In this article I talk about a On-Grid Photovoltaic System used for Microgeneration of energy, which converts sunlight into electrical energy and feeds all home fixtures. The excess energy is sent to the network of energy utility, generating credits that can be used to pay for the energy consumed during the night, on rainy days or even at the times of greatest consumption where the energy generated by the system is not enough.
I recently got one of these systems, and decided to report my experience, because when I was to purchase it, I searched a lot of information on the Internet and have not found. Most of the information is in companies that sell such systems, and tend to be too optimistic, In addition to omit values and technical details. So here I intend to spend a client's vision, system user, pointing out the advantages and disadvantages of having a, the technical details of the system and the numbers, both the generation/consumption as the financial.
What is Microgeneration of energy?
When it comes to solar energy, many people already think of water heaters and the economy with electric shower. This is done with solar panels and boiler, and is the most common way to harness solar energy.
But what many people do not yet know is that it is possible to use solar energy to generate electricity, and so food not just the shower, but all the fixtures of the house, with a very large reduction in the electric bill.
In 2012, ANEEL regulated in Brazil microgeração and to minigeração energy and clearing system. A microgeração It consists of generators with an installed capacity of up to 75 kW, and to minigeração in generators with an installed capacity of up to 5 MW. for residences, what matters is the microgeração. My system, for example, é 3,6 kWp. This means that in times of more intense sunshine, my system will be generating 3,6 kW, which is more than enough to feed the electrical equipment of my house, except when the shower or some equipment more “Gastao” is linked. But as they get connected soon, overall balance 3,6 kWp is enough for me.
The clearing system It is what allows the surplus energy generated by our systems is injected into the utility grid, for use by other customers, and generating credits for us. These credits can be used to pay for the energy we consume network, when our system is not working or is not cope with the demand.
This clearing system It is essential to enable solar energy for, for obvious reasons, ela é gerada apenas durante o dia, mas também precisamos de energia elétrica durante a noite. É claro que poderíamos usar baterias e ficar totalmente livres da concessionária, mas baterias são caras e duram poucos anos. Isso inviabilizaria o sistema financeiramente. O mesmo vale para energia eólica, pois ventos também são intermitentes e ainda não temos tecnologia para “estocar vento” como dizia uma certa ex-presidente (desculpem, não resisti 🙂 ). Hidrelétricas não tem este problema, pois com as barragens armazenam a água, e deixam ela passar pelas turbinas apenas na quantidade suficiente para gerar a energia necessária, conforme a demanda, em qualquer dia ou horário.
Os Componentes do Sistemas Fotovoltaicos On-Grid
At On-Grid Photovoltaic System It is composed of two main components: photovoltaic panels and an inverter. Let's talk about each of them.
The photovoltaic panels receive sunlight and transform it into electricity. They are similar to those used in that warm water systems, But instead of heating the water generate electricity. They are usually in greater quantity, to meet the energy needs of the whole house. In urban areas they are typically installed on rooftops.
The number of panels depends on the system capacity. In my system 3,6 kWp are 11 panels 2 x 1 metro. In this way, they occupy an area slightly larger than 22 square meters on the roof.
The panels in question are the Canadian Solar, model CS6U-330P. For the specification, each generates a maximum power of 330W. multiply by 11 and came to 3,63 kWp of my system. The generated current is continuous. In optimal functioning, this current reaches 8,88A with a 37,2V tension. Plates are connected in series. Therefore, the voltage can reach 409,2V.
The plates receive the seal of Procel, and receive the rating A, attributed to higher efficiency products. In the seal shown that energy efficiency is 16,99%, the power of 330W, and the average monthly production of energy 41,29 kWh / month. I do not know exactly how they got this value, as much influence on production: the weather, the position in which the plates have been installed, Brazil's region in which they are installed, among other.
