Inverter????????

tmarch
tmarch Solar Expert Posts: 143 ✭✭
in Solar Beginners Corner #1
I have 6 Suntech 175W 24Volt panels. Looking for ideas for an inverter to use with them to supply power for a small shop.
I have a generator for bigger items, but often all that's needed is a fan or small drill and running the generator is not only costing me fuel, but the noise is distracting. (listening to the dollars burn away:cry:)
I'm thinking of adding panels as I go so is there an inverter that would allow for that?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Inverter????????

    are we talking gt or off grid?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Inverter????????
    tmarch wrote: »
    I have 6 Suntech 175W 24Volt panels. Looking for ideas for an inverter to use with them to supply power for a small shop.
    I have a generator for bigger items, but often all that's needed is a fan or small drill and running the generator is not only costing me fuel, but the noise is distracting. (listening to the dollars burn away:cry:)
    I'm thinking of adding panels as I go so is there an inverter that would allow for that?

    There's no such thing as a yellow cat with purple ears.
    There's also no such thing as an off-grid inverter that runs directly from solar panels with no batteries.

    Off-grid Rule #1: No batteries = no power.

    Fortunately your 1050 Watt array will support a fair amount of capacity. 270 Amp hours on a 24 Volt system. That's up to 3 kW hours, roughly speaking. And that could run quite a number of power tools fairly well for quite some time. The problem with shop power is that it is highly unpredictable. But since you do have a generator if you should run out of power you can recharge as needed (and probably would do so any time you needed to run the gen).

    In a case like this you could go for the panel limit (about two parallel banks of 6 Volt 225 Amp hour golf cart batteries - around 450 Amp hours @ 24 Volts) or just put in a basic 12 Volt system with the same Amp hour specs and have plenty of charge power.

    Lots of possibilities here.
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  • tmarch
    tmarch Solar Expert Posts: 143 ✭✭
    #4
    Re: Inverter????????

    Ok sorry wrong question, and this is probably wrong too but...........
    6 175 watt 24 volt panels, + 6 Enphase inverters (M190) to allow for more panels as I can afford them.
    How many batteries just to get the power produced? NOT wanting to get any more than necessary as I won't be using the batteries for anything but getting the power from the panels.

    This is off grid.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Inverter????????
    tmarch wrote: »
    Ok sorry wrong question, and this is probably wrong too but...........
    6 175 watt 24 volt panels, + 6 Enphase inverters (M190) to allow for more panels as I can afford them.
    How many batteries just to get the power produced? NOT wanting to get any more than necessary as I won't be using the batteries for anything but getting the power from the panels.

    This is off grid.

    Nope. Not with Enphase inverters; they are grid-tie microinverters. They don't connect to batteries and they don't produce electricity without grid power to synchronize to.

    Let's go back to Square One and ask what is you're trying to achieve? Reduced electric bill? Off-grid power supply? Emergency back-up power?
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  • tmarch
    tmarch Solar Expert Posts: 143 ✭✭
    #6
    Re: Inverter????????
    Cariboocoot wrote: »
    Nope. Not with Enphase inverters; they are grid-tie microinverters. They don't connect to batteries and they don't produce electricity without grid power to synchronize to.

    Let's go back to Square One and ask what is you're trying to achieve? Reduced electric bill? Off-grid power supply? Emergency back-up power?

    Basically trying to do what was in my original post for a off grid shop. Just looking for suggestions to run some of my smaller tools and fans etc.
    For the larger stuff I have the generator.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Inverter????????
    tmarch wrote: »
    Basically trying to do what was in my original post for a off grid shop. Just looking for suggestions to run some of my smaller tools and fans etc.
    For the larger stuff I have the generator.

    Ah. The conundrum of "how much power does a shop use?"

    You really can't get away from the "off-grid is based on loads" dictum.
    Were it me, I'd pick a couple of inexpensive golf cart batteries and a good pure sine inverter like the MS 300. I base this on the notion that my big inverter spends most of its time power less than 300 Watts. You could recharge off the generator to begin with, and add some panel when it becomes feasible. Since this would be "occasional use" power you wouldn't need the maximum panel to recharge, as there would be no load most of the time you're recharging. A couple of 135 Watt Kyoceras would probably do, with an inexpensive PWM controller around 20 Amps.

    Now if you plan to spin up a circular saw or table saw or band saw ... that's going to need much more than 300 Watts. You could run some of your equipment through a Kill-A-Watt meter and get an idea how much power it's going to use, although that won't capture the start-up surge.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Inverter????????

    For what it's worth, I just ran my 10" Skil tablesaw through my UPM meter. The saw is rated as 13A @ 120 VAC. The start-up was 4.9 Amps (118 Volts here). I pushed a piece of wood through it and loaded it fairly well: 8.6 Amps / 952 Watts. The UPM doesn't do Power Factor, but calculated it isn't good: 8.6 Amps * 118 Volts = 1015 Watts (this won't be entirely accurate). Still, something like the Exeltech 1100 Watt http://www.solar-electric.com/exxp12vol11w.html would probably handle it for occasional use.
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #9
    Re: Inverter????????
    Basically trying to do what was in my original post for a off grid shop
    You didn't specify what kind of shop, a wood shop would have different requirements from a metal shop with welders and such. If you just have a small wood shop, and plan on adding more panels, then you are already into a 24 volt battery bank. Below 1000 watts of panels, 12 volts will do, less then about 2000 watts, 24 volt will do, above 2000 watts, you will need a 48 volt battery bank. With your generator and a 4000 watt 24 volt PSW inverter/charger, you should have enough surge power to run most table saws, skill saw, drill press, joiner/planer, vacuum system and florescent shop lights with out them dimming too much. I would start with a four L16 batteries (420 amp hours @ 24 volts) using your generator to keep them charged when there is not enough solar or heavy usage. Don't consider cheaper MSW chargers to run motors, it will cause them to overheat and burn out. This is as small as I would start, if you are running welders, high horse power motors, even this will be too small. You will also need appropriate charge controller, fusing and wiring to put it all together.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Inverter????????

    Some more tool measurements:

    Small "pancake" compressor used to power air nailers: 12.4 Amps, and basically held peak from start-up (against pressure). 1372 Watts - sucked the line Voltage down from 118 to 112!

    6 gallon ShopVac: 6.5 Amps. 744 Watts.

    2.5 HP Skil circular saw: 8.3 Amps. 928 Watts (while cutting wood).

    Black & Decker reciprocating saw: 6.6 Amps. 750 Watts (while cutting wood).

    Those would be the big power consumers I've got around here at the moment.
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