# learning about converting solar to 110 volts



## budgetprepp-n

Hi everyone,
As some of you know I did a post on Installing my first solar system. I kept it all 12 volts to keep
things simple. since then I have been experimenting with an inverter and every kind of 110 volt bulb
that I could get my hands on. I was really surprised at how long I can get a 110 volt bulb to run on
one 12 battery. So I'm thinking that I might add a little to the system and run some regular house
lights, computer, TV, and get the set up ready for a super efficient refrigerator that I might pick up
later. Now this might be a month or so before I even get started and I will do another post on this 
project. (I want to get an independent water system done before I start this project)
Also I think I have found a way to pump the water out of my well and eliminate the storage for
huge drinking water using the solar setup. 
So,, I would like to know would there be any interest in a post like this?
And if you have any questions or ideas on this it would be great to get some input and ideas now
I plan on tying in to the existing wiring at the fuse box and some help might be needed there.

And I just got a killer deal on two 235 watt solar panels they are for grid tie in but I have been spending
some time reading and talk to some experts on the phone and if it is done right with the correct inverter
they could be converted into two really strong off grid panels so I'm even thinking of setting them up as a 
separate system for the heavy stuff. - just Kicking around some different ideas for now--
That's where you guys come on,,,, The appreciate all the ideas and help on the past project

Questions or input?


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## Prepadoodle

Running regular bulbs is generally not a great idea. It's always better (cheaper & easier) to reduce consumption rather than just add more PV. 

A 60 watt incandescent bulb obviously uses 60w, and wastes most of the power as heat. A compact fluorescent that puts out the same amount of light will use about 13w, and an LED light will use as little as 7w for the same light output. The LED light will also last for more than 20 years.

Anyway, I think having 110 AC is a good plan, even though you lose a few % in the inverter. I for one would be interested in reading about your project.


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## PalmettoTree

Remember the formula: watts equal volts times amps

With this you should be able to get some ballpark capability. Remember all components have resistance therefore using the above calculation will be your upper limit but not achievable when used on large numbers of components in your circuit.


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## budgetprepp-n

Prepadoodle said:


> Running regular bulbs is generally not a great idea. It's always better (cheaper & easier) to reduce consumption rather than just add more PV.
> 
> A 60 watt incandescent bulb obviously uses 60w, and wastes most of the power as heat. A compact fluorescent that puts out the same amount of light will use about 13w, and an LED light will use as little as 7w for the same light output. The LED light will also last for more than 20 years.
> 
> Anyway, I think having 110 AC is a good plan, even though you lose a few % in the inverter. I for one would be interested in reading about your project.


Hi And thanks for your input,, Ok I have been reading and I see the same thing you are telling me.
But this is what I did I tried those energy saving bulbs from more than one place and some use more juice 
than others even if they say the same on the box. I can start with just one battery and use an inverter and
run one bulb that is as bright as a regular 75 watt for 11 hours. Ands thats starting at 13.5 volts and only going down to 12.6 I found that quite surprising and impressive. My battery is a walmart [email protected] 12 volt deep cycle.
The inverter and bulb only pulls 1.2 amps that should be 144 hrs divide by 1.2 =more that I thought


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## budgetprepp-n

Thanks and I have a request,, Can you post some more formulas? 
I writing them down this time. Thanks for your help 
"And thank you for not speaking techanize"


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## Prepadoodle

The most important equation here would be P=IE, where Power (in watts) equals Current (in amps) times Voltage (in volts). From this, we can get I=P/E, which is saying that the amperage will be the wattage divided by the voltage. For example, a 100 watt bulb running at 100 volts will draw 1 amp.

The easiest way to see the savings is to look at it like this... if you are paying $1 per watt for panels, you would spend $60 to power a 60watt incandescent bulb. If you were using LED lighting and could get the same light output for 7watts, you would spend $7 for the panel, which is a savings of $53. The incandescent bulb costs $1 and the LED bulb costs $14, so the total of bulb and panel would be $61 (60+1) for the incandescent and $21 (7+14) for the LED.... roughly 1/3 of the cost.

