For system back up and battery charging.
Many people relying on solar equipment as their main source of electricity for most household items also have a conventional motor driven generator to use whenever high powered equipment such as the humble washing machine or water pump need to be used. They may also use the generator to power a battery charger during times of bad weather (or visitors!) when energy use is high and the battery is low. In larger systems the generator can become an integral part of the installation being started automatically, running the high power load AND charging the battery at the same time (providing the generator can supply enough power).
Whatever the size of alternative energy installation, if it is to be relied upon 365 days a year, common sense usually prevails and a generator that can provide an instant solution to a power shortage is purchased to ensure “ normal” life may continue .
Generators are available made by many different manufacturers in many different sizes (both electrically and mechanically) and so choosing the correct one for the job seems to be difficult. To start with we need to know the TOTAL amount of Watts the generator is expected to have to deliver at any one time.
So, if you want to run a Washing machine of 2500 Watts at the same time as a 2500 Watt water pump your total expected continuous Watts is 5000. Unfortunately, pumps typically require a lot more energy to get started and so the peak power requirement will be much higher than 5000 Watts.
To avoid poor fuel economy and running a generator too near its maximum output rating for any great lengths of time, I would recommend a generator capable of continuously supplying between 10 and 25 % or MORE than your “expected” total. This may seem a large amount of headroom to suggest until you think that not many people would drive a car at 75% of its potential all the time and expect it to last!
After we know the power requirements we can then try to select a generator that will meet them , only we have to narrow it down a little bit more first. Just some of the questions that should be asked are: Would you like Petrol, Gas converted or Diesel engine? Manual start or Electric key/button Start or maybe even a Fully Automatic Starting model? These questions and more usually answered with more questions about purchase prices? Is it noisy? Where to put it ? How big is it etc..
Battery Chargers
Professional quality high output battery chargers are available, enabling safe re-charging of large batteries frequently used in solar systems. These chargers are a lot more powerful than your standard “car” charger but still will take some hours to carefully re-charge a large battery, do not expect all to be tip-top after half an hour with the generator on. If we have grid mains electric we would leave a small car battery to charge overnight for around 10 hours before trying to use it again. For every size of battery there is an optimum charge rate and so the correct charger has to be selected to prevent damage to the battery, particularly by charging too fiercely, as a guideline allow a maximum charge rate of around 0.15 x Battery size(Amp/Hours). Battery chargers of quality will feature as standard 3 step charging (see regulators page) to help charge efficiently, although probably would have fixed voltage settings, so these should be as “ close” to the battery manufacturers recommendations as possible .