If the estimate is correct, the whole system, with 11 plates, make 454,19 kWh / month. My system generated exactly 488,4 kWh in January and 476,3 kWh in February, considered by the above average Procel. Whereas in February has 3 days less, February production was actually higher, despite the shorter days. January was a very rainy month, which explains the difference. Of course I can not extrapolate these measurements to the rest of the year, because by June the days will be getting shorter, and thereafter will increasingly long, to arrive in December. On the other hand, the months of autumn and winter are less rainy. Anyway, the system appears to be suitable for those who consume around 500 kWh / month, as I'll explain later.
The installation can be made into various types of roof. Mine is of ceramic tiles, with wooden frame. In this case broke through the tiles to hold the brackets in your own wood. The supports have thread auto-atarraxante and rubbers for sealing the tile at the hole. That way the burden is on the wood panels, and not on the tiles. They are not too heavy, It has aluminum frame. Most of the weight should be on account of toughened glass.
Ideally the roof must have space for the panels stand side by side, so that they are connected in series with the whip. It is possible to make jumpers, but the installers don't seem to really like them. They call a set of plates mounted side-by-side table. In my case they used two tables, a with 6 panels and others with 5, and they made a jumper from one to another, because there was no room for 11 side-by-side panels. On the roof in question there were no obstacles (antennas, etc.), What prevented the use of jumpers Additional.
The roofs are ideal for solar panels are those facing north, so have the highest incidence of Sun possible. Is it possible to install the panels on roofs facing East or West, but in this case there is a loss of about 15% a 20%, by the Sun of the early morning or late afternoon that shall not directly. You should not install the panels on South-facing roofs. These directions naturally apply to installations in the southern hemisphere, where is most of Brazil. In the northern hemisphere is the opposite, You must install the panels on South-facing roofs. In my case, the entire roof of the shed is north facing, allowing an installation with the ideal positioning.
It is worth mentioning that the system also works on cloudy days or even rainy days, but the amount of energy generated is quite smaller than a sunny day.
My system has panels guarantee 10 years, and an estimated useful life of about 25 years.
The VFD and the String Box
The VFD is another essential item of a photovoltaic system, as it is he who converts the direct current which reaches of photovoltaic panels to alternating current, We use in our equipment. In Brazil there is a large salad of voltage standards. In my region, and specifically in my residence, get two phases of 127V, also called biphasic 220V. So, the inverter takes care of converting the alternating current direct current 127V, in two phases. In regions that use single-phase 220V must use another type of inverter, of course.
My inverter system also is the Canadian Solar, CSI model-5 k-MTL. He works with a maximum input voltage of current of 15A 550V. The input voltage can vary between 80V and 550V. The output is at 220V, 50Hz or 60 Hz (in Brazil we use 60 Hz). Maximum output power of 5000W and 22, 7A. The power factor is > 0,99. Protection index IP65, which means that he is fully protected against dust and water jets protected. As my system is 3,6 kWp, I can still add more solar panels if you want to enlarge it, without having to mess with the inverter.
Looking at the photo of the inverter, We can see that in your lower left there are two wires coming in: black and Red. They're coming to DC power generated by solar panels. On the right side we have three wires: the two phases and the neutral, connected to the home network, where alternating current is injected.
The white device attached on the underside of the inverter is a dongle Optional WiFi. With he configured, the inverter continuously sends all system data to an online service, that can be accessed via mobile application or a web service to gain access to charts and statistics of our power generation system. I'll talk about them later.
The frequency inverter works with solar energy itself. In the late afternoon, When the sun goes down, It turns off automatically. The next morning, He turns on automatically. There is a switch to turn it off, but you just have to move on it in case of system maintenance. He also has an LCD display, that shows various information about the system. It's pretty quiet, make a slight noise when in operation, but almost imperceptible.
This frequency inverter Canadian Solar It is guaranteed for 5 years, maintenance-free and your life expectancy is the same solar panels.
It is worth mentioning that, for safety, the drive only works when there is AC power present in the output. That means that, even if you're a Sun splitting, the system will not generate power if the network the company discontinue the provision. This avoids accidents involving employees of the concessionaire, you could receive an electrical shock from the customers with grid connection when doing maintenance on the network of the concessionaire.
