Many buyers do not have the knowledge in Electronics about Power Inverters used to convert Solar Panel power (12 or 24V) to mains supply 110 or 240V AC. A 12 Volt system needs about 18V from a solar system to work effectively. To run devices with clocks and timers a Pure Sine Wave is essential not a modified sine wave which has a sawtooth output.
If your coffee maker is rated at 1.5KW then you will need up to 8 times that figure to handle switching surges, so do not buy a 3KW inverter because you are going to blow it apart after a short while.
The biggest question is HF or LF (high or low frequency) Many sellers do not disclose this so "always ask" an HF inverter uses FETs (Field effect transistors) to switch the DC input and convert it to an AC wave form this is stepped up by using a bank of HF chokes to 240volts, which is then processed by the following circuitry. These FETs are often under-rated and may only last about 3 to 4 years if you are lucky, often the TVS diodes (transient voltage suppression) with blow apart if the FETs are overloaded, also taking out the fuses. Importantly an HF inverter can only handle up twice the continuous rated power ie 1KW continuoous 2KW peak.
Basically they are a waste of money.
LF inverters are are the only way to go. OK you will pay more, but instead of a bank of small chokes and FETS they use a huge toroid step-up transformer, which can weigh many kilograms, an 8KW continuous rated unit can weigh in at 23 Kg! So do not be surprised the postage is higher! LF inverters can also handle up to 4 times the rated power ie. 8kw continuous 32kw peak.
An 8KW unit will handle most kitchen appliances, TV and small fridges provided the total consumption at any one time does not exceed 2KW.
Conclusion: Be very careful what you buy so as not to be disappointed. Parts are readily available to repair these inverters, but should only be carried out by a qualified and experience technician. Dangerous high voltages are present inside the units, (More so in HF units in places you would not expect) that can kill or serious burn or cause batteries to catch fire. Solar batteries are usually rated at 100Ah (Amp hours) and if shorted can melt a screw driver tip or burn heavy cables if shorted out!!! Do not open the cases if you do not have the knowledge.
I suggest that before you buy, you contact the seller and tell them what your needs are and what you are going to run on the inverter and ask them to suggest an approriate unit. In any case always go for the LF version and not be tempted by the cheaper "throw away' HF versions. Any seller worth his salt will be only too happy to assist you. If you get a nondescript reply, then look elsewhere. In all cases good solid Power inverters do not come cheap and avoid the HF versions they are inefficient, whereas the LF inverters can be over 90% energy transfer efficient. .
I hope this will assist you and save you headaches down the track.
(65 years experience in the electronics industry) ...DLS.
Thought of the day: Caveat Emptor (Buyer beware) .