But that's not the total picture. The incandescent bulb will need to be replaced about 20 times to match the life of the LED bulb. The incandescent will need more PV, so more mounting hardware, a bigger inverter, more batteries, and so on. In the end, it's not even close... go with the LED lighting.

The one thing that seems to be missing from your calculations is the amount of discharge on your batteries. You don't want to run them right down to nothing. If you want no more than a 25% discharge (fairly typical) and your battery is 114 amp/hours, you would be getting just over 28 hours of use at a 1.2 amp draw.

The cheapest place I have seen solar and wind equipment is at Northern Arizona Wind & Sun, where you can buy the solar panels for less than $1 per watt. I will be going with the SolarWorld SW-250 panels at about $1.10 per watt or the SW-265 at about $1.20 per watt because I like their guarantee. (they guarantee less than 0.7% drop in output per year for 25 years)

This is an interesting thread, please keep us posted!


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## LunaticFringeInc

Please post any "real world" experiences you have with this project or any other related projects.


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## paraquack

One of the biggest mistakes made by people putting an inverter into a system is forgetting that it takes 10 times the amps out of the battery to go into the inverter compared to the amps on the label of the device being powered (actually a tad more). Example: you want to run a 120 volt fan, listed amps on the label is 1.3 amps; because the battery voltage is 10 times less (12 volt vs. 120 volts) the amperage consumed by the inverter is 13 amps (plus a little more for the inefficiency of the inverter). Years ago, before CPAP machines for people who have sleep apnea when they sleep, didn't operate on 12 volts DC, only 120 volts AC. A friend who tented with his boys every year a Boy Scouts wanted a way to run his CPAP in the tent. I went thru the whole explanation with him. When he went to Batteries Plus to buy the inverter and battery, the guy made the mistake above and sold him a small battery rated for 12 amps. He tried it out and over course it worked fine for the 5 minute test, but when he actually needed it, it ran for an hour and quit. He called me and gave me the data from the CPAP and I told him to buy a full size RV battery. Everything was fine then.


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## budgetprepp-n

I hear what you are saying in every room I have SMD or LED bulbs in overhead fixtures. 
They use next to nothing far as amp draw goes but I must confess that while they do the 
job they just are not as a comfortable light as a standard bulb. The solar set I have seems
to have more juice in the batteries than I am using and I plan on adding another battery so
why not use it? If I run my lights a lot during the night by 11 or 1 o'clock the batteries are back up 
to full charge. I can run two or three of the energy smart bulbs with a converter off of just the panels during
the day and not affect the charge in the batteries so why not use it? I meen I run a couple of
lights during the day just to keep the house from being too dark inside. 
Right now I don't have a working amp draw gauge on my MPPT control box (sent back for warranty)
But what it takes to power one or two of the smart bulbs is not much. 
I have a kill-a-watt meter and I'm ordering a lumens meter when I get everything I need I'll run some test
and compare what it takes to run the bulb --watts and amps--from house current and then see what it 
takes to run it from a battery. Maybe it does take 10 times more power to run it that way. 
And the inverter I am using right now is just an inverter I hope to soon have a "pure sine wave"
inverter I'm told they are a lot more efficient than a standard inverter.-we will see about that too- 

The setup I have has got is all I will need when TSHTF. now I'm just tweaking it and seeing how far I can 
take it. If I can run some lights, TV, computer, and other small stuff with a small investment why not?


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## budgetprepp-n

----------------My findings so far---real world ---------------------------------------
Don't take this the wrong way I'm not here to argue or disagree with anyone I'm here to learn and share what
I find and learn,, My findings so far,,,,,,,,,,,,,
I had used a GE energy smart bulb 825 lumens (a little brighter than a standard 60 watt bulb) warm soft light #32700k 
I ran the inverter from the control box rather than straight off the batteries to get a accurate reading on the amps.

On house current it pulled 13 Watts for just the bulb---------- 13 watts -divided by- volts 110 = .12 amps
Using the inverter and battery it pulled 1.4 amps.-------------- 1.4 amps x 12 volts= 16.8 watts 

someone let me know if these formulas are correct------ So,,yea you're right about 10 times the amps 
if the amps jumped up 10 times why didn't the watts go up as much? Or are my formulas incorrect?


