The practical answer is not as simple as it seems. If the house is on a flat, open desert, then conventional wisdom says to point photovoltaic panels north, and incline them at a tilt equal to the house's latitude. For example, if the house is at 30 S latitude, then tilt them at 30 degrees from horizontal. This provides the best year-round collection, roughly. However, local geography and climate dictate changes to this. If the house has a hill or building blocking morning sunlight, then it may make sense to point the array more westerly for maximum collection. You would also want to rotate west slightly if you know that morning fog or clouds are typical in the area. Or the opposite for an obstruction to the west. If the house is almost on the equator, it's advisable to still give the panels some tilt, so that water and dirt can drain off, and the owner won't have to constantly clean the array. In an area where snow is likely to collect on the panels, it may be better to give up on winter collection, and tilt at a shallower angle to get more during summer.

Solar water heating has slightly different concerns. It sounds like your area does not get hard freezes, so you would use the less expensive type of panel that does not have evacuated tubes in it. With that kind, air temperature matters, so often the best orientation will be northwest, to take advantage of afternoon heat.

For the space heating, unless there is going to be a huge collection area, I would go with passive, large, double-paned windows on the north side, that can be covered with drapes or moveable insulation when it gets too hot.

That's the general advice. To get actual numbers, you could write a program to optimize orientation based on actual data taken from the field. Then you could either obtain such data, or make some up, just to demonstrate how your program works.

See also this site http://rredc.nrel.gov/solar/calculators/... . And yes, there is data for Africa, look on the right bar.

If you are designing and building from scratch, build with the optimum roof shape for the building. Design solar panels that can be adjusted for the time of the year. The bottom of the panel can be hinged. Small motors can be used to lift the tops of the panels so they are closer to vertical in the winter. In the north, the sun is closer to the horizon.

You can then chart the electric generation so you can set the angles of the panels to optimize electric production from the data rather than from calculations.

Using solar water heaters if you live in the northern parts is too complex, heavy and costly. You would have to design a system that uses antifreeze. Pump the antifreeze into the house, then use a transfer mechanism to heat water in a tank inside the house.

As a rough guide for angling the panels, you point them straight south (in the northern hemisphere) and angle them from the horizontal equal to your latitude. This is 80-90% as good as using trackers and is simple.

Look up your insolation and see how many hours of good sun you get (it's usually between 4 and 7 in the US). Multiply that number by the wattage of your panels to determine the average watt-hour harvest you'll get. Conversely, if you know the amount of energy you'll need per day, you can divide that by the insolation to get the size of the array.

Energy harvest from a heat collector is usually about 7-800 watts/sq meter at full sun. If you have 1 sq meters of collector at 5 hours of insolation, you can collect about 4 kwh of heat energy per day, which is about 13,000 btu, or enough heat to raise 320 pounds of water (about 40 gallons) about 40 deg F. Of course, you'll need extra area for cloudy days and a well insulated water tank. You'll need to use a closed loop system with antifreeze if you live where it gets significantly below freezing. Most water heaters designed for solar applications have a backup electric heating element. An economical laternative can be to use a marine water heater that's designed to heat water using engine coolant (they're small though).

DK

I saw something a while back on some US government website, but can't find it. I think it suggested orienting fixed panels towards the south (north for you), and closer to vertical than is obvious, giving better performance in winter months when the sun is lower in the sky.

Or you can use heliostats to track the sun, either moving the panels themselves in 1 or 2 axes, or moving mirrors to reflect the sun onto fixed panels

I am working on a project for my civil engineering diploma. We have to design an energy efficient house. I am quite OK with insulation of walls , roofs , double glazing etc. But I want to incorporate photovoltaic cells to supply some of the electrical energy to the home , and also solar water heaters for domestic use as well as space heating.

My problem now concerns the optimum orientation of these units so that they are positioned in the most efficient orientation. I have spoken to some companies that install such systems , and they are mostly involved in retro-fitting to established houses , or they are contracted when the final design plans of a new house have been finalised. As a result they fit there units as best they can to catch the maximum sunlight. I am of the opinion that there is an optimum horizontal and vertical orientation of these units which can be calculated knowing the exact location of the proposed building ( GPS co-ordinates) If I can make these calculations I can specify the orientation of the house , and the roof pitch to support the units most optimally. The problem I now face is: How do you do these calculations. Does anybody know of a website that explains this or is there an established equation or method of working the orientation out , based on GPS co-ordinates. Is there any benefit ( or necessity) to have the mounting arranged so that it can be adjusted for different yearly seasons.

I would appreciate any advice available , - I hope that one day when I am qualified I can use this information when building my own home.