Your January Tropical Homestead Checklist

The daily numbers above come from PVGIS, a free solar tool from the European Commission's science service.

So use the extra power now. Run the water pump, the washing machine and the power tools in the middle of the day, when the panels make the most. Whatever the battery can't hold is simply lost.

Heat is the battery's enemy. Many lithium iron phosphate batteries (LiFePO4) may only be charged up to about 45 °C, and some datasheets allow 55 °C. A battery box under a tin roof can get that hot.

Old-style lead-acid batteries hate heat too. A common rule from battery makers says their life is cut in half for every 8 to 10 °C above 25 °C.

To protect them, keep batteries in the shade with air moving around them, and check the datasheet for the safe temperatures of your own model. Our guide to lithium batteries explains what's inside them and why heat wears them out.

In the dry season every litre counts. On Guam, the university's farm advisers say irrigation is a must from January to April, because little rain falls and the wind dries the soil.

Water early in the morning, while the air is cool, so more water soaks in and less floats away as vapour. Late afternoon is worse: wet leaves at night can invite plant diseases.

Even better is drip irrigation: thin hoses with tiny holes that drip water right at the roots. The same Guam experts say a well-made drip system keeps more than 95% of the water in the root zone, where plants can use it. Shower and sink water from the greywater setup in November's list can go to the fruit trees.

So what should you plant in a dry season garden? In many tropical climates this is the best vegetable month of the year: cooler nights, drier air and fewer leaf diseases, so plants thrive.

Water young plants in well, because thirst is what kills them. December's list has more on dry-season tomatoes.

Then the shade question. Shade cloth is a loose woven net, a bit like a mesh football shirt, that blocks part of the light. The University of Delaware says cloth that blocks about 30% of the sun is the most common choice for vegetables.

In the cooler months you may not need it. In a University of Hawaii trial, lettuce grew heavier heads in full sun than under 30% shade in fall and spring, and shade helped only a little in summer. So if plants wilt at noon, shade that one bed first and compare growth with the rest. Our off-grid garden guide covers soil, water and how much space a family needs.

A dark roof in full sun can reach 65 °C or more, hot enough to burn your hand. A light "cool roof" can stay more than 28 °C cooler, says the US Department of Energy.

That heat soaks down into the rooms below. Then fans or air conditioning have to fight it with battery power.

Fans help, but only up to a point. The CDC, the US health agency, says to use a fan only while the room is below about 32 °C. Hotter than that, a fan can actually make your body warmer.

In places where dry-season nights cool down, open the windows after dark and close them in the morning to trap the cool air inside. Our guide to off-grid cooling has more tricks.

A compost heap is a pile of food scraps and plant waste that tiny living things slowly turn into food for your plants. And those tiny workers need water to live.

A good heap feels like a wrung-out sponge: damp, but not dripping. If it gets too dry, the US Environmental Protection Agency says, the work inside slows down or stops.

So water the heap when you water the garden, and cover it with a layer of dry leaves or an old sack to slow the drying. A shady spot protects it too. Our guide to home composting shows how to build a heap that works.