun.
4. It is energy especially suitable for smart grids with distributed energy generation.
5. The cost of solar panels is falling rapidly and is expected to continue to decline in the coming years. Photovoltaic solar panels have a very promising future, both for economic viability and for environmental sustainability.
6. Photovoltaic solar energy panels, through the photoelectric phenomenon, produce electricity directly through electricity generation.

From 7 to 12

1. The operating and maintenance costs of photovoltaic panels are considered low. Almost negligible, compared to the costs of other renewable energy systems.
2. Photovoltaic panels have no mechanically moving parts, except in the cases of mechanical solar tracking bases. Because of this, they have much less breakage and require less maintenance than other renewable energy systems (for example, wind turbines).
3. Photovoltaic panels are totally silent and do not produce any type of noise. Therefore, they are a perfect solution for urban areas and residential applications.
4. Solar energy matches the energy needs to cool photovoltaic panels. This is why it can provide an efficient solution to power demand peaks.
5. Although the prices of solar panels have seen a drastic reduction in recent years, and are still falling, photovoltaic solar energy could be further promoted through government funding.
6. Residential solar panels are easy to install on rooftops or on the ground without interference in the residential lifestyle.

In summary

Photovoltaic solar energy is making its way into the energy industry. More and more consumers are taking advantage of green energy. They do it to power their homes and businesses and lower their electricity bills. But is it worth investing in solar energy? And more specifically, what happens with photovoltaic systems? Do they really deliver? Of course, they are a tremendously attractive option in the long term.