Building a solar panel using polycarbonate base instead of glass

Cell acquired on Ebay ; 3.5W and 14.1% efficiency 100 ud. € 105 from Solar_rex

UPDATE: DON'T do this, it doesn't work more than a few months, due to the different thermal-expansion of the policarbonate film against the cells, it brokes the cells apart.

Lately he has given me to go against the government moves about , and I'll build a couple of experimental solar panels that give me hope 340 Wp. This ideal situation is never going to give, so at least I hope that normally produce about 150W with good sun, that's what I always spend a minimum and thus eliminating the cost of an appliance like a refrigerator; I estimate a saving of about 5 € per month. It's not much, but the cost of all materials as amortizaré in about 6 years, and if all goes well, will produce about 20 years.

Contrary to what you think our government (as usual), photovoltaic panels HOUSING (I am against them on land until they are more efficient than trees SETTING obtaining energy and CO2) only have advantages for that install and rest of society ; produce more than they consume and generate when it is consumed, stabilizing the system and reducing energy losses. And that that that install "take advantage of the system by eating at other times" is very subjective, and only affect the hours from 17 to 23 hours a day, and that hour the rally can be supplemented by indigenous energy Green generation from solar, very economical and available at those times hubs.

Although I'm going to do because I love the "do it yourself" and has always done me a huge illusion build me one,  usually fabricarte your own panels is not profitable , because, apart from the time required for all the preparations, they can stay bad and quickly spoil if they are not adequately insulated from moisture; no finished panels that only cost 50% more than it would cost only loose materials. Using polycarbonate base But as we are, we will break the deck and risk using insurance, economic and resistant polycarbonate instead of the usual low-iron tempered glass .

Advantages of using polycarbonate front glass photovoltaic panels :

• Economy; It is up to 4 times cheaper.
• Resistance: It is virtually unbreakable; endures all hail; 200 times more resistant than glass.
• Lightweight: Weighs approx. 3 times less than the glass.
• Security: A traditional glass module released by wind or poor subject represents a great danger to people and materials by weight and features.
• Utility: flexible, easy to work, can be drilled and cut easily.

Disadvantages of PC versus safety glass:

• Dilates 3 times more than the glass (coef. Of 65x10E-6 versus 20x10E-6 glass), so you need to choose a fastening material PC cells to absorb these thermo-mechanical stresses.
• Has less transparency; while the crystal can reach 98%, the PC is 90% (without considering that usually come treaties to reflect UV rays and longer life).
• Whitens time; 20 years transparency is reduced by 5% in those treated against UVA as Lexan that I use.

Less transparent it is not greater problem; to receive less sunlight silicon cells will produce somewhat less daily life but also extend proportionately as they can only produce a certain amount of energy before going to deteriorate more and more (as mentioned, about 25 years).

By having silicon cells PC and the motion control different thermal expansion coefficients, the choice of a material mooring cells while protecting them and to stretch along with the PC base is critical to ensure the durability of the panel and the cells. Let's see how we will dilate panels have prepared .

The expansion coefficient of polycarbonate is about 67 x 10E-6 = 0.00067. To calculate what we will dilate we must use the following formula:

Thermal deformation ( d ) depends on the coefficient of thermal expansion ( a ), element length (L) and the temperature change (DT) and can be calculated as:

d  =  a  L  D T

Therefore, the plate that will use the maximum variation that you will have are:

0.000067 * 1500 mm long * dif. temperature (about -15 to 70 ° C;. 60) =  8.5 mm.approx.

70 is in the worst case, when the summer sun tightening, as the cells become very hot and much of the heat transferred to polycarbonate. Evitarems clamps fixed everything, and if we have to drill to fix, we will have sufficient clearance for expansion; just make holes with a torn 1cm holding screw and washer grandesy rubber without tightening completely, so that the panel is subject but can "float" on the grip. 
If we do well and put too many screws while the plastic shrink and expand, it will eventually break . To pierce the solid plate drill we can use wood or iron, ensuring that the material does not get too hot while drilling (can use a little water for cooling).

