Inverters

[cvick]

I am looking to build a small system of probably 2 x 100w solar panels (maybe 3 panels) to power mainly lights in a small off grid cabin. I will have roughly 10 led lights total. The only other addition I will have is a small water pump running on the system to pump water to a single toilet and single sink. I have decided to go with an inverter to convert solar to 120v AC throughout the system. My question pertains to the inverters themselves. It appears there are many styles, sizes and ratings with prices that vary as much as the models. It is a daunting market to determine what I need. I need something that would be easy to maintain with little maintenance/upkeep. I don

[cvick]

Message keeps getting cut off- last lines read:
......maintenance/upkeep. I don

[sensij]

Cut and pasting apostrophes doesn't work so well with the forum software. After you paste in your text, delete and retype them (and other puctuation like quotes, dashes, hyphens, etc)

[cvick]

I am looking to build a small system of probably 2 x 100w solar panels (maybe 3 panels) to power mainly lights in a small off grid cabin. I will have roughly 10 led lights total. The only other addition I will have is a small water pump running on the system to pump water to a single toilet and single sink. I have decided to go with an inverter to convert solar to 120v AC throughout the system. My question pertains to the inverters themselves. It appears there are many styles, sizes and ratings with prices that vary as much as the models. It is a daunting market to determine what I need. I need something that would be easy to maintain with little maintenance/upkeep. I dont need the top of the line, complex with all the bells and whistles. Simplicity and durability are key. Should I need to add a small refrigerator or very small TV later I would not want to be limited down the road. Any direction or ideas would be very much appreciated.

[SunEagle]

With only 200 to 300 watts of panels you will probably have a hard time running a TV and lights let alone adding a refrigerator.

With 300watts and a 30Amp MPPT CC you can charge a 250 to 300Ah 12volt battery system. That size system should handle a 600watt inverter.

Both Simplex and Xantrex make very nice inverters. To make sure you don't fry any electronics look at the True Sine Wave type and stay away from the modified Sine Wave which are cheaper but can hurt your loads.

You never mentioned the wattage of those 10 LED lights or that water pump. Knowing that and how long your plan on running your loads will help you properly size your battery and panel wattage. Under-sizing your battery and panel wattage usually leads to killing off your battery within a few months.

[cvick]

The refrigerator and TV are not part of the system. I just want to make sure if added down the road I would not be limited by the inverter purchased now. If added they would both be very small. My total actual wattage would be no more than 200-250 max with current system and would be closer to 40-80w standard/usage draw on the system on a standard basis as lights would be the only real draw. The This is a remote cabin and will only be used 6-8 days a month with 5-14 days between visits. The water pump would be a standard small water pump for pulling water from water catchment tank to toilet/sink. Nothing major or fancy.

I am just planning the system but was currently looking at two of the following batteries paired with 2 or possibly 3 100w panels.

https://www.amazon.com/ExpertPower-BLMFM12-200-XP-4D-Sealed-Battery/dp/B01GSZMJ86/ref=sr_1_1?ie=UTF8&qid=1500312918&sr=8-1&keywords=solar+battery+sealed+200amp

Thanks,|
VICK

[SunEagle]

The refrigerator and TV are not part of the system. I just want to make sure if added down the road I would not be limited by the inverter purchased now. If added they would both be very small. My total actual wattage would be no more than 200-250 max with current system and would be closer to 40-80w standard/usage draw on the system on a standard basis as lights would be the only real draw. The This is a remote cabin and will only be used 6-8 days a month with 5-14 days between visits. The water pump would be a standard small water pump for pulling water from water catchment tank to toilet/sink. Nothing major or fancy.

I am just planning the system but was currently looking at two of the following batteries paired with 2 or possibly 3 100w panels.

https://www.amazon.com/ExpertPower-BLMFM12-200-XP-4D-Sealed-Battery/dp/B01GSZMJ86/ref=sr_1_1?ie=UTF8&qid=1500312918&sr=8-1&keywords=solar+battery+sealed+200amp

Thanks,|
VICK

Ok you are focusing on a battery system which is very expensive. Also a single 220Ah battery needs about 22 Amps of charging which unless you have a MPPT type charge controller will be hard to get with only 3 x 100 watt panels. So what make and model CC do you have or plan to get?

Stop jumping to the battery until you determine your daily watt hour usage. So how many hours will you being using that 40-80watts each night?