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## HuntingHawk

The difference is the loss in the inverter. Some are more efficient then others. Ideally, 12VDC converted to 120VAC takes 10X power.

Solar panels don't care if their use is on or off grid. Its the inverter that determines on or off grid.

And you run into another issue with larger panels. Say you have a 200watt panel that is 24volts. A 100watt panel 12volts would produce about the same amperage.


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## Prepadoodle

Your numbers seem about right to me. A watt is a watt, it doesn't matter where the power comes from. If you were on 120V main power, it will pull 1/10th the amps as the same bulb on a 12V battery because a watt is an amp times a volt. If one goes down, the other has to go up because the power stays the same.

120V X .1 amps is the same as 12V X 1 amp... 12 watts. Yeah, the current is 10X more with the 12V battery, but the voltage is 1/10th as high, so the power is the same.

If the bulb pulled 13 watts on house current and 16.8 watts with the battery and inverter, the difference is due to the inefficiency of the inverter, and the numbers seem to be in the ballpark to me. Your inverter probably also has at least an LED indicator light on it, this is using a little power too, and your ammeter is eating a little bit too. There's no such thing as a free lunch.

The GE Energy Smart bulbs are LED technology, and a good (but not the least expensive) bulb to use for solar applications.

I also agree that if you have the power, you might as well use it, but you did indicate that you were going to be adding refrigeration and maybe water pumping to your solar loads. Bottom line, it's always cheaper to conserve rather than add more batteries or panels.

By the way, although I do have a degree in electronics, I am not claiming to be an expert on batteries. As I understand it, the number of amp/hours in a battery depends in part on the discharge rate. As an example, the Trojan L-16RE-A is rated at 352 AH at a 20 hour rate and 360 AH at a 100 hour rate. This basically means you get more total power out of your batteries when you draw the power out more slowly.


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## Prepadoodle

HuntingHawk said:


> ... And you run into another issue with larger panels. Say you have a 200watt panel that is 24volts. A 100watt panel 12volts would produce about the same amperage.


Right, because P=IE. To isolate the "I" (current, in amps) divide both sides by E; P/E=IE/E; the "Es" on the right cancel each other, so I=P/E meaning an amp is a watt divided by a volt.

So 200w/24v=8.33 amps, and 100w/12v=8.33 amps. At the same amperage, twice the voltage means twice the power.


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## budgetprepp-n

Question about inverters,,, I been reading and watching videos about inverters and I see that there are
two main kinds. The standard modified inverter and the "Pure Sine Wave" inverter.

From what I have learned solid state electric motors (like in variable speed drills or fans) TVs, Computers, and 
most electronics don't work well with the standard inverter. In more than one video using the standard inverter 
I saw some of the motors made a buzzing noise and pulled more current. With the pure sine wave they ran smooth and
more efficient.

Has anyone ever used both to see what the difference was? 

Also they come in all kinds of sizes 300 watt to 10,000 watt I was thinking of going with a 1500 watt
from what I have seen the smaller inverters use less than 1 amp to operate 
Or has anyone have any input on the inverter information?


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## Prepadoodle

Northern Arizona Wind & Sun's site has a good basic solar information site located at: windsun.com. They have an "Inverter Selection" page that walks you through all the different kinds of inverters and which are best for which application. Rather than just repeat what they say, (which is good, solid info), here's a link to that page... Inverter Selection


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## PalmettoTree

Pure sine wave inverts convert DC to AC with a sine curve. Do a search on "occilloscope and AC current."


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## HuntingHawk

Pure sine wave inverter is always the best choice but also the more expensive. What you are going to run & duration dictates if you need pure sine wave or if modified is sufficient.

I happen to have a pure sine wave of 2,000watts as the primary 120VAC of my solar system. But also have a 1500watt modified sine wave. When I started out, I was given the advice that if it had a motor to use a pure sine wave but a modified is fine for everything else.

