Starter system for fridge

Hi, and welcome to the forum. I will get straight to it.

1. You are probably looking at more than $1,000 USD to do this.
2. Is this inverter a MSW or PSW? I don't think you are going to get a decent 3,000 watts PSW inverter for that amount of money. That is, IF that is even the size inverter you will actually need for your loads.
3. You have figured - IF the rating is accurate, how much your refrigerator uses per hour. You have to multiply the hourly use by about 14 hours or so, for actual watthours for real numbers. It's also best if you buy a power meter first, to verify your loads and run times. This would give you an accurate accounting of what your appliances actually draw, over 24 hours.



To save yourself the most money overall, start with the Kill-A-Watt meter, Then, determine your total loads. Then, you can go from there and start to calculate what you need to run said loads.

Let me see if I can offer you some good advice - from personal experience. Purchase reputable parts (solar modules, controller, batteries, etc.), rather than cheap made stuff. Trust me, I have done this first hand, and it cost me. Now, I ONLY use reliable, known brands of hardware.

I THINK the inverter is PSW, it's doesn't say but the next model down (1000w) is PSW. Although suspiciously costs almost as much, maybe I'll look further into that...

I do have access to a clamp meter and I do plan on doing some measuring as soon as I get the time.

As far as the batteries and panels, I do plan on buying from a reputable dealer and get something good. I have to try and save some money somewhere and the charge controller and inverter looked like a good place because I can upgrade later as I expand.


thanks

First modern fridges use about 1 Kwh per day, or a little more.

Next if you were going to use 12 volt it would require a 400 AH battery, and the last thing you want to do is use parallel batteries if it is not necessary, and it is never necessary for solar. Since there is no such thing as a 12 volt 400 AH battery will require you to use 6 volt batteries. However you would be much better off using a 24 volt system using 6 volt 200 AH batteries wired in series to give you 24 volts @ 200 AH.

OK minimum panel wattage to maintain a 24 volt 200 AH system is 450 watts using a 20 amp MPPT controller, or 600 watts using a cheap PWM controller like you selected.

A much less expensive set up for you would be:

2 x 225 Grid Tied Panels as they are much less expensive than battery panels about $450 to $500
Morningstar 20 amp MPPT Controller $200
4 Trojan T-105 6 volt 225 AH batteries $550
1 Kwh TSW Inverter $300

ok I looked up the Kill-a-watt meter, that's going to help! Way better that the clamp meter.

Sunking, I didn't realize there was a difference between panels used for off and on grid. Either way I think going on grid is going to complicate this whole project more than I want for now. Trying to keep it simple stupid until I get my feet wet a bit. And for the Batteries I was hoping to go AGM. less maintenance the better! And don't the flooded batteries give off fumes?

If I can't go large enough for my price point I'll just run different equipment off it until I can add on with more cells and panels. The fridge would be nice but I can start smaller...

The best Energy Star fridges use about 1KWh a day. Put it in your house and open the door 2x a day and you are looking at 1.5KWh So that's what you need to plan for. Since you don't plan to cycle the batteries daily, just 3 weeks a year, you can afford to go on the smaller size of battery bank (IMHO). But do all your failures happen with fair sunny weather ? Winter storms can be cloudy and give you no solar power (that's why I have 3 backup generators).

Starting surge measurements require a $200 meter, maybe you can have an electrician with one, measure your fridge for a fee (or a brew).

12V and parallel batteries is not going to work well. You need to go to a higher voltage, like 24V or 48V. Same amount of battery chemistry, but less losses with higher voltage.

3,000w inverter will waste power, since it's several times too large for your need. You want about 20% extra surge capacity of what the measured starting surge is. Say you measure 1300W for starting, and a 500w inverter can surge to 1200W. Won't work, but maybe a 600w inverter with 1800w surge for 5 sec, would do the trick. Going to have to read a lot of data sheets to find this.

The Kill-a-watt meter is good for measuring your total weekly/daily power usage, but it cannot measure the starting surge.

You want a pure sine inverter, mod sine will waste more power in heating the motor, than the pure sine wastes in overhead.

lots of good advice, you guys a great! Just to be clear, even though power outages are a huge factor in starting my setup I am still going to be cycling the batteries daily. I figure if I have the equipment I may as well use it and let it pay for itself. As far as power failures it's pretty random. I'm in NB Canada and typically the power has been fairly good for me. Prior to last week losing power for 7 days, the longest stretch was this winter for 12 hours. And prior to that rarely more than a couple hours at a time. But we get storms in any season that can knock out power. More often lately.


sounds like 4x 6v 200ah batteries in series is going to be a better bet. Is it safer this way too or just more efficient?

Huh. How does using Grid Tied panels on a battery system make it complicated? Battery panels cost twice as much as Grid Tied Panels. You can use Grid Tied panels on a battery system. Only catch is you have to use MPPT controllers.

What it boils down to is money and efficiency.

Wrong, dead wrong. Anything you take off grid will cost you 10 times more than buying it from the POCO.

Here in Asia, mains power and city water can be cut at any given time. So far, where I live, power only goes out about once per week. But, I do not run solar at my home. (I am considering a small array to keep my electronics running during power cuts, though. My UPS does not last long enough during the outages.)

At our farm, we run solar because we have no choice of mains. Of course, one thing I do like about solar, is it is clean, not noisy like a generator or wind power would be, and is reliable. (We have yet to have a power failure at our farm.) Mains power here, however, is unreliable, dirty, and is pretty expensive - in some areas up to .50c US / kWh. We pay almost .40c US / kWh, currently.


Higher voltage = lower ampere draws = smaller wires, therefore where you want to be - cheaper.
Batteries in series charge more evenly than batteries in parallel. So, series is more efficient.

With electric costs as high as .40c US/kWh a grid tie system would pay for itself pretty quickly. That is if your Utility allows grid tie systems.

Some people I know, who live in the southern part of this country are paying as much as .50c US / kWh.

I'm sure it would. Trouble is, IF the grid here allowed it, I wouldn't do it anyway. I don't want any part of my solar arrays attached to the mains in this country. The power grid here is just not reliable enough.

The Power went out several times during the day, yesterday.

It's a wonder that ANY electronics lasts ANY length of time, here.

I know the Philippines has recently started offering grid-tied systems to be attached to the mains. This has been approved for Manila and Cebu, so far. Not sure about other areas.

They also have duties and a limited supply system - controlled by the importer - similar to here.

We are at about 17 US cents/kWh but it is still cheaper than PV

Wow I guess I'm pretty lucky to be paying 10 cents per kwh (CDN)! And complaining about losing power only a couple times a year lol..

I'm starting to think my plan is a little silly now that I see most of you have a legitimate NEED for all the solar equipment with outrageous electricity prices, if you can even get it at all.. Maybe my money would be better spent on a silent diesel generator for my backup needs, that would run my whole house and not just the fridge.

I'm still going to build some sort of a small solar system, even just to keep the Net and wifi up and running in the event of smaller power outages.

Better than the diesel generator would be a LNG or LPG type. They are pretty common around here and with a 100 gallon tank you can run that generator for a long time. They also can be built into enclosures that reduce noise.