I am not sure how many watts a "standard small water pump" draws but the words standard and small mean nothing. You need to find out the wattage of that pump and an estimated number of minutes or hours it will be used a day.

I am not trying to be a PIA. I am trying to make sure you don't spend hundreds of your dollars on something that won't work for you.

[Sunking]

The refrigerator and TV are not part of the system. I just want to make sure if added down the road I would not be limited by the inverter purchased now.

Thi si snot going to work out. Here is the deal. Panels, Batteries, Controller, and Inverter all have to be matched up to work with one another.

Lets work backwards and you will see the problems. A 12 volt 1000 watt Inverter requires at least a 12 volt 800 AH 500 pound battery. A 12 volt 800 AH battery requires 80 Amps of charge current. To generate 80 amps of charge current requires an 80 amp MPPT charge controller with a 1000 watt solar panel.

In a nutshell Inverter size should not be larger than the panel wattage. Now to make things even better, you would not want a 12 volt system for a 1000 watt Inverter. Why you ask, well it is too expensive and foolish. 1000 watts of panels requires a $700 80 Amp MPPT controller and some very large copper cables and fuses. That cost real money.

Smart money would be 24 volts. That same 1000 watt panel only requires a much less expensive 40 amp controller. At 48 volts only a 20 amp controller.

OK let me give you some tips. Forget 12 volt batteries, and 12 volt battery panels. Just get that crap out of your mind. 12 volt battery panels are low voltage and low power. They also cost 2 to 6 times more than higher voltage Grid Tied Panels like 200 to 300 watt panels. 200 and 250 watt panels are perfect building blocks. Using those will allow you to use MPPT controllers. Stay away from inexpensive PWM controllers. Lastly think 24 volts and forget 12 volts.

First thing you have top do is determine the full system and you do that by determining your maximum daily Watt Hour usage. If not you have a very expensive frustrating road ahead of you. You cannot do this in steps. You wil find the only thing you can reuse is the panels, and the rest has to be replaced.

If you must do it in steps. Determine what panels you will use. Say 200 watt panels you can buy today and 5 years from now. Get a good 40 to 45 Amp MPPT Controller that can do 12, 24, or 48 volt battery. With that you can start with a 12 volt system if you want. Then later you wil have to replace the batteries and Inverter with each upgrade. At 48 volts with a 40 amp controller will allow you to grow to 2000 watts. or 500 watts @ 12 volts or 1000 watts at 24 volts.

Before I forget, DO NOT BUY a prime number of panels except 1 or 3. The reason is with a prime number only gives you two options to configure your panels of all in Series and all in Parallel. Lat thing you want is parallel, and most controllers will allow to put up to 3 panels in series. 5, 7, 11 etc and you are screwed.

[cvick]

I will be using approximately 30-60w for approximately 5-8 hours on a single day 3-5 days out of a month. These days will be separated by 5 days to weeks before I will return to consume more power. I will have a total of 12 LED lights at 8w each, with no more than 5 on at any given time. If I flush a toilet a water pump will kick on and fill the toilet or if I wash dishes/turn on sink. Neither of which will have the pump running for more than 2-3 minutes at a time. We are talking a small on demand 110v water pump here. I am intending to convert everything, lights included to 120v- not 12v. I am not locked into ANYTHING at this point and am very much struggling to make heads or tales out of any of the suggestions on this board. Every time I think I have something figured out it is quickly dashed. It is very confusing with so much jargon which I am very unfamiliar with. Candlelight is sounding much more appealing at this point.... At any rate, I need to power the lights as noted and the pump as noted. That is it. Forget the refrigerator and TV were ever mentioned as that is something that is probably never going to occur. The only additional that I may have will be to charge a cell phone on occasion but not as a normal or a constant occurrence. Any additional power I need (tools etc.) will be powered from a standard generator.

