Can an off grid solar system be used without batteries when the sun is up?

Hey Bobster, no, you can't. This is the Achilles Heal that many grid tied solar buyers found out the hard way when the first storm came through and knocked out the grid where they live. The next day after the storm clears, the sun comes out, but without a grid, they live in a powerless home even though they have 2000 watts of panels on the roof and the sun is shining.

Inverters come in 3 flavors today. Grid tie, which need an existing AC power source to synchronize with. If the utility line goes down, the grid tie inverter shuts down also because as you said, it has no way to regulate the incoming and outgoing energy variations. The second type is the stand alone, or "off grid," as you call it, which is like the inexpensive ones you buy at the auto parts store. They have to connect to a battery or some other continuous DC supply. They convert DC to AC as long as the battery is not dead and the AC load does not draw more than the inverter can convert. The third type is the Utility Interactive, which is more like a hybrid. It is designed as a stand alone, but has a synchronizing program built in that allows it to connect to the grid as well, or parallel with a generator. We have this type in our home now, it has the grid connected and a small battery bank as well. If the grid goes down, the inverter continues operating as a stand alone, so as long as the solar panels are keeping the battery bank sufficiently charged, the AC power continues to flow to the home.

So answering your question directly, no, an off grid inverter needs batteries, and cannot function without one. A grid tie needs the grid, and cannot function without one, and an interactive inverter needs one or the other. A stand alone unit can continue to operate with a large array and a very small battery bank, as long as the battery has a charge controller protecting it from overcharging. In this case, if the cloud passed over as you say, the small battery would have to provide for the inverter for just a few minutes. Our battery bank is nothing more than a couple golf cart batteries, and can run our refrigerator, deep freeze, and a few lights for up to 12 hours, enough to get through the night, which was the plan all along. There is no way to "balance," the power moment to moment between a solar array and an inverter without a battery or grid.

I also want to take a moment and caution you on getting information on these subjects from hacks like me online. I'm always amazed at how many people might answer a question like this with their expertise, having never laid a hand on a panel, inverter or deep cycle battery. In my experience using and teaching solar power the last 12 years, I've learned there are two things in vast supply, sun, and missinformation. Check out some better sources, like the library, and the non profit ones below. Take care Bob, Rudydoo

Solar Power Without Batteries

The solar panels produce energy at a certain rate which will be less than the rate at which you use the power at, you save up the power produced steadily but slowly by the panels in batteries or sold to the grid and use it back from the batteries or grid at the higher rates needed. You would need much more solar panels to use the power directly as you must then size them for peak usage instead of average usage. It would be a brown out as soon as your load is higher than the production.

The major consumer will be the refrigerator. For sailing yachts, there are refrigerators that use an eutectic plate/'holding plate' inside so they are powered only once per day for a few hours (from the 12 V alternator of the yacht's engine), then 'run' on the 'cold storage' of that eutectic plate (similer, but a bit more refined, to the blue ice packs you use for a beer cooler). Using such a refrigerator (and running it directly from the panel) will probably cut the expense for the storage battery by 90%. With TV/DVD player - there are a few types of integrated player/display (or even player/TV) LCD models that are intended to be used on the rear seat of a car (to keep children quiet on long trips...) that aren't too expensive and use only a little power (usually, they're run from a built-in battery). As to the light bulbs - for heaven's sake, use LEDs. Unfortunately, good LED lights that will survive for a few years in those climatic conditions(temperatures) won't come cheap. Battery charge controller: you might be able to get away without one, but that's the least of your problems (costwise), so why?

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use a dc motor connected to a dynamo which will produce ac current then use a voltage stabilizer of high quality.hope that wolud work