Indications drilling in plaque

Using neutral silicone sealant as
the other hand, considering this, we must analyze the adhesive used to fix the cells, the first thing that came to mind was the epoxy resin and neutral silicone; speaking with a professional bouquetI opted for the neutral silicone resistance to UV light, durability, flexibility, price and especially adherence to PC . If we choose to fix the cells using neutral silicone transparent only from the reverse side, which has an excellent grip on the polycarbonate and allows the passage of light between cells, keep in mind that the cells, dilation effect PC, they will rub therewith to fray a little while emborronándolo over the years; reducing its efficiency, we must also assess put between the cell and polycarbonate, as thin as possible, for the expansion of polycarbonate, to get cooler than the cell, the end will be close to it; and 5 mm. to dilate up to that extent the PC compensate with 3 mm. maximum of each of the cell expansion; 2 mm. difference that silicone can stand perfectly.

Finally remains to determine whether the silicone chemistry we choose attacks the material of the photovoltaic cell . The information I have found is that even can replace the EVA as a sealant most effective and easy to work, such as acetone silicone Neutra, that being neutral, if we let it dry well does not have to give any problem, but time will tell as silicone used is relatively new. The transparent neutral silicone has the following advantages over other materials:

• Excellent adhesion to PC.
• Stable and resistant to UV rays to the weather.
• Wide range of operating temperatures; holds no muss from -50 to 250 ° C.
• If it is colorless, has excellent light transmission.
• Unsurpassed flexibility, up to 400% elongation.
• Repairable and easy to use.
• Economic.

To mount the first cells have to stiffen the polycarbonate , for although the cells have a bit of stretch (very little, are extremely fragile), we must prevent us twice to go to place.
To do this I will prepare in advance for the support, and I will tie him to place the cells then glued with neutral silicone colorless transparent. Os I will comment about my progress, wish me luck;).Be happy!

Sources: Calculation of deformation temperature changes of the material Use of PC analysis on PV solar cells ( mirror ) Use of silicone as PV Cell encapsulation efficiency comparative study using EVA or silicon photovoltaic (English) ( mirror ) Advantages of encapsulating gel Silicone versus EVA Polycarbonate: Their advantages over glass

Building your own High Quality CREE LED lamp with 700 lumens and spending only 6W

Mounted lamp with recycled parts

In this post we will see how to build a LED lamp for your house with 700 lumens with only 6W power consumption using 3 chips CREE XML T6  fed pure white 166 mA each (6W / 12V = 0,166A) a controller 220V with 6W 12V output power, and something like this cap , but I used a recycled sink another LED lamp 7W (thermally conductive plastic) and a fine of an old E14 energy saving lamp. Total Cost: € 18

The CREE LED chips are expensive but give much light per watt, high quality and durable, enduring the worst working conditions.

By making LEDs work well below their rated power (only 25% according to its spec sheet ) get more light per watt, while also reducing its temperature and lengthen your life until after 30,000 hours . A bulb in which the driver will break down before (10,000 hours estimated by its electrolytic capacitor life) before the LED. Furthermore the CRI (color accuracy) increases the lower the current.

Rehabilitating one Metabo screwdriver with a Li-ion 4400 mAh 12.6V

Metabo BZ 12 SP with DIY Li-Ion Battery

As a gift, I was given an old screwdriver that was going to go to waste. It used the old Ni-MH battery technology or Ni-CD, and you know me ... I love those tools that works wirelessly, so I started to build for it a more economical, durable and powerful li-ion battery than the original, as there are no li-ion batteries for this screwdriver.

Note : Adapting these instructions you will be able to build batteries for any wireless device that you have at home and that, for its price or quality of their batteries, you are considering to throw away.

This requires using Li-ion batteries that allow discharge at 2C at least, or they could be damaged quickly. Lipo could be used but these have half life than other liIon chemistries. The Li-Mn (manganese) allow faster discharging without damage, but are quite expensive, and LiFePo, A123 manufacturer would be ideal, but pricy too.

I found a middle ground in Lico of  Boston Power-shaped like two 18650 united , but actually is a single battery, ovalish format, making better use of the space, and with very good capacity for cases where two batteries are used in parallel (such as laptop batteries), and they have a very good chemistry that is not damaged by 8Ah instantaneous demands such as a screwdriver, retaining its capacity better than others between uses:

See below Load controller chip

The humidity at home: Origins and possible solutions

Typical grid to beautify vents

When moisture appears in our house, the most important thing is to find out its origin , since it depends on the applied correctly and lasting solution, avoiding wasted expenditure of time, energy and money.

Moisture not only spoils the walls and all kinds of organic material (mold on leather, wood, etc), but their lack of treatment can be a source of health problems ;fungi, breathing problems (asthma, allergy), etc. While a definitive solution can not locate, we try to keep it in a healthy range (45 to 65% saturation) with a dehumidifier for example.

