peakbagger said:
I see nothing wrong with the word "simulated" in this context. Over the past 50 years that I've been using inverters - I have seen many "work-arounds" to make AC power from DC with an effort to mimic the 60 cycle sine-wave. My use of "simulate" simply connotes an inverter that does not make a true 60 cycle sine-wave. It DOES make something close enough that the vast majority of AC applicances will work fine on it. If you feel better with terms like "square wave" or "modified sine wave" - that's fine but it's just another way of saying the same thing.
peakbagger said:
There are few regulated controls for any of them -when it comes to qualilty, durability, etc. The oversight involves the quality of the AC power coming out, and little else. What HAS added some "de facto" regulation is the insistance of some State incentive programs to have a 5 year warranty on ALL equipment. When I bought my Outback grid-tie inverters they only came with a standard 2 year warranty - but the Outback company had to extend their warrantees or lose grid-tie sales. Note though that they did nothing to make the inverters more rugged. They just jacked up the price to create their own sort of insurance policy for a longer warranty.
As to price? Anything that is a specialty product gets priced higher. Solar grid-tie is a specialty, AND the mind-set is that most who install it are getting price-support somewhere (e.g. State and Federal incentives or grants). And of course, grid-tie units are NOT just inverters. They are much more complicated then that.
I can buy two identical solar panels - same size, brand, and off the same assembly line. Yet if I opt to buy one without the UL certification, I can often buy for near half-price.
My experience with off-grid solar electric has obviously been different then your's The cheaper inverters that do not produce a true sine-wave have been the mainstream of the industry for many years and are still common. Most installations I know of keep a mix of both. The more expensive sine-wave inverters are often just used for the few pieces of equipment that need it. What has changed recently is the availabilty of combo inverter/chargers in the cheaper format.
For anybody that's asking inverter questions though -keep in mind that "inverters" sold specifically for solar use - grid-tie or off-grid of often not just inverters. They often have many more controls and features added.
One example is my Trace/Xantrex DR2412 2000 watt off-grid unit. It has a built-in automatic 120 amp battery charger, it has a built in demand swith so it can turn itself on when AC power is needed. It also has a battery temperature probe that determines proper battery charge by temp, type of battery and size of total battery bank. It can also remote-start an electric generator to charge the battery bank if needed when the sun is not available. This "inverter" weighs 50 lbs whereas a 2000 watt inverter from Harbor Freight or AIMs for $150 will only weigh around 12 lbs.
Off-grid will have a battery bank and thus must have a battery charger, probably a fuel-driven generator, charge contollers, etc. It will also have low voltage solar-panel array.
A mainstream grid-tie has different needs. Usually no batteries so no charge contollers needed. Solar panels are usually set up for very high voltage so the inverter does not need a lot of step-up wiring. The AC power though has to be certified to meet power company regs. It also has to sense a "grid-down" situation and shut itself off. These units can be extemely complicated and I many have get design changes fairly often as regs change. This adds to the prices.
