Solar Powered 12V lighting system

This project is about resilience more than energy saving, though it can also be used to save energy. Total costs should be in the order of £100, but there are ways to reduce that by getting some items from Ebay. The idea for the project came from the Transition Ipswich Energy group in 2011. It had to be targeted at a competent DIYer, and is for small scale lighting. This was originally published on TI’s website, which is no more.

This project lets you run lighting off of solar power, effectively storing sunlight for later use. It can be used at home to keep lighting during power cuts, but the same principle can be used to provide power to sheds on allotments, outbuildings or island sites without mains power. Although I have used lighting as an application, such a system can run an electric fence for much of the year if suitable solar panels and battery are used.

The system as described lets you run one or two 12V 1.8W LED lights through the year – my system was able to run mine through the winter and the shortest day where the light would be on from about 6pm to 11pm. In the summer you can also run a laptop computer power supply independently of the main for a couple of hours (these run typically 40W). That is because in the summer you get far more solar energy and you’ll probably use the lighting less.

If you want to primarily save energy or reduce your carbon footprint using solar power, this is not the solution. For that it is best to get a grid-connected solar power installation which will allow you to save energy and get renewable feed-in tariff payments. That sort of thing is on a different scale from this project, and capital costs are usually in the order of several thousand pounds, but the energy savings are much, much greater. A grid-connected solar PV system does not give you resilience against power cuts, because the anti-islanding systems in the grid tie inverter shut the system down if the main power fails, so that a PV system does not send power back into the grid when it may harm power workers trying to repair faults.



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Raspberry Pi camera after several years outside

It doesn’t pay to put a Raspberry Pi camera out directly facing the great British outdoors for more than a season even if you can keep the water out of it. I had a RPi Model B and camera doing just that and groused about the lens crazing problem where there seems to be some sort of microbial attack on the lens after a season outdoors.

damaged Raspberry Pi lens
you can just about see the grungy effect on this damaged Raspberry Pi lens which was outdoors for a season. The mechanical marks around the outside is because you have to break the glue to get the lens out. I did not mechanically damage the lens.

That didn’t respond to pretty aggressive scrubbing with isopropyl alcohol (IPA), and the Pi lenses are proprietary.

the lens on its own
the lens on its own

The back side of the lens not facing the elements looks fine

Sensor side of the lens
Sensor side of the lens

They are not standard M12 CCTV lenses1, so I got to buy another camera board, and used Sugru and a cut down glass microscope slide to try and keep it intact. I can buy aftermarket RPi compatible cameras using M12 CCTV lenses now, but then it wouldn’t fit in the PICE case.

Pi camera behind glass
The Pi camera is still bright-eyed after three years in the outside, behind a glass microscope slide

I left this camera out in the open on the farm for a while, and then watching my sparrows on the feeder. It looks like the glass slide technique has been a win, it’s been around three full years and the camera lens is still OK. The slide can be cleaned with IPA and comes good as new. Angling it down slightly reduces reflections and flare, but yes, it is uncoated so flare will happen. I built the Sugru up a but round the top to make a lens hood to minimse the amount of open sky that falls on the glass. Maybe the original Pi camera lens is plastic and gets eaten, although I know to my cost that optical coatings on glass can get hit by fungus too in damp conditions 🙁 Continue reading “Raspberry Pi camera after several years outside”

Hot composting using a wire mesh container

Wire mesh can make a cheap and portable composting container. We never had much success with this at The Oak Tree farm, probably because the site was very exposed to the wind, but Nigel Griffith at Landews Meadow Farm and Dave Beecher use this technique successfully.

We are trying this again at a new site which is much more enclosed from the wind, and we have the benefit of mains power for pumping. However, we don’t have borehole water, so we had to fill a 220l water butt with mains water1, and leave it to stand for a couple of days to vent the chlorine.

scrounged heap of chipped tree prunings
scrounged heap of chipped tree prunings

Materials were freshly chipped tree prunings scrounged from some guys who were trimming trees for the council and a combination of hedge trimmings, windfall apples and other green material. These were shredded using a domestic rotary garden shredder to this sort of consistency

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Wolf Supermoon

The first day of the New Year features a full wolf supermoon, 1 when the Moon is closest to the earth so brighter and bigger. The Moon was lovely so I figured I’d try for a shot. the Independent tells you why it’s a Wolf moon.

The Moon disc itself is as bright as the beach on a summer’s day when you are taking a picture of it, because it’s in full sunlight, no clouds and about the same distance from the sun as the Earth. Should be a doddle – I got the Canon EF 100-400 lens that I cleaned up, put it on a monopod and aimed at the Moon. f/8 1/400 ISO200 go.

Turns out not to be as easy as that. I needed a tripod, switched off IS and even then not every shot was equally sharp, must find the remote cable for the Canon, maybe it’s mirror slap. Took the best, that’s the top picture. I then tried my Micro Four Thirds camera with a 100-300 lens – the MFT sensor is probably smaller than the APS-C sensor on my EOD450D so the 300 end is probably comparable with the 400 on the Canon Continue reading “Wolf Supermoon”