Solar Power Station

In a similar vein to a number of projects on Instructables I wanted to create a solar powered charging system for the multitude of battery operated gizmos that own. In addition, an aim was to de-clutter the need for multiple wall warts and associated charging leads and accessories.

The outcome is a centrally located station which some effort has been made to make it look like a reasonable piece of furniture in keeping with its location in the centre of the house.

Main Requirements

Recharge Laptops

Recharge Phones (micro USB)

Recharge any USB device with USB charging capability eg ipad/ipod

Large Battery for overnight charging (when sun not shining!)

Easy to use and aesthetically pleasing to look at.

This build was not a cheap one but many of the components I already had or had experimented with on previous projects. This essentially bring them all together in a neat package.

Whilst all the circuits you need to wire are 12VDC and (as such are catagorised as extra low voltage) you are ok to work on a project like this with no electrical license. However I would point out the following notes:

1) A Lead acid battery has a lot of stored energy that can cause problems if you short out the +Positive (Red) and -Negative(Black) terminals. Be very careful when connecting terminals to the battery. It is very easy to accidentally short out the terminals - I know I did it many years ago when working on a car - sudden blue flash and melted battery post Doh!

2) Batteries undergoing charging/discharging can get warm/hot - ensure your project has enough "breathing" space to compensation for this. In this case, given that the maximum output of the Solar Charger is 10Amps and the battery can handle 30Amps initial charge it is unlikely any appreciable heat generation will occur.

3) This project uses a sealed GEL Lead Acid Battery which under normal circumstances should remain sealed. If you use a flooded type battery beware that it produces hydrogen gas during the charging cycle. Ensure that your project is not located in an unventilated area.

I have tried to make this project achievable by the typical DIY person. The higher your skills and patience are the better the outcome will be. Most of the project is to wire together bought components. This is fairly simple DC circuit wiring. The woodworking skills for the box are straight forward and don't require exotic tools to create.

Tools

For the Box:

Saw - handsaw will do

Saw - Jigsaw (for square cut outs in box). A chisel might be an alternative here, but will take a while longer

Drill and set of drill bits

Screwdrivers

Rulers and pencil for marking out

Paint roller and brush

For the Wiring:

Soldering Iron - only a couple of joints required.

Wire cutter/stripper

Crimper and spade terminals for wire terminals

Multimeter

Terminal screwdriver

Hammer - for cable clips

I decided to go for a 12VDC 100Ah Lead Acid GEL Battery which is specifically constructed with solar use in mind. This is the single most expensive item and will give 3-4 days of usage if we have a run of cloudy days. Here in Sydney Australia we are blessed with good solar insolation. Your choice of battery and solar panel needs to be matched with your usage which is not difficult to calculate but will be different for each person.

On a more practical note this battery is very heavy and I just about gave myself a hernia moving it about, Anything bigger and it starts to become a 2 man effort.

http://www.jaycar.com.au/productView.asp?ID=SB1695

the spec sheet is here

http://www.jaycar.com.au/products_uploaded/SB1695_...

This panel was a cast off from a previous project and is plenty big enough to keep the system ticking over nicely. It was bought a few years ago and I think its about ~130-150Watts at full tilt. The unit is mounted on a single story roof facing north (best direction for southern hemisphere). I've used solar cable to wire to a recessed wall plate

I have used a EP Solar charger and display meter. The package was purchased on E-bay but the website is here:

http://www.epsolarpv.com/en/index.php/Product/pro_...

I choose this controller because:

1) It is a MPPT type to maximise the charge

2) It has a load switching feature which can switch on at dusk or before dawn - I've used this to power a small strip of LED's

3) The charger has an associated display meter showing a number of key parameters.

However there are other controllers with similar specs - so you can make an alternative choice.

Here are 2 small power supplies which are suitable for setting up for USB charging.

One is a switch mode power supply kit from Jaycar. The other is a LM317 based on bough off Ebay. Here are the links.

http://www.jaycar.com.au/productView.asp?ID=KC5508

http://www.ebay.com.au/itm/LM317-DC-AC-4V-30V-Out-...