The box to the left side of the VFD is a string box. Is a protection that insulates the photovoltaic panels, preventing electric accidents. Inside there's a circuit breaker and a few DPS – surge protection device, that divert any discharges to ground. For some reason that I don't understand, the electrician who did the installation used the neutral wire as grounding, instead of the proper grounding wire.
The box on the right side of the VFD is just a circuit breaker box, You can interrupt the AC input/output inverter. The breakers normally only need to be turned off in case of maintenance, and will only disarm in case of outbreaks. Never stirred in my.
The small metal pipe between the two boxes only serves to take the neutral wire to the Spring box, It is used as a grounding. Aluminum housings of plaques are interconnected and linked to the neutral, in case of electric shock. Again, I don't know why they didn't use the proper grounding wire…
The larger metal pipe coming out of the Spring box (the left side) go to the slab. He's passing the wiring that brings direct current from solar panels. The metal pipe greater than right side is what leads to alternating current, already converted by inverter, for the electric network of the House. Drivers tend to be apparent because typically there is no ready conduits for this application in the houses, and the installers usually only apparent installation, in other words, they take care of boring slab, but are not breaking walls.
Before installation I had doubts if the alternating current could be derived from any point on the network, If it would have to be the main circuit breakers, the main circuit breaker box or even of any circuit breaker box. I even tried to question the surveyors who come to analyze the requirements of home, roof, etc. before buying the system, but they didn't know how to respond.
As I wanted to put the system in shed, the ideal was connects it in the shed circuit breakers, that is not the main box, because it is derived from the main circuit breaker box, that is in the House. If I had to connect the system in main box, would have to take more wiring to shed and no conduits for this. Fearing the inviability of the system, I've calculated the current that he could use. Are a maximum of 3600W divided into two phases of 127V, so a maximum of 14, 17A. As the cables going from the main breaker to the shed's are 16 mm, This chain is peaceful for them.
I was hoping, but on the day of installation, the electrician has confirmed that could pick up the network at any point. And so took my circuit breakers box ' cottage. Took bus direct, without circuit breakers, because the system itself already has circuit breakers in that little box on the right, as we have seen.
Another question that puzzled me was the location for installing the inverter and other equipment. The Inspector spoke on a wall with a width of 1 Metro available. Said it could be in the backyard, even in the open. The eaves of the House would protect a little, but he still would get Sun and rain. Protection IP65 inverter theoretically allows it. But to ensure I've been determined to install indoors, in a small Hall. The electrician installing confirmed that the installation would have to be indoors. This was done.
To make use of renewable energy is need to change the conventional power meter for a bi-directional meter. The bi-directional meter account both the energy consumed by the customer, as the injected, for the credits may be counted.
Microgeneration systems, the company makes the meter Exchange without cost. But, It is worth mentioning that they were somewhat curled up and took to make this Exchange, that ended up taking place nearly a month after the installation of the system. Furthermore, they sent a couple of employees who refused to show identification at the gate of the condominium, What is safety standard. With that they left without performing the service twice, further delaying the installation.
The Mobile Application and Web Service
As previously mentioned, the inverter frequency Canadian Solar It has a dongle Optional WiFi, which in my case came with the system. when set, it periodically sends the information to a server in the cloud. Through a web site or an application for Android or iOS, We can access information about our system, Statistics, graphics, etc. This not so we access the data directly on the device, and you can access them anywhere and any time, even at night when the drive is off.
The site in question is the http://www.smten.com/. It is the fastest, still has some flaws, more works. It should be noted that some graphs are 1 hours early, because I had not set the time zone to GMT-3 after the end of daylight saving time.
This is my Dashboard today:
It can also see the daily production, monthly production, among other:
We can see detailed graphs and export data to spreadsheets:
Here we see the Datalog configured and active, with the last accessed Info:
In this other tab, You can generate graphs, zoom at specific points and also exports them in PNG format:
You can also set up an e-mail and receive data in a spreadsheet periodically.
As for the application, he calls SMTEN and is available for Android and iOS. No Android, despite the manual say that it is available in Play Store, he is not. I had to download the .apk's own website and install it manually. The application basically shows the same information that the site, but usually faster. I not tested the iOS app.
