A Solar Powered Ham Radio Station ROB NORMAN (VK5SW) http://www.eham.net/articles/20948 "A Solar Powered Ham Radio Station Since I wrote the article called ' Modest 20 foot Tower ', I've had enquiries, wanting to know more about my 'Solar Powered Station in the Bush'... There's an interest, nowadays, in alternative forms of power but the most popular for Amateur Radio Operators would have to be Solar Power... The problem, however, is that I don't know much about it but I can share with you what I do know... I've been operating my ' Solar Station in the Bush ' for a couple of years now and it's been working very well, although my situation is probably a little different to most, in that, we use our property as a ' getaway ' and we're only there for a few days each month or so, and therefore the demand on the battery is infrequent... There are basically 3 components to a Solar Installation... The Battery, the Solar Panel and the Controller to regulate the current going into the battery... It's basically as simple as that... The sizes of these, depend on the amount of current you need to draw from the battery and the duration... Once you work out these 2 requirements, you're able to figure out the capacities of the 3 components... In my case, for example, I operate CW on HF, so the current draw on the battery would be about 20 Amps or so, although I only run the radios at about 75% of full power, ie 75 watts... So, let's say the current demand is about 20 Amps anyway... If I was to run the transmitter for 1 hour, it would mean that the battery has used 20 Amp Hours in that one hour period... Batteries are rated in terms of their voltage and the number of Amp Hours that they can supply... However, batteries used with solar panels need to be of the ' Deep Cycle ' type... They should only be discharged up to and no more than about 20% of their capacity... If, for example, you have a 100 Amp Hour battery, it shouldn't be discharged by more than 20%. ie 20 Amp Hours so that 80 Amp Hours of the battery's capacity should still be available... The battery I use has an Amp Hour rating of 670 Amp Hours... 20% of that is approximately 130 Amp Hours... So, I'm able to draw that amount, 130 Amp Hours without harm to the battery... Most people would think this to be ' Overkill ' but I tend to do this sort of thing... Therefore, if the transmitter was to run for 6 and a half hours, at 20 Amps, the battery would be down to the allowable ' discharge level '... There are many different types of batteries available nowadays, but I bought a lead acid type, made by Exide in the USA, because it's a proven and reliable type of battery, old technology... It consists of 2 volt cells in series to form 6 volt batteries, 2 of which make up the 12 volt supply... A battery this size can power a small house but you would need a number of panels to recharge the battery due to the regular current drain by house hold appliances etc... They're not cheap... This one cost $1500, Australian, a couple of years ago and the expected life is about 10 years if looked after properly... The voltage at the battery fluctuates with the current coming into it from the panel... It may swing from 12 volts or so of a night to 14.5 volts or so in the daytime... I have 3 different radios that I have used with this battery and the voltage swing doesn't seem to affect them... The amount of charge going into the battery is dependent on the size of the panel, it's direction towards the Sun and the availability of Sunshine... Since we're not at the Radio QTH all the time and drawing current, the battery doesn't need to be charged quickly on a regular basis... One 80 watt panel is sufficient for my needs ie. to keep it charged... It's made by BP and cost nearly $700 Aust... The direction that the panel faces is important to maximise the exposure to the Sun... Also, the angle to the horizon should be optimized to ensure that the Sun hits the panel as near as perpendicular as possible throughout the year... High tech ones track the sun... http://www.eham.net/data/articles/20948/Controller.jpg A.jpg The ' Charge Controller, ' or ' Regulator ' ensures that the right amount of current from the panel is fed to the battery... When there is a large current drain from the battery, the regulator will allow maximum current to flow into the battery from the solar panel... With the panel shown, a maximum current of nearly 5 Amps can be produced with a cloudless sky... When the battery is nearly fully charged, only a small amount of current is sent to it... The maximum Amp Hours this panel can manage at this QTH seems to be about 35 AH or so a day ... When buying the battery and panel, the sales people will sell you the appropriate controller as well... The charge controller is able to tell you a lot of information... eg. the voltage at the battery terminals at present, the amount of current going into the battery at the moment, the number of Amp Hours already gone into the battery so far today, the total Amp Hours sent to the battery each day etc... The other consideration is the wires connecting components... To reduce voltage drop, ensure that you use heavy gauge wires and also use fuses in the main lines... Ask the sales people questions, they want your business... I hope this is of help in building your own Solar Powered Station... You can see mine, here, at VK5SW 73's for now... Rob - VK5SW... "