Using a Conventional Generator Set
Rather than have a hybrid independent power plant, why not just use a solar-charged storage battery bank with an inverter, and use a conventional petrol generator (like the cheap ones that you can buy at an automotive-accessory or hardware shop) to run your household when your storage battery bank runs flat? There are a few reasons why this is not a good idea
Damaging the Storage Battery Bank
The storage battery bank is the most expensive and most easily damaged component of your system. Deeply discharging a storage battery bank before recharging it damages it and reduces its life. This is exacerbated if it is left discharged for a long period, and if it done repeatedly.
This means that letting for the storage battery bank run flat, while hoping that the sun comes out soon, before switching to a petrol generator will shorten the storage battery bank’s life. To get the best life from your storage battery bank, charging and discharging
must be carefully controlled.
A well-managed storage battery bank may last twelve to fifteen years; inappropriate charging and discharging with a poor-quality battery charger will be likely to reduce that by half.
Charging Storage Batteries
A petrol generator produces mains-style AC electricity, which can’t be used directly to recharge the storage battery bank. To recharge your storage battery bank from the petrol generator you will need to buy a large-capacity, expensive, specialised 24- or 48-Volt battery charger.
A poor-quality battery charger can damage your storage battery bank by overcharging it or by charging it incorrectly.
Independent Energy Solutions
Direct connecting the petrol generator to your house If you want to bypass your storage battery bank and connect your petrol generator directly to you household electrical system, you’ll need an electrician to set up the connection for legality, safety, and to isolate the generator from your solar system’s inverter.
Most cheap petrol generators are synchronous generators, which produce a poor-quality waveform that may damage electronic equipment such as a DVD player, computers, and microwave ovens if they are connected directly.
A cheap petrol AC generator uses a lot more fuel than a high-quality diesel DC generator and will have only a fraction of its life-span; in the long term this will result in a higher overall cost for y our electricity.