How Much Does System?
This is the critical point of On-Grid Photovoltaic System and is probably the reason why this type of system is still not very widespread. A system 3,6 kWp like mine currently costs about R $ 21.500, including all equipment and installation.
In online stores I have not found the equipment Canadian Solar, but I found systems 3,25 kWp (10 plates) and 3,9 kWp (12 plates) da Centrium Energy, costing R $ 17.124,72 and R $ 18.924,31, respectively. then add the installation cost and easy got in R $ 21.500.
My Latest 3 bills before the system installation cost about R $ 350 each. After installation, this figure fell to around R $ 60,00. In other words, are over 6 years just to pay the system, and only then the economy would begin to appear.
It is a very high investment and long return. Could be advantageous with some kind of funding also at least 5 years, but I do not know if there is something. Unfortunately our government does not seem to matter much to promote the use of own power generation and the use of cleaner energy, which would relieve the hydro, reduce the use of plants and their damn flag red yellow additional, and possibly would also reduce the constant blackouts.
For example, the Germany receives considerably less sunlight than the Brazil. The site sunnier from Germany still gets less Sun than the less sunny location of Brazil. Nevertheless, the Germany's leader in photovoltaics. To encourage the use of auto generation, the energy generated by customers worth up to 7 times more than the energy provided by the concessionaire. In other words, the client only needs to generate one-seventh of what it consumes to reset the account. In Brazil is 1 to 1 and still you can't reset, as we will see later. This is another case where the Germany literally beats of Brazil 7 a 1. There, the regulation of micro generation also came out well before. Brazil is always late, at all.
But not everything is lost. I did not pay the full amount of the system! It happens that there is a resolution of ANEEL (ANEEL Resolution No. 556/2013), which requires utilities to invest in “Energy Efficiency Programs”. Several of them have fulfilled this obligation by subsidizing the installation of photovoltaic on-grid systems to customers.
In my case, the system cost R $ 21.500,92 and the grant was R $ 15.926,61 (74%), so that accurate paid R $ 5.574,31 for everything. Payment was in cash, It hurts in the pocket but is paying off. With the economy I've been having on energy bill, the system will be paid in less than 2 years.
The offer was made by the concessionaire, by email, in April last year. There were five options available:
|System option||Recommended for consumption between¹||Estimated monthly savings||Original Value||Project discount||Amount to be paid by the consumer²||Return on investment (years)||Useful life of the system (years)|
|1||300-400 kWh / month||R$ 229,84||R$ 15.253,52||R$ 11.298,90||R$ 3.954,62||1,4||25|
|2||400-500 kWh / month||R$ 275,81||R$ 17.146,97||R$ 12.701,46||R$ 4.445,51||1,3||25|
|3||500-600 kWh / month||R$ 321,78||R$ 21.500,92||R$ 15.926,61||R$ 5.574,31||1,4||25|
|4||600-700 kWh / month||R$ 413,71||R$ 25.054,57||R$ 18.558,94||R$ 6.495,63||1,3||25|
|5||>700 kWh / month||R$ 551,62||R$ 33.750,26||R$ 25.000,19||R$ 8.750,07||1,3||25|
I became interested in, ask for more information and asked for me to send a signed letter scanned, with the system option. Opted for the system 3. Later they asked the same letter, but for post office. In November the company that made the installation checking the technical feasibility. In the same month made the payment and the invoice was generated. The installation took place in early December, by third party, but only at the end of December is that the company made the switch of the meter and I could finally use the system.
The project in question was made for only 100 customers in two cities and must be completed. I can't tell you how they picked me, Since I've never sought anybody regarding this. I know several dealers have done this type of project and some have accepted projects that are sent by third parties. Anyway, the grants have served a small number of residences.
Note that my consumption actually fits between 400 and 500 kWh / month, then I could have opted for the 2. I preferred to spend a little more and choose System 3 to have some slack, for if needed expand the system later I would have the subsidy. If I had opted for the system 2, the system would pay for itself in even less time, inside of 1,3 years provided by the concessionaire.
You Can Clear the Energy Account?