Thanks,
VICK

[SunEagle]

I will be using approximately 30-60w for approximately 5-8 hours on a single day 3-5 days out of a month. These days will be separated by 5 days to weeks before I will return to consume more power. I will have a total of 12 LED lights at 8w each, with no more than 5 on at any given time. If I flush a toilet a water pump will kick on and fill the toilet or if I wash dishes/turn on sink. Neither of which will have the pump running for more than 2-3 minutes at a time. We are talking a small on demand 110v water pump here. I am intending to convert everything, lights included to 120v- not 12v. I am not locked into ANYTHING at this point and am very much struggling to make heads or tales out of any of the suggestions on this board. Every time I think I have something figured out it is quickly dashed. It is very confusing with so much jargon which I am very unfamiliar with. Candlelight is sounding much more appealing at this point.... At any rate, I need to power the lights as noted and the pump as noted. That is it. Forget the refrigerator and TV were ever mentioned as that is something that is probably never going to occur. The only additional that I may have will be to charge a cell phone on occasion but not as a normal or a constant occurrence. Any additional power I need (tools etc.) will be powered from a standard generator.

Thanks,
VICK

Ok. Lets say worst case of 60watt for 8 hours. That calculates to 480watt hours. To be conservative add in another 20 watt hours for the pump. That comes to 500 watt hours for a daily usage.

Figuring a 12volt battery and a 25% discharge you will need one rated about 170Ah (500wh / 12v / 25% = 167Ah}.

So a battery system similar to one of those 220Ah that you were looking at would be enough for your estimated load. And 300 watts of panels using a 30amp MPPT CC will generate enough charging amps.

Now you should be able to save some money using 2 x 6V 232Ah FLA Interstate batteries wired in series. They cost about $130 ea so for less than $300 you get a bigger battery then that single 12v 200Ah one you were looking at.

As I stated before you can find a Pure Sine Wave inverter made by Xantrex or Samlex rated 600 watts. I own a Xantrex Pro Watt 600 which is a really nice piece of equipment.

Now if you want to expand your system you will need more panel wattage and a bigger battery system. That 600w inverter should be enough to start a small 4 cu ft refrigerator but you need to keep an eye on the wattage so you don't over load the inverter.

Actually I just described my larger portable solar / battery system. The only difference is that I wasted money on a PWM CC which loses about 33% of my total panel wattage which meant I have about 400 watts of solar panels. Using an MPPT CC (while more expensive) is a better solution.

[Sunking]

Vick the issue is your story keeps changing. To do the small job you just spoke of is pretty easy and straightforward.Being part time means you can downsize the battery a bit.

Watt Hours = Watts x Hours

That is easy 5th grade math, but now look at what you just said 30 to 60 watts for 5 to 8 hours a day. Well that could be 30 watts x 5 hours = 150 watt hours, plus say another 100 for the water pump for 250 watt hours total. Or is it 60 watts x 8 hours a day = 480 Watt hours plus another hundred for the water pump for a total of 580 watt hours.

That is over 200% difference and that translates to 1 system using 150 watt panel with a 12 volt 100 AH battery, or a 400 watt panel system with a 12 volt 200 AH battery. See the problem? You have to nail down the daily watt hours first. Otherwise you are just pising in the wind. Always use the worse case.

Read this as it should help.

Tell you what, this will work for you

• Panel Wattage = 400 watts using 2 x 200 watt panels wired in series.
• Morningstar 45 Amp MPPT Controller good for 12 to 48 volt battery. Max power input 600 @ 12 volts, 1200 @ 24 volts, 2400 watts @ 48 volts. Lots of room to grow.
• 2 x US Battery or Trojan 6-volt 225 AH Golf cart batteries. The US Battery is a bit larger and less expensive.
• Samlex 600 watt 12 volt TSW Inverter.

[cvick]

Sunking- Please accept my apologies as I am very new to all of this and researching on the go, which means things change as I learn. I thank you for giving the breakdown above and the link. It has been very helpful! Ive gone back to the drawing board to insure that as you say I am not pissing in the wind. At any rate. This is what I have so far. I am going to install 14 total 10w LED 120v lights (actual number may be lower just insuring the worst case). This is 140w total and I am estimating worst case that I will burn them ALL for 7 hours in a day (neither are going to happen!). This is 980 watt hours. Now, add in the water pump which is 104 watts running less than 10-15 minutes a day (adding 1 hour worst case). 1084w x 1.25% (for losses) puts me at 1355 total watt hours. Now bearing this is mind, would a 24 volt system be more reasonable? If I installed 2 x 200w panels that if receiving 3 hours of sun per day (will get more), would generate 1200 watts correct? I know this is generating less than the 1355w, however, this was worst case scenario with overages in both directions. Would two 12v batteries now be needed to make 24v system? Also adding a larger 60amp charge controller? Please tell me I have grasped something with all of your help!!

Thanks!
VICK