Solar Energy for Beginners

Solar Energy is the nearest one, in our own home, but we rarely consider it. It’s true that, in the past, solar energy use to be not really profitable, but this is something every time less true. In this post we will demonstrate nowadays is really simple and profitable.

First step is to check what we could get in the place where we live.

SolarGIS-Solar-map-World-map-en

SolarGIS offer more detailed maps, but let’s see an intermediate area where we could get 5 KWh daily and 1.800 KWh per year. Assuming a KWh cost of 0,11 € we could save 1.800 x 0,11 = 198 €. Almost 200 € per year and per square meter.  Promising.

Once checked business is possible we will look for available space in our home. Usual (and most profitable) solar panels are 1 x 2 square meter ones providing around 250 W power. They are provided with different voltages but we recommend 24 volts ones. 12 V panels need high current and 48 V panels could reach 80 volts making them so dangerous. Price for recommended panels use to be around 200 € without installation.

panel_solar_atersa_300w_preciopanel-solar-axitec-300w-24v-policristalino

As an example we could consider we have 8 square meters available. Solar panels price will be 800 € producing 1.600 € savings per year in the conditions mentioned above. Only 6 months savings cover panels price. It looks really interesting but we need more additional investment not really cheap. We have already our solar panels but we have to install them.

If we have a plane and accessible area we could install solar panels by ourselves but, in a roof with a difficult access it is better professional people to take care of installation. We could consider panel orientation bellow but our recommendation is doing installation as simple as possible. It’s better to install an additional solar panel than doing a complex installation. Solar panels are not the highest cost in a solar energy installation.

Estructura-Paneles-Solares-Cubierta-Plana-Suelo-1-ud-CH915

Panel orientation use to be fixed. Automatic orientation mechanism is the ideal solution but it’s expensive and complex. Consider moving a 8 square meters surface following the sun. Usual panel orientation is south but, in some cases, it’s oriented to south-west or even west. The reason is people use to work in the morning and afternoon and there is few energy consumption at this time. Oriented to west optimize performance when energy consumption is high.

Recommended angle or tilt is the same as the latitude where we live. If we are leaving in a latitude 23º area we have to install panels with 23º tilt. There are a lot of articles in internet with recommendations about correction factor to be applied to the previous rule. This correction factor use to be different for winter or summer forcing us to modify tilt during the year.  As mentioned above the best solution is the simplest one.

Ok, we have the energy from the sun, but we have to bring it to our home. Using recommended solar panels (250 W and 24 V) every one will produce around 10 A current. We could buy cables in any electric material shop requesting any 10 A cable, AC or DC cables are valid. Anyway, in case of a long distance, it is good to select a cable with more capacity in order to reduce losses. Our recommendation is every cable has its own cable. In case of problems it’s easy to disconnect a panel with problems disconnecting the corresponding cable.

Once the energy is in our home the most easy and efficient way is using an inverter. Inverter convert 24 V DC power to 120 V or 220 V AC power same as our home electricity installation. Home electricity network schema is shown below:

 Home Network SchemaInverter works in parallel with electricity coming from electricity network reducing consumption. There are two important points to consider when selecting an inverter for a proper functionality.

  • AC electricity produced by inverter should be pure sinusoidal wave. Bad quality of the wave generated will affect other end customers. Smartmeters detect a bad quality wave informing electricity distribution company.
  • Zero injection. If our electricity consumption is lower than the electricity generated by solar panels the different is sent to the electricity network. Normal meters charge this electricity same as consumed one. Newer Smartmeters detect the direction is the opposite and inform electricity distribution company. Probably we will receive a complaint. Only in few countries we will receive a compensation for the electricity supplied to the network.

In our example we have bought 4 panels with 25o W each one. We look for a 24 V and 1000 W inverter. It’s recommended to buy a more powerful one as double power means a few additional cost. 2.000 W inverter will allow to install more solar panels in the future. Price use to be around 1.000 €. There are some models named “hybrid” providing an additional connection for batteries. It’s recommended to select a good one in order to use properly our solar system and avoid problems with our electricity distribution company.

Understanding how inverter works is important for a good performance. Solar energy, without batteries, is not stored anyplace. In case of low consumption zero injection detector informs inverter and it increase working voltage forcing solar panels to produce less electricity and we are not fully taking advantage of our solar system.

First option is adapting our consumption to solar panel production. Some inverters inform about available power and used power in a front display. Home appliances like washer machine or dishwasher could be used in the time more solar power is available.

Second option are hybrid inverters and batteries. With this solution we don’t have to take care and solar panels production will be fully used. Inconvenience is a higher investment as batteries are expensive elements.

Our recommendation is using a hybrid inverter, a bit more expensive than normal ones, and leave batteries for a second phase. Once we have our solar system under control we could decide if battery investment is worth.

As summary solar energy is profitable and necessary investment could be covered in two or three years. From this time all is profit. I hope this article useful and, in case of any doubt, don’t hesitate to write it in comment box.

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