Short answer: Not! Can not zero the energy bill, generating even consume more power than. The reasons are basically three:
(1) We need to consume a minimum of 50 kWh / month dealership
Even generating more energy than consumption, I still need to consume 50 kWh per month the concessionaire. For example, let's say in a given month I have begotten 300 kWh and consumption 300 kWh. Theoretically my account zeraria. But in practice what happens is that I'll have to pay for 50 kWh to the dealership, using only 250 kWh of whom I have begotten. The other 50 kWh generated will be as credit for(s) next(s) months.
About the 50 kWh incidem ICMS, FLAT e BOUNDARIES. The total is about R$ 35 the current rate. That goes for months that no additional yellow or red flag, that damn PT heritage. In the months that have additional, We also have to pay it on the R$ 35.
I'm not saying this to be unfair, We are using the CTM system for “Save” our surplus and use later. Without the concessionaire would need a battery bank, and the cost would certainly be much higher than the 50 kWh paid for the dealership.
(2) The Alckmin wants the GST on the use of the same system for energy offset
Here comes a nice slutty. I don't know if occurs in all States, but at least here in Sao Paulo the Government won't give up charge GST on the use of the system, even if the concessionaire does not cover so.
For example, in my February account, consume 274 kWh and injected 224 kWh. Actually injected more, but the rest was credit, Remember that 50 kWh (274 – 224 = 50) I need to pay.
The energy is divided into two: YOU and TUSD. The first is the rate of energy (YOU) and the second is the use of the system (TUSD). When we consume, These rates are charged, but when injected they are credited. The rates of GST are also debited and credited to YOU, but to the TUSD they are only debited. In the account they are appearing credited, but it's a system error of the concessionaire. They credit in a month but range again next month. See the R$ 17,37 ICMS on the TUSD that have been debited and credited to the account appear in February charged again in March as account “COML. ICMS CHARGED”.
The value tends to vary depending on the network energy consumption. In March I consume less network and therefore the ICMS plywood TUSD will be $ 14,92.
Anyway it seems to me a hell of a slutty, and was not informed me before I purchase the system. They said I would pay only the minimum of $ 35,00. In practice, with the energy ICMS injected this amount will have to jump to R $ 50 a R$ 55, depending on consumption.
The only way to reduce some of this ICMS is trying to focus the use of energy during the day, when it is possible. For example, leaving to use the washing machine during the day, we will be drawing power directly from our system. If we fail to use the machine at night, we are injecting energy during the day and then evening wear, and so paying the ICMS for using the system.
(3) Public lighting collection to the City
With a change in legislation, local governments became responsible for public lighting. Some municipalities have absorbed this cost with the taxes that already collect. In other the mayor and councilors has no regard whatsoever for their constituents and played more this burden to taxpayers.
The collection is usually done along with the electric bill. The legality of this joint collection is being questioned in court. But for now she's still being charged. With or without grid connection systems we continue paying for her.
Ultimately, those are the three collections (that can be two or just one depending on the city and State where is made the installation) I do not allow my energy bill is zero.
My generation, My consumption and my credits
As I had already reported, my energy bills were in the range of R$ 350 each in the last three months before the installation of the system. Before then they fluctuated around the R$ 300. In terms of kWh, that was my last us consumption 13 months before the system installation:
The increased consumption in the period was in October 2017, with 465 kWh. Considering that 50 kWh need to be paid to the concessionaire, I need to generate on average 415 kWh per month to pay as little as possible.
My system generated 488,4 kWh in January, 476,3 kWh in February and has already generated 454,2 kWh in March, not over yet. Thus I come accumulating credits. Between January and February were 244 kWh accumulated credit.
I do not know yet how will the generation of energy in the months when the days are shorter, as June and July. If the generation is low, these credits will be used.
I was probably quite conservative when choosing the system, for me now seems quite likely that I did not go use those credits. Indeed, when I considered the accounts that need to generate the same as consumed to pay as little as possible, I did not consider that 50 kWh would have to be paid anyway and, therefore, the aim should be to generate 50 kWh less than the consumption.