Both do the job but the Jaycar version is the 'modern way' while the LM317 harks back to the original design which was done in the '70's. Again I had these lying around so decided to use them both. Each power supply could simultaneously charge several devices (@100ma each).

Notes for interest: The switch mode type power supply is great where efficiency and cheaper components are the key however a linear regulator is better where you need very low noise or ripple (for EMI sensitive devices). Both are fine for the job here.

This is a variable voltage power supply for laptops. I bought it a while ago and the closest I can find on the Jaycar website is:

http://www.jaycar.com.au/productView.asp?ID=MP3324

It comes with a range of plugs and should be suitable for most laptops. There are other options out there on the web. Mine is set up for 20VDC and fitted with a plug for my aging ThinkPad.

After construction note: This item seems to get quite warm in use (~40-45DegC) - give it some breathing room!

Yet another part that was bought some time ago and has been previously experimented with. At 300W its not big enough to run a many household appliances but it is good enough to run smaller items such as a TV. Here in Sydney we experience a few power outages each year (due to thunderstorms hitting the overground powerlines). Having a small semi portable (the box has castors) 240V AC supply should be useful in these times. The only house in the street with lights still on!

Here is the link:

http://www.jaycar.com.au/productView.asp?ID=MI5104

NOTE: I have not earthed this inverter and so it should only be used with double insulated devices (devices with 2 pins on the plug).

The wall plates give a professional appearance and the 12VDC "Cigarette" power connector are shown in the photo above.

The 4 way plate is a std wall plate for keystone inserts, the inserts themselves are for the USB sockets (not shown on the photo) are these:

http://www.jaycar.com.au/productView.asp?ID=PS0773

The brush wall plates (2 required - one for back and one for the lid of the box):

http://www.jaycar.com.au/productView.asp?ID=PS0291

The 12VDC socket is:

http://www.jaycar.com.au/productView.asp?ID=PS2002

Fuse Box - please fuse all your circuits - a 12V battery can provide a real punch of current that can easily damage equipment.

http://www.jaycar.com.au/productView.asp?ID=SZ2002

In-line fuses - used to fuse the main battery to inverter lead and the battery to solar charger lines

http://www.jaycar.com.au/productView.asp?ID=SZ2042

http://www.jaycar.com.au/productView.asp?ID=SZ2040

There is no reason why I used different leads - its just what I had in the garage at the time.

White LED strip

I had a length left over from a 5M reel bought on E-Bay - it had a self adhesive backing.

Plastic Boxes for internal storage

These 2 boxes came from Howards Storage World - Cadi stackable organising basket large PLF024. www.hswgroup.com

Miscellaneous Parts

1) Wood Glue and Screws for Box

2) Wire Black and Red for DC circuits - I used 15A automotive except for the Battery to Inverter which I used the cable that came delivered with the Inverter (30Amp I think)

3) Spade terminals

4) Cable clips

5) USB cables - to be cut off and used inside the box

6) 25 x 25mm Aluminium Angle - for the basket shelf supports - this is a bit of an afterthought and if I made another box I'd just use wooden battens before painting

My apologies I did not take any photographs of the basic construction of the box. Hopefully the photographs are enough to guide you into constructing your box. To make the box construction easy I used pine boarding from my local hardware store (sold for shelving primarily) . I utilised the full 405mm width and therefore minimised the number of saw cuts I had to make.

http://www.bunnings.com.au/porta-pine-laminated-pa...

The basic dimensions are:

Nominal Dimensions (dimensions including castors skirting and lid) 740mm Wide 415mm Deep 395mm High

Do not use the nominal dimensions for construction they are only for information to assist you to see if it fits in where you propose to locate the Power Station.

Box Internal: 665mm long x 345mm wide 405mm high (width of the board)

Lid 735mm Long x 405mm Wide x19mm thick (thickness of pine board used)

The size of the box is dictated to a certain extent by the largest item contained within (ie the Battery in this case). If you decide to size you own box I urge you to ensure you have enough space - once you start assembling projects like this if you are tight for space it makes things quite frustrating and can make it hard to maintain or improve. In this case its good to "Go Large".

