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Buckshot0203
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# Posted: 26 Jun 2015 07:02pm
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dont know if anyone has the answer but i have a cabin i currently run with generator power and from the generator shed to the cabin is 220v then the cabin has a breaker panel where it becomes 110v and i have been thinking of doing a solar panel system for the cabin and i'd like to use the same wiring from the generator shed is there a way this is possible ? what would i have to do to make this possible
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bldginsp
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# Posted: 26 Jun 2015 07:13pm
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Yes, you can leave the wiring from the generator shed to the cabin the same. You will need an inverter in the gen shed to convert the battery power from DC to AC. You just need to have designed a standard solar system with panels, charger, batteries and inverter. But, if you plan to switch the power source from solar to generator, you will also need a transfer switch.
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Buckshot0203
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# Posted: 26 Jun 2015 07:23pm
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well my generator is connected via a large plug could i just wire in an outlet in the gen shed instead of a transfer switch?
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MtnDon
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# Posted: 26 Jun 2015 07:53pm - Edited by: MtnDon
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If it makes any difference to you, removable plugs are not accepted by the electrical code. Code calls for inverter and generator inputs to be hard wired and in conduit.
If you are running 220/240 from the shed to the cabin that does possibly complicate things. There are very few inverters that provide 220/240 volt AC, 60 Hz power. Most are 110/120 VAC. Most of those can not be stacked to provide 220/240 VAC. The problem is sync'ing the phases of the two inverters. Some, like Outback, are made for stacking. Magnum makes at least one inverter with 220/240 output.
Do you actually need the 220/240 VAC? Like maybe for a well pump? Depending on what your actual power need is it may be less costly for equipment to change to 120 VAC.
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Buckshot0203
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# Posted: 26 Jun 2015 08:46pm
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i dont see how i could possibly hard wire this generator as it is a portable generator but thats neither here nor there its not something that makes any difference to me as this is not a permanent residence at least not for the foreseeable future. just a getaway cabin.i'm not exactly sure why my dad set it up to run 220 from the generator to the cabin not sure if it is something to do with the breaker box or what i do know everything i have out there is 110v pump and all. instead of running it through the same line as the gen set could i just hook up a 110v setup and wire it into the breaker box from the inverter ? and still use the same stuff inside the cabin?
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MtnDon
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# Posted: 26 Jun 2015 09:48pm
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I simply mentioned the hard wire rule as a caveat in case there would be inspections.
Quoting: Buckshot0203 could i just hook up a 110v setup and wire it into the breaker box from the inverter ?
You could run a wire for just 110, yes. But then you'd have a 220 and a 110 and run the risk of somebody hooking everything up at the same time and perhaps killing someone. That's part of the reason NEC doesn't allow plug-ins and demands transfer switches so dangerous events are less likely to occur. Transfer switches help prevent "boo-boos".
Also a service panel fed by 220/240 is set up to divide that into two separate 110/120 legs. Having a 220/240 source or line and a 110/120 would make that very messy. Lots of potential dangers too.
Doing away with the generator 220/240 altogether might be easier and safer. The generator likely has 110/120 output as well. Depending on how much power you use that could be the simple ticket. Or maybe not as there is much about the system you have we are guessing at.
If any of what I said seems a puzzle your best bet may be to hire an electrician.
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Buckshot0203
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# Posted: 26 Jun 2015 09:56pm
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the generator is set up for 110 also and i am pretty sure the reason he installed the 220 was to put it a few seperate circuits in the camp and because it was the stuff we had at the time (built as much on the cheap as we could) as we had taken the electrical out of our garage at home. i'll probably just run a totally seperate system for the solar if i can ever afford to do it. thanks for all of the info
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bldginsp
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# Posted: 27 Jun 2015 03:45pm
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So Don are you saying that the majority of off-grid inverters are not set up to deliver 240v? All the grid tie inverters are- they connect at the service with a double breaker to both legs of the phase.
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MtnDon
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# Posted: 27 Jun 2015 04:22pm - Edited by: MtnDon
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Quoting: bldginsp the majority of off-grid inverters are not set up to deliver 240v
Yes. 120 VAC is pretty much the norm for off grid inverters. Grid tie is a whole different thing.
There are some off brands I have seen that put out 240 VAC. They are not stackable just like the vast majority of low end and mid range are not stackable. That may or may not be a problem. I also really am not a fan of off brand inverters due to personal experiences with them as well as a few issues getting an off brand serviced. But that is my prejudice showing I guess. I have not seen any of those that have hardwire provision either.
Outback builds all their off grid inverter/chargers in 120 VAC for our market and to be stacked series for 240 VAC as well as being stacked parallel for more current. Ditto some Xantrex/Schneider and some Magnum. All these can be installed 100% NEC compliant.
