[Skip to Content]

Mk2 DIY Solar Panels

Published on Saturday 09 May 2009
Categories: Solar Power |

After purchasing further solar cells from the USA via ebay, We are building four new weather proof outdoor solar panels which should supply around 320w which should be enough energy to run the household lighting circuit and all the low power appliances in the house including the computer networks, router and phone and small appliance chargers using.

The panel built last year using foamx plastic for the backing has twisted over the winter and didn't respond well to sunlight over the year so the new panels will be built from 12mm marine ply wood with 2mm glass fronts and with 20mm aluminum corner edging. The new panels will be fixed to two 4.8m long aluminum bars which will be fixed between each side of the roof on the chimneys.

Started work today building the wooden backing boxes for the panels which are 575mm x 1020mm x 16mm. Along the edge of the 12mm ply wood, we attached strips of 4mm thick pine to hold the glass above the panels and across the main panel area attached strips of 2mm wide by 4mm high wood to act as spacers between the cells and also to support the glass.

The photo below shows the finished board ready to be primed and painted.

single solar cell

The photo below shows the four panels ready to be primed and painted.

single solar cell

Two coats today of Dulux Trade Weathershield Preservative Basecoat to seal the wood, this needs 48 hours to dry and then the panels will be painted with exterior gloss and the glass ordered.

The photo below shows the panels after bring primed with two coats of wood Dulux Trade Weathershield Preservative Basecoat. (poor quality as it was taken with my iphone)

Solar panels being painted

Using 35mm square aluminum bar, we machined a slot into the bar and cut it into 30mm wide brackets which where drilled and tapped to take M5 bolts. Four of these brackets will be bolted to the panel base boards and this will allow the easy fitting and removal of the panels to the 25mm square tube which will be fitted across the roof.

The flat aluminum brackets to bolt to the chimneys on both sides of the roof are also finished and have been painted. They will be fixed to the chimneys when the weather permits.

The photo below shows the aluminum mounting brackets after machining.

single solar cell

The wooden panels have now had 2 coats of exterior gloss paint on both sides and the base will have one final coat of paint before the brackets are fitted.

The photo below shows the finished boards being painted. (poor quality as it was taken with my phone)

single solar cell

Using 6mm thick flat aluminum bar, we made four brackets which were attached to the chimneys either side of the house and between these, two lengths of 25mm x 4.2m square aluminum bar were fitted to act as supports for the solar panels.

The photo below shows the brackets fitted to the western end of the house.

brackets

 The photo below shows the brackets fitted to the eastern end of the house.

brackets

The photo below shows the pair of mounting bars fitted between the sides of the roof.

brackets

The bars are held approx 15mm off the slates to allow the solar panel brackets to slot into place and allow rain water to flow under the panels.

Charging System Upgrades

The existing charging system used a single battery and this was connected via the charge converter to the inverter and a 12v relay which switched the mains supply between the solar inverter power and normal mains electricity.

The disadvantage which this system was a 1-2 second delay between the inverter shutting down and the 12v relay switching over to mains electricity which resulted in the lights going off for a short period when the battery was low as everything switched over.

The upgraded charging and inverter circuit uses a delay timer which keeps power to the inverter for an additional 2 seconds whilst the switch over relay changes to mains electricity from the inverters output. This virtually eliminates the loss of power to the lighting whilst still keeping the inverter running during the switch over.

The delay system uses a 741 comparer chip setup as a Schmitt trigger with a simple power off delay using a capacitor and the output for the inverter is switched to battery ground (0v) using a pair of 60Amp switching Mosfets.

Other Upgrades

In order to allow the upgrade to 2 or more batteries we added two more large connection blocks (bottom center in the image) and also a separately fused (5A) low current feed for supplying LED lighting and 12V appliances.

We also added two battery isolation switches which allow the charge controller to be isolated from the batteries and the solar cells. The instructions for the charge converter say that you must disconnect solar power before the batteries so this was the reason for adding two high power switches.

The photo below shows the charging and inverter system, click for a larger image.

charging system

Soldering Cells

After purchasing a flux pen from Maplin, we started the long job of tinning all the cells, front and back and the fitting the tabbing wire between the cells to join 36 together for each solar panel.

The photo below shows the rolls of tabbing wire, the flux pen and a pack of 50 cells

solar tabbing wire

The tabbing wire was cut into short strips to join the cells.

solar tabbing wire

The photo below shows the first siz cells joined.

solar tabbing wire

The photo below shows the first complete row in place in the panel.

solar tabbing wire

One row complete of six cells complete, only 144 cells to do with 2 tab wires on each to go.

Putting it all together

Built the first of four panels today and got it installed on the roof. I am still waiting for the 12v 15amp cable roll for the other three panels, which I ordered over a week ago and the supplier isn't answering emails so it looks like I may have lost my money and will have to find it elsewhere.

The photo below shows the thicker tabbing wire used to join the rows of cells

tabbing wire used to join the rows of cells

The glass was fitted to the panel using sealant and the alloy corners fitted to each side.

glass was fitted to the panel

The first panel completed and ready for fitting on roof.

first panel completed

The photo below shows the front of the house with the first of four panels fitted on the left.

front of the house with the first of four panels fitted on the left

Permalink


0 Comments



Leave a comment