Pieces required to make the box:

Lid (1) 735mm x 405mm

Front and back (2) 700mm x 405mm

Sides (2) 345mm x 405mm

Base 700mm x 383mm (the base requires a cut along the long side of the board to reduce the 405 width to 383)

After cutting the parts were glued and screwed together. 3 screws down each corner. Leave the box overnight for the glue to cure fully

Castors

4 castors fitted to base - as an assembly the finished product is heavy. You will regret not fitting them if you decide to leave them out!

http://www.bunnings.com.au/ambassador-40mm-unhoode...

Hinges

Fit the hinges then remove the lid in preparation for painting and finishing

http://www.bunnings.com.au/zenith-50mm-brass-fixed...

Batten for battery

Add 3 short strips of wood at the left had side of the interior of the box. This is to ensure that the battery will have an air gap all around it. The batten is about 5mm thick.

Batten for LED Strip
Fitted a length of pine molding for the LED Strip

http://www.bunnings.com.au/porta-19-x19mm-3-0m-cle...

I decided to paint my box - I filled in the holes with woodwork filler then sanded down. I fitted the already primed skirting after sanding down.

Skirting
This finishes off the base of the box and makes the box look like a small storage or blanket box. I fitted the skirting using panel pins and wood glue. The Left hand side requires a cut in the skirting to accommodate the 240V inverter

http://www.bunnings.com.au/woodhouse-92-x-18mm-5-4...

I used a combined sealer, primer and undercoat. Only 1 coat required. The box is painted inside and outside.

I had some wall paint left over from an old decorating project. Slightly off white or should I say "Hog Bristle" as it said on the can.

2 coats required.

To improve the look of the finished Power Station, put a coat of paint on the brilliant white face plates. Simply rub the faceplate with some fine sandpaper to provide a key for the paint.

Note for future...

I have plans to add some finishing touches to the outside of the box. Watch this space - my artistic capabilities are very limited so if the idea doesn't look good it will get painted over!

Fit the battery into its location in the left hand side of the box. Boy is this sucker heavy!

Note the air gap all around the battery sides.

Attach the LED strip onto the batten. The LED's are facing upwards so that the light 'washes' the wall behind the power station. Insert a 2 wire cable through a small hole in the box. Solder off the +VE and -VE onto the LED strip. (The LED strip should show which is -VE and +VE).

Fit both the brush wall plate, the 4 way keystone wall plate and the 12VDC socket

The cutout in the right hand side end fits snugly around the end of the inverter. Slide the inverter into position then screw to the base. 2 screws at the back are enough.

Fit the 5VDC power supplies that will provide power to charge up all your USB devices. I used spare computer stand off's screwed directly to the base of the box.

Fit the charger to the back side of the inside of the Power Station box. I also terminated the LED strip at this stage. It connects to the load terminals on the right hand side of the solar charger.

Fit the fuse box in a convenient location. We will be fusing each of the 4 circuits individually.

1) For 5V Power supply 1

2) For 5V Power supply 2

3) For Laptop power supply

4) for 12VDC Socket

This cannot be fixed in position so I just placed cable clips on the input and output leads. The output lead will go through the brush wall plate on the power station lid.

Start wiring up the components.

For the main battery to Charger and Battery to Power supply I used inline fuses like this:

http://www.jaycar.com.au/productView.asp?ID=SZ2042

Use red for the positive and black for the negative. Keep the routing as tidy as you can and use cable clips to help in this regard.

Using around a meter of solar cable to wire from the recessed socket to the right hand terminals of the solar charger. Pass the cables through the brush wall plate in the rear of the box. The spare cable stores neatly underneath the box allowing the box to be placed about 50mm from the wall. The cables from the battery to the solar charger can be done now also. These terminate to the centre connections on the solar charger. Leave the fuse out of the circuit at this stage.

Temporarily (and one by one) add a fuse into the circuit and test and set the 5VDC for the USB chargers. There is a potentiometer on each circuit board to adjust the voltage. Remove the fuses and continue. This process should have been completed on the bench but it is a good idea to test again.

Also take the opportunity to test the laptop power supply the Cigarette12VDC socket and the 240V Inverter.

Make sure you get this step correct ie the polarity of the USB wires) - I do not want you to damage your phones/ipods etc!