FYI, one other nice thing about Outback and some Xantrex/Schneider inverter/chargers is that their built in chargers can be programmed to a certain max. amps into the battery or a maximum number of amps drawn from the generator. They also employ a soft start for the charger. That is nice for the generator rather than it being hit with a huge surge like with most all other brands of inverter chargers or stand alone battery chargers. The Outback and Schneider also have excellent Power factors. High PF means less wasted electrical energy and more power into the battery for the generator fuel used. PF article for reference
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bldginsp
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# Posted: 27 Jun 2015 07:14pm
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Good information- I'm still a way from doing a solar installation, and it seems like they keep refining the electronics with each new generation of equipment, so by the time I buy perhaps all inverters will have refined power factors and be stackable. But perhaps not- there's always a market for the cheap stuff and stuff with less features, even if well-made. Every instal is a little different and in some cases simpler is enough if not better.
Seems like they are refining the ability of chargers to deal with the quirks of lead-acid deep cycle batteries, but soon the larger lithiums will come out, I wonder what sort of needs those units will have for chargers. All this careful refinement of how we charge lead acid may become useless technology sooner than we think.
In my particular situation my panels will need to be about 700 ft from the charger and batteries, so I will be looking to bump the string voltage high enough to get the wire size down to a reasonable cost. Doesn't seem to be much middle ground with high voltage charge controllers. The majority will receive up to 48 volts, then a few up to 250, then a few at 600. The 600s are $1200 and can send 50-60 amps to a set of batteries. That's a lot more amperage than I will be delivering, so I'm hoping to find a high voltage controller at lesser amperage capacity that costs less.
With a string in series putting out 600 volts I could probably use #14 wire to send the power up the hill! Pretty amazing.
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MtnDon
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# Posted: 27 Jun 2015 07:38pm
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Be aware that the greater the difference in the voltage coming into the CC and the base voltage of the battery pack, the greater the voltage conversion losses in the charge controller. Everything is a trade off...  That means having a careful look at everything. Maybe meaning a 48 volt battery bank is worth looking at? Also maybe meaning a look at heavy gauge aluminum wire instead of copper for that 700 feet. All depends on the commodity prices.
I am looking forward to the day Midnight Solar gets their inverter/charger line ready for prime time. (The guys at Midnight are the same ones who owned, started and engineered Outback's debut products and those of Trane way before that.) One of their proposed features is to have a dual inverter. Something like 300 -400 watts output for most things, with an instantaneous and seamless switch to the higher range, say 2500 watts, maybe more. The idea being to try and make the standby/idle losses as low as possible. Low range for all the ordinary stuff and higher output for those devices that demand more. (For example a 2500 watt inverter wastes a high percentage of the power being made when used to power a few lights and a TV; low wattage loads).
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bldginsp
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# Posted: 28 Jun 2015 11:20am
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Good info Don. I have some planning to do...
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creeky
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# Posted: 28 Jun 2015 12:19pm
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Keep an eye on the Victron equipment now coming to the North American market. the european mfcts are really benefiting from a larger market base and providing proven top quality gear.
They have an easy solar all in one out now. Literally a solar charger, inverter, charger, transfer switch even the ac distribution box all in one box. how easy is that.
Plug your panels in. Plug your ac circuit wires in. you're done. and it's pretty much perfect for a small solar system.
One thing about idle losses etc. (Can you guess what's coming?) Okay line losses less than 3%. Charging losses converting from High voltage to Lower voltage (up to 5% give or take). Idle losses/inverter losses. Usually around 7% for good equipment 12% for older style inverters.
But your biggest loss is going to be your battery charging inefficiency and self-consumption. By a large amount.
For someone with a 700 foot distance from solar to storage BI you need high voltage panel sets to reduce cost and line loss. But all your losses are minimal compared to what you'll lose from the wrong battery tech.
Luckily lithium is available now. There is no need to wait for the future.
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creeky
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# Posted: 28 Jun 2015 12:38pm
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and sorry Buckshot. didn't mean to hijack your thread.
But yes to both your questions. You should be able to use the existing wire. I don't know how your dad wired the 220 down to 120. I assume he was sending two 120 legs? Then just hook the inverter 120 into one of the legs.
Most of us on solar also run small portable gennies that plug into the panel. Sometimes on a switch. It's not hard to be your own manual transfer switch.
The advantage of switching is it takes the load off of your inverter while charging your batteries. It's also useful to run large loads too big for a small power inverter but the genny can handle.
I ran a home made power cord that I plugged into the genny for over 5 years. Did finally break down and buy an ATS for this winter. But I'll still manually plug and unplug from the genny as I need to be able to move it around the farm.
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