Quote "I am unable work out an answer for this question, because you cant really convert KWh to KW."

Absolutely CORRECT. This question has been asked a number of time. Take for example

a 20000 watt demand for only 1 hour = 20 KWH.

a 1 watt demand for 20000 hours = 20 KWH

When you build you power plant do you use a demand of 20000 watts or 20 watts?

If you use the 20 watt your plant may be smoke.

You must calculate what the peak demand will be and I do not know what you mean by "Assume the capacity factor of the power plant is 11%.". Do not assume.

Wareagle,

Thank you for your point about judging the peak demand - I think thats key.

Btw...by capacity factor I mean: actual power output of the plant divided by the rated output of the plant.

So for example, solar thermal plants normally have a capacity factor of ~25% and if you want to have a solar thermal plant with a output of 100 MW, you would have to build a 400 Mw rated plant, because solar thermal plants have low conversion efficiencies compared to coal plants

What course is this for?

I don't know if your "Suppose" is correct. My house is using about 250Kw to 300Kw/month. You got to get the facts and data correctly before you can size your power plant. If you are talking about each house use about 20Kwh/month, I think there is some facts are not correct.

For 20Kwh/month, that means that each house used 27.7watt/hr. Even one fluorescent lamp will consume 36watt/hr.

You need to do more research and collect more data's on the power consumption on each house so that when you size the power plant, at lease you know what will be the extra capacity needed for future plans and demands.

The consumption levels are really low, because the number(25Kwh/month) I quoted are actual average consumption levels in rural locations in developing countries. I am trying to figure out what the capacity of a community based solar or biomass plant has to be in order to serve 20 such households.

Generator or power plant, that generate the power supply for the consumption is calculated base on KWH of power consumption, assuming that the power consumption is constant thru out the whole day.

Since each household energy consumption is about 20Kwh/month that means that for 1 hr of energy consumption is about 20,000 watt/(30 (day) x 24hr) = 27.7watt/hr/household.

Total power required for 20 household is = 20 x 27.7watt/hr = 555.55 watt/hr. (or 0.555Kwh)

If you wan to size the power plant, you should also to consider the voltage drop, losses, sudden inrush in power demand, generator efficiency and few more other factors.

The above calculation is assumed that the entire households are consuming the power in every hour.

For conversion of KW to Kwh, actually there is noting to convert. Just multiple by the hour of consumption and you will get Kwh. For example;

If you have a equipment that is rated at 1KW power and operate it for 1 hr, that mean the power consumption will be 1Kwh.

If you have a equipment that is rated at 1KW power and operate it for 40 minute, that mean the power consumption will be 1000KW x40 minute/(60 minute) = 0.666Kwh