Designing a wood stove: simple, convenient and efficient combustion: Understanding the process of combustion of wood (3)

Picture: Hergóm 

To find an optimal design in an oven, we must analyze and understand the process of combustion of wood; variables involved, phases, each phase processes, better combustion conditions, etc., a theme to spare studied by engineers and encompasses knowledge of different subjects: thermodynamics, fluid dynamics, chemical dynamics, mechanical properties and thermal properties of various materials etc.

When designing an effective, safe and easy to build homemade stove, we find the following dilemma:

As the efficiency of the stove grows, so the complexity of it.

However we must look for a committed performance and simplicity and ease of construction that fits the overall needs in burning wood design , and our goal should be that, later to be implemented improvements (also easy to implement if possible ) that can increase performance.

Wood stoves with secondary combustion: Less smoke and more performance

In this blog we have been analyzing the benefits of using biomass to heat our home for profitability and ecology.

In this post I will discuss something even more beneficial for our pocket and nature: The technology of double combustion wood stoves. With this system, lacking the vast majority of wood stoves, get even greater performance avoiding much maintenance to avoid the generation of smoke, which the outlet tubes accumulate less soot and tar with use, produced by imperfect combustion of the gases expelled by the timber to catch high temperatures.

Soot particles are carbon that failed to burn and did not pass gas as CO and CO2.

Philips vs Braun Shavers, what is technically better?

As you can see in the video, while most Braun afeitaduras use their own proprietary system, in which the blades cut hair using a reciprocating, and is actually the floating plate moving under a thin steel sheets the which makes the cut, in Philips shavers have 2 or 3 discs that cut the hairs that pass between the slots, cutting more effectively and accurately.

The SmartTouch XL; a marvel of Philips

Repairing an LCD screen: Replacing blown capacitors

The capacitors are famous for electrolytic fail when subjected to long time of use, temperature and stress, swelling and bursting the top cover where release of the electrolyte liquid inside. Many basis of old computers that had this type of capacitor plates ended up failing after 2 years, and now they are substituted for polymer electrolytic capacitors aluminum, stronger and more durable.

IMPORTANT : Before you throw a screen away because you think beyond repair, ask before budget in an electronic workshop , it may be a small thing (every day are cheaper and sometimes costs more to repair, but still not worth more than a new repair, convenient repair, you are recycling, less waste and investing in local labor).

In this case I was left a screen which two seconds to light the lamps emitting a like a very low "zzzzz" buzzing sound turned off. The sound was probably the vibration of capacitors stage transformation frequency of 50 Hz which is the AC, that being in poor condition that sound emitted.

How to heat a home with an open fireplace: Adding a cupper coil, by Rafa

Fireplace coil made of copper by Rafael, with added doors

The people are so rigged. Rafa, a Seville plumber of 52 years, residing in Gerona has been kind enough to share with us their system , very similar to mine , which  for heating radiators leverages the built-in fireplace (yes, those that turn you on ahead and I grow cold by behind), achieving a more than worthy result to save wood and heat the house. 
He was not aware of these pots (used in villages of the Basque Country for decades), and their parents save money and gave googled my page, went looking for and found Lacunza, in whose  assembly schemes relied for connecting pumps, thermostats , etc., which sells kits pumps and thermostats ready for its chimneys, and the coil was based on the they have for sale Fireplaces Sierra , but made ​​with 15 mts. welded copper tin / silver . Detail thermometer, thermostat at 45 ° C to activate pumps and sensor of the safety valve 90 (not visible in the picture, touching the tube) which triggers a valve that ejects the last water this temperature outside and in turn enter cold water from a faucet automatic filling (in another photo) set to 1.5 bar:

Detail shot regulating door, right thermostat, thermometer and safety valve sensor

The best choice for heating your home (updated 2014)

How do I heat my house cheaply and with greater comfort? This same question I became in the summer of 2006. And now I discuss in this article that will update as circumstances change.

Before heating, is 10 times cheaper and more effective to isolate; in this post or  this one's more information on this topic.

Having analyzed and changed the heating my house I have acquired some knowledge that I share with my readers, since heat your home is a major expense that if we do not choose it may prevent us to make ends meet during the cold winter months ; - ). Nor find myself in possession of absolute truth, so take my advice and reasons for yourself.