I've 120VAC angle grinders & they should be operated on pure sine wave but will operate on modified which I can tell they don't operate as well. However, I have an 18VDC cordless angle grinder & using modified for the battery charge is just fine as is charging the bateries for any of the Dewalt cordless tools I have.


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## budgetprepp-n

Then I think I will just go with the pure sine wave,, It'd hard to tell what I might be running.
For now a computer, TV, along with a few lights. The inverter I have now is a yard sale 800 watt
I'll keep it as a backup for the lights


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## budgetprepp-n

Another question about inverters,,,, 
The inverter I used for testing stuff is a 800 watt and by itself with no load it didn't
take hardly any power to run. And I'm told that a 1000 or 1500 watt is the same way
anyone know for sure if this is true? I would spend a little extra and get one a little
bigger just in case I need it later if I knew it wasn't going to suck up too much electric.


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## Montana Rancher

They only draw as much current as you use + some basic power draw for the inverter so 1000 watts will draw the same from the battery with either a 1500 or a 4000 watt inverter.

The larger inverter may actually draw less amps


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## budgetprepp-n

And still yet another question,, I been bidding on inverters on eBay hoping to get a good deal and I have noticed
that some are 12 volt to 220 volt. My question is would it be easy to get 110 volts from the 220 supplied
by the inverter? I mean when it comes in the house off the grid that's 220 and getting 110 is no problem
would this be the same?


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## HuntingHawk

NO.

I would explain but its technical. 240 to a house is a common wire with two legs of 120VAC each. So you can tap onto one leg to get 120VAC.


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## budgetprepp-n

HuntingHawk said:


> NO.
> 
> I would explain but its technical. 240 to a house is a common wire with two legs of 120VAC each. So you can tap onto one leg to get 120VAC.


Just NO? ,,,,,,Ok straightforward,, Thanks for not speaking techaneez
So a 12 volt to 220 inverter is a committed 220 volt. If I would like to have 110 and 220 volt I would need two converters?


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## HuntingHawk

Converter does AC to DC. Why a converter?


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## budgetprepp-n

HuntingHawk said:


> Converter does AC to DC. Why a converter?


 Opps I meant I would need two "INVERTERS" if I want 110 as well as 220 ?
<--- looks down and kicks a stone


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## Montana Rancher

budgetprepp-n said:


> Just NO? ,,,,,,Ok straightforward,, Thanks for not speaking techaneez
> So a 12 volt to 220 inverter is a committed 220 volt. If I would like to have 110 and 220 volt I would need two converters?


No you are wrong

Think of it this way...

ALL of your power comes in as 240v to your breaker box

If you examine your breaker box you will see 1x line of 120v PLUS 1x line of 120v and a common (ground)

If you need to run an appliance on 120v you hook it to ONE SIDE of the feed

If you need to run a 240V appliance you hook it to BOTH sides of the feed

So a 240W Inverter can supply BOTH 240v and 120V as you can split off half of the 240 to supply the 120

Clear as mud?


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## HuntingHawk

Montana Rancher said:


> No you are wrong
> 
> Think of it this way...
> 
> ALL of your power comes in as 240v to your breaker box
> 
> If you examine your breaker box you will see 1x line of 120v PLUS 1x line of 120v and a common (ground)
> 
> If you need to run an appliance on 120v you hook it to ONE SIDE of the feed
> 
> If you need to run a 240V appliance you hook it to BOTH sides of the feed
> 
> So a 240W Inverter can supply BOTH 240v and 120V as you can split off half of the 240 to supply the 120
> 
> Clear as mud?


That's what I said, two legs of 120VAC each.


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## HuntingHawk

Simply put, if you want 120VAC from 12VDC get the proper inverter for the size you need. 

If you want 240VAC from 12VDC (or 24VDC or 48VDC) get the proper inverter for it.

But there is a serious issue with 240VAC inverters when using with motors as you need the phases syncronized or motor will burn up.


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## Montana Rancher

HuntingHawk said:


> That's what I said, two legs of 120VAC each.