Take a couple of unused USB cables (I'm sure you have some somewhere at home!) and cut the cable approx 150mm long.

Strip the outer cable back and expose the wires. Cut off the green and white - these are the data wires and are not required for charging. Terminate the red and black wires into corresponding terminals on the 5V power supplies. In my Power Station I wired one of the 5V supplies to a multi-headed lead I bought off e-bay and the other to 2 USB sockets on the back of the box. The multi-headed cable is connected to a USB extention cable (with a female type A USB socket on - see photo)

ebay link:

http://www.ebay.com.au/itm/Multi-10-1-USB-Charging...

I have left 2 of the USB's disconnected for the moment.

Further USB charging Notes: It is true that these days may devices use digital recognition to allow higher charging currents, however in this case the charging is essentially 'dumb' and each device should default to 100mA to your device. This means it may charge more slowly then when it is connected to its dedicated charger or a computer. I do not find this a problem however - its just good to be aware of it.

Seee the Wiki here for more information and your further education!

http://en.wikipedia.org/wiki/USB#Power

Fit the brush wall plate and the solar charger meter to the lid. Refit the lid using the hinges. Connect the meter to the charger with the supplied cable.

Towards the end of the assembly I decided to fit a couple of plastic trays. The idea is that you will have loads of USB leads, wall warts, instruction manuals - basically loads of paraphernalia that needs a home and a location you can go to without searching the whole house!

I fitted a couple of aluminum 25x25mm angle to the right hand side of the box. They are located 170mm down from the top of the box. This is to suit 2 of the plastic trays from Howard Storage World. - if you can not get these I'm sure you can find an alternative.

Reinstall the fuses one by one and check each is operating as you would expect.

I used a 10A fuse for the solar charger and 30A for the 240V inverter

I used 5A for each of the 5V DC power supplies and 10A for the Cigarette 12VDC socket and the Laptop Charger

I hope you enjoyed viewing my 1st Instructable. Comments welcomed.

The charger has been programmed (via the meter buttons) for the load (LED strip) to illuminate for 3 Hours after dusk and 3 Hours in the morning before dawn. The controller needs no adjustment for this as it continually 'learns' when dawn and dusk is by monitoring the solar panel voltage - I like this feature.

Questions?

Ideas to improve?

how did your build go?

Comments welcomed.

Here is an update regarding the EP Solar remote display.

Note regarding the display of State of Charge SOC

I noticed that the display would show 100% when the sun was shining then would drop ~20% when the sun went behind a cloud however no charge was being drawn. I e-mailed the manufacturer with the following question.

================================================================================

"Dear Sirs

I have installed a Tracer 1210RN and MeTer system and have a question over the SOC readings. While the sun is shining the MeTer charges the battery to 100% no problem. Later in the afternoon (when no load is being drawn from the battery) the SOC drops rapidly to ~60%. I have checked the battery voltage (12V GEL type) and it still indicate 12.76 volts which suggests the 'real' SOC is about 85-90%. It seems as though the Meter is using the higher charging voltage as the 100% figure rather than 12.85V which is what it should be for this type of battery. Can you please comment."

====================================================================================

To their credit they replied with an spreadsheet attachment which I have attached here. The e-mail was as follows:

===================================================================================

Hello,

First, the determining of battery capacity is according its voltage.

It shoulds show 100% on the meter display when voltage is above 13.6V.

So it showed 50% on the meter display because its voltage was 12.8V.

And the detailed in the attachment.

===================================================================================

I'm not sure what to make of this information. The meter performs as per the attached algorithm but I don't understand why the meter seems to measure the charging voltage rather than the open circuit voltage? Perhaps the internal circuitry in the meter can not do this?

Anyway this is beyond my expertise to take this any further. Are there any battery charging experts out there?

With the help of my sister and a pack of Martha Stewart stencils we have added a touch of colour and uniquness to the bland beige box!

Martha Stewart Ferns Stencil

using a foam roller and a mixture of acylic paints (3 shades of green and one of brown) - I got these materials from a local artist supply shop. The techniques is to place layers of ferns with a first dark layer for the background. This is followed by a slightly lighter colour then a final light layer for the ferns in the foreground.

Have fun!