Cost Analysis Among Three Power Backups

This is the best solution. very cheap.

Hmmm...

"Cost estimate" is a little too vague for my taste.

Installed cost? Operating cost? Long term cost of ownership?

Inverter / battery cost considerations:

• Components (inverter, batteries, battery charger, cables, adequate framework to hold batteries (higher if in a seismic area), ventilation, effects of ventilation on HVAC system costs (if any)
• Labor for installation
• Cost of utility power to charge batteries and float them
• Battery maintenance / replacement over time, including disposal

Solar PV system cost considerations:

• Components (solar panels, inverter, cables, adequate framework to hold panels (higher if in a seismic or high wind area)
• Labor for installation
• PV panel maintenance (cleaning), including replacement of dead / damaged panels, disposal.
  
• ALL of the above costs for a inverter / battery system above

Generator system cost considerations:

• Components (generator, transfer switch, cables, fuel storage facility, leak detection, level monitoring system, fire suppression system).
• Labor for installation
• Fuel, delivery / transport, spill containment / mitigation, future clean up.
  
• Generator maintenance (oil changes, cleaning, replacement parts, labor).
  

You state the load will be 500W but do not state the voltage. Based on your currency conversion info, I will assume TSH = Tanzania - 230V @ 50Hz.

The following is based on a self starting, maintained system;

A generator will require a transfer switch, electric start on the gen-set, fuel supply and interconnecting conduit systems. Estimated Installed Cost: $7500.00

A solar system will require a solar array (collector), inverter, batteries, and related conduit systems. Estimated Installed Cost: $5500.00

A UPS System will require a place to mount it.

500 watts @ 230 volt for 5Hr will not require a huge capacity.

My choice would be a 750 to 1000 Watt UPS System.

The UPS vendor will be able to help you out with the required battery configuration to maintain back-up for 5 hours.

My estimate of a 750W - 230V - 50Hz UPS System with 5 hour reserve would be $700.00 to $1000.00 (USD).

Disclaimer: My dollar estimates are just that - estimates based on my local codes and vendor pricing.

A search on Google of "ups 750 watt 230 volt 50 Hz" is a good place to start looking.

Here is a link: http://www.google.com/search?q=ups+750+watt+230+volt+50+Hz&sourceid=ie7&rls=com.microsoft:en-us:IE-SearchBox&ie=&oe=

Hope this helps - Good Luck!

KJK!

Thank you for your comment,I real appriciate your response.

Best regards

Here are some generators, including some quiet RV (recreational vehicle) types of 1500 watts for about US$300.

http://duropower.com/?gclid=CJH1j5WIhKYCFRiAgwodlRFRqQ

For the small size of the load, a "transfer switch" could consist of a simple plug that would attach either to the generator or the grid, with no chance of cross-connection. You would want a pilot light still on the grid so you could tell when power is restored.

Ths is all manual, of course, but it looks pretty cost-effective.