The Digital Agency for International Development

Solar Diaries - Day 10 - The Sinking Sun

By Alan Jackson on 07 October 2010

Last week ended with the battery shutting down. Because I wasn't working Monday or Tuesday I had 4 days to charge the battery back up. The weather has been cloudy so it was only half way through the fourth day that the battery finally had enough charge to be re-enabled.

There is the smell of autumn in the air reminding me that we're on the steep part of the sine (-ish) wave of rapidly shortening day length and presumably sun altitude. Last week the PV panel was out of shadow. I noticed half way through today that a good 25% of the panel was now in shade. With my head down frantically programming in python I didn't have time to extend the legs of the gridbeam frame. Instead I balanced the frame precariously on top of the compost bin.

The laptop started the day with a flat battery and so was drawing 5 Amps initially. I decided to forego the external monitor today. The laptop was was fully charged by lunch time so went down to 2 Amps. With the laptop suspended the power supply still draws 0.2 Amps so I unplug it for lunch. Unfortunately after lunch I forgot to plug the supply back in and didn't realise until a few hours later when the laptop was practically flat again. It recharged by the end of the day but just as I was finishing I noticed the solar battery was shut down again despite having a relatively sunny day today.

Starting Voltage: 12.2V Ending Voltage: 11.8V