Why a solar hothouse?
Well for one, Ballarat gets colder than most of Victoria due to it's higher altitude.
But also importantly, I also wanted to locate our new hothouse in a spot where it would get cut off from sun exposure earlier in the afternoon.
Many plants are susceptible to day length - they need a certain number of hours of light exposure even if they don't need a lot of heat during winter. By providing the extra light, plants grow quicker and also grow more consistently - they tend not to get stressed and "bolt to seed" early so you have a longer window to harvest them in.
So I will be using a simple setup to extend my 'day length' in the hothouse by about an hour of an evening.
To do this, a solar panel will supply power to a battery via a charge controller. The controller connects the panel if the sun is shining and the battery is not full. The controller also connects the load (the lights) if the battery has sufficient charge, and if it is dark. A cheap off-the-shelf controller can be set to do this at the end of the day as it gets dark.
I plan to use some off the shelf 3watt LED lamps to provide good clean light. LED's do not use much power, as they don;t generate much heat. And I don't need to heat to the plants, as the rotting organic material in my planting beds provides night time warmth, as do the bricks on the floor of my hothouse as they store heat from the daytime.
Parts:
- $100 Solar Panel (40watts)
- $10 Solar Controller with built in light control
- $25 Battery
- $15 Lamps
$155 might seem like a lot, but vegetables are expensive!
