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Originally Posted by john61ct
Never leave the inverter going when not needed. Rather than buying a big one much better to buy a bunch of smaller ones "just enough" for a given circuit or even targeted per load device.
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I'm already doing that to a certain degree - not per device, but per group. For the few things that do not require too much overhead, this is easy - because otherwise I would have to overdimension every circuit. More importantly, all low-voltage devices (lighting, routers, etc.) have their own DC/DC converters so there is only one conversion stage instead of three.
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No buying PSW except where needed.
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I'm not sure what you are referring to here. What is a PSW?
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Also means less conversion losses.
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That's not universally true. There is a sweet spot, depending on the converter topology. A 10W converter, generally speaking, is cheaper and more efficient than ten 1W converters. But, on the other hand, a 1000W converter is almost always made out of five 200W converters strung in parallel. The limitations of magnetics and semiconductors dictate this. But it does support your point of having multiple smaller inverters, because they would fit into the "few hundred watts" zone. Unfortunately the $20 no-name 200/400/750W Chinese Harbor Freight inverters don't come even close to supporting this theory... I got several of all of them and they are beyond terrible
So in a way, I'm going in the other direction - I'm replacing a couple of terrible inverters with one better one.
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And most will be cheaper than a meal at McD's, can carry spares.
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I think you should reveal your inverter sources to us. Or pherhaps you live in Norway
https://www.thedailymeal.com/where-w...%20the%20world.
The main reason is that during the workday, we cannot have downtime, yet we may have peaky loads. We are both on billable calls, and the cost of an interruption with a client is much larger than the cost of equipment. In addition to videoconferencing and internet stuff (which is also on battery backup), there is also power hungry athletic equipment that needs to stay online. So for internet and power we have need failsafes.
There is another reason why I centralize certain things, and that is to minimize the RFI. One of the reasons why I do the RV thing is because I like to travel to radio-silent places to catch faraway signals in the low ferquency, medium frequency and high frequency bands. Cheap small inverters make an incredible racket that make it impossible to receive weak radio signals. My DC/DC converters are quiet because I designed them myself and they are optimized for interference, not so much for efficiency. I can afford that, power-budget wise, because the RFI suppression costs me just a few watts. Right now, none of the commercial inverters come even close to meeting standards, leave alone being usable for my purpose.
So when I buy one big inverter, I am going hack to quieten it down, radio-interference wise, and that one will run in the background 24/7. I want to be able to do my radio amateur thing without having to tell my partner that there will be a planned 120V blackout for the next 4 hours.
The third reason is consolidation of the overhead needed to allow for inrush currents on one large inverter. The fridge runs on 50W, but peaks at 700, for example. Other peaky loads, like the washer and the air compressor, would all need large individual oversized inverters, which is non-economical. Since they are used intermittendly, consolidating them makes sense here too.
Fourth, during the morning, there are peak loads that coincide: kettle, toaster, microwave. If I end up doing a kitchen-only circuit, it's going to be beefy. I considered doing a switchable cheap modified sine inverter for resistive loads, and a pure sine wave for the rest non-resistive loads. But it gets too complicated, and you better spend the money and have better performance.
Kazetsukai, I get back to your post later.