Hey
I didn't say YOU were wrong I said buggetpreppn was wrong, a 240v inverter can do BOTH 120 and 240v


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## budgetprepp-n

LOL If you look almost everything I said has a question mark right after it I don't know beans about
Getting 240 volts and 120 volts from an inverter. I know how it works when it comes in from the grid
but using an inverter is a whole nother world. I'm here trying to learn.
And I must admit so far I have picked up some knowledge from this thread.


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## HuntingHawk

Be very careful of anything marked as 220VAC as it will probably be 50 cycle which is not what you want for any US products. Everything used in the US is 60 cycle(cps).

BTW, you mostly state 110VAC. Commercial power coming into a house each leg should be 113-117VAC. 113VAC is low limit voltage for many items. That is why its referred to as 120VAC.


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## PaulS

Keep in mind your "start-up" amperage. TVs can use up to 10 times there "rated" amps or watts when they start up. Motors do the same. Even your computer uses more power on start-up than it does just running. If you have a computer with a 200 watt power supply you may need a 2000 watt inverter to run it.


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## budgetprepp-n

PaulS said:


> Keep in mind your "start-up" amperage. TVs can use up to 10 times there "rated" amps or watts when they start up. Motors do the same. Even your computer uses more power on start-up than it does just running. If you have a computer with a 200 watt power supply you may need a 2000 watt inverter to run it.


I have seen and read many times about how a TV will have a huge surge, But is that the old ones?
I did mine with a kill-a-watt meter and it took about 90 watts when I first turned it on then settled in at about 40 watts


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## HuntingHawk

Yes, that is with the old tube type. Same for old style computer monitor. Flat screen TVs & monitors don't require that surge power.


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## PaulS

Yes, the newer TVs are better but they have a power supply just like your computer and that big transformer has a start-up demand too. It isn't as bad as the tube style because the power supply is smaller and the electronics consume less power. The power supply is what requires the large start-up current. (in your case about 225% of rated watts)


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## Prepadoodle

That's why all inverters list a surge rating and a continuous rating. Inverters are designed to handle start up surges for a short period. You don't need a 2000 watt inverter to power a 200w power supply.


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## exmilitary

budgetprepp-n said:


> ----------------My findings so far---real world ---------------------------------------
> Don't take this the wrong way I'm not here to argue or disagree with anyone I'm here to learn and share what
> I find and learn,, My findings so far,,,,,,,,,,,,,
> I had used a GE energy smart bulb 825 lumens (a little brighter than a standard 60 watt bulb) warm soft light #32700k
> I ran the inverter from the control box rather than straight off the batteries to get a accurate reading on the amps.
> 
> On house current it pulled 13 Watts for just the bulb---------- 13 watts -divided by- volts 110 = .12 amps
> Using the inverter and battery it pulled 1.4 amps.-------------- 1.4 amps x 12 volts= 16.8 watts
> 
> someone let me know if these formulas are correct------ So,,yea you're right about 10 times the amps
> if the amps jumped up 10 times why didn't the watts go up as much? Or are my formulas incorrect?


Yes this formula is right for a square wave inverter. For a sine wave inverter it might change due to that fact that a square wave inverter is hard on equipment, due to its pulsing square waves, where the sine wave in more soft waves thus less hard on equipment.

I have seen alot of equipment get damaged from a square wave inverter but the equipment is not made for it.


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## PaulS

The inverter has losses so when you run the inverter off batteries the batteries have to power the inverter and the light. Check the draw at the light with an ammeter both ways and you will find the draw of the light is closer. The inverter will likely be more efficient running line voltage than at 12 vdc as well. 
The large surge that I was discussing earlier is for accessories that have coils and transformers in them. An electric motor takes time to get up to speed. During that time (and under high loads) it will draw many more amps that it does once it is running at speed. Your 10 amp electric drill may require 100 amps to get up to speed where it will run happily on just 10 amps. If you are drilling a one inch hole with that drill the power consumption will go back up as the load increases. Most lights (well incandescent lights) you can calculate the power requirements by using the listed wattage. With LED and Fluorescent lights you have to keep in mind that they have transformers that will require a higher amperage while starting than when they run. (neither fluorescent lights or LED lights should be run on a modified wave inverter)


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