For those who have more than one property with account in your name, a property the credits can be used to shoot down another property account, even if the other property does not have a micro system. It is not my case, but this is something quite convenient.
The credits generated can be used up to 5 years after their generation. So I'm not in such a hurry to decide what to do with them. It may be that even 2022 my consumption increase.
Em último caso eu vou acabar usando essa energia excedente para gerar criptomoedas 😛 . Só não faço isso hoje porque com minha GTX 760 eu provavelmente não geraria nem o suficiente para cobrir o desgaste adicional dos demais componentes.
Confesso que fiquei com um pé atrás quando a oferta me foi oferecida. It seemed too good to be true. Mas pesquisei e encontrei as resoluções da ANEEL. Depois enchi o pessoal da concessionária de perguntas, pedi as especificações dos equipamentos, pedi o contrato, ultimately, enchi o saco até demais. Por fim, confiei também por ser algo da própria concessionária, e não de alguma empresa aventureira, que poderia sumir do dia para a noite.
Com pouco menos que 3 months of use of the On-Grid Photovoltaic System used for Microgeneration of energy, ainda não posso dizer que já recuperei meu investimento, mas se tudo correr bem, I can do it before the end of 2019, and thereafter I will be saving at least a R $ 250 per month in electric bill. It is an excellent investment. There is no risk-free investment that I would have the same return for the invested amount.
Eventually the system may need some maintenance. This is something that needs to be considered, but I do not think the cost of this will be greater than the energy savings. A few years ago it happened in the area a hailstorm case with such large stones that damaged many roofs and vehicles. Solar panels were also damaged on that occasion, so I tried to make a home insurance that covers solar panels to ensure.
Furthermore, there is also the property valuation. Contract I can not sell the system separately, but I can sell it along with the property if I ever decide to sell it.
I have not changed my habits and still avoid leaving lights and other waste from day to day. But at least now I've let my electronics in stand by without guilt. If you want to invest in more air conditioning, I'm off power to it and I can use it also blameless.
I conclude by saying that my recommendation to the On-Grid Photovoltaic System used for Microgeneration of energy It is very positive. I know that without the subsidy system is less attractive and I do not know if I would invest in that case. Mas meu objetivo aqui era esclarecer como o sistema funciona e dar o meu ponto de vista de usuário, sem todo o viés de “é só vantagens” que as empresas que oferecem esses sistemas mostram. Espero ter cumprido esse papel e deixe seu comentário se tiver dúvidas ou quiser completar o artigo com mais algum ponto que não abordei.
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Update (01/06/2018): Mais uma vez a concessionária, Electric, mudou as regras no meio do jogo. Now 50 kWh que são cobrados mensalmente não podem ser consumidos. Give way, se eu consumir 300 kWh e gerar 250 kWh, terei de pagar 100 kWh, sendo os 50 kWh obrigatórios e mais os 50 kWh que consumi a mais do que gerei. Já questionei-os sobre isso há duas semanas, but still got no answer.
Update (18/05/2019): Nos últimos meses, again, the utility has changed the rules of the game. Now 50 kWh continue to be billed monthly, but the extra consumption (beyond the energy generated) within these 50 kWh is not discounted from the credits. The extra generation (plus the energy consumed) normally accumulates, but not counting the 50 kWh pagos. Furthermore, ICMS de 25% referring to TUSD rate (use of the system) It remains always charged, because this can not be compensated.
- consume 300 kWh and have begotten 280 kWh, I will pay for 50 kWh, and nothing will be deducted from my credit.
- consume 300 kWh and have begotten 230 kWh, I will pay for 50 kWh e 20 kWh will be deducted from my credit.
- consume 300 kWh and have begotten 320 kWh, I will pay for 50 kWh e 20 kWh will be added to my credit.
In practice, the 50 kWh are required to pay, and can be used to cover the difference between generated and consumed, but if the difference is below the 50 kWh, you can not accumulate surplus. Only accumulates when the generation is effectively higher than consumption. Likewise, only use credits to pay the difference between consumption and generation that exceeds 50 kWh.