How big of a system do I need?

[bartiks]

Hello all,
Quick question, we have a small cabin and we are wanting to put panels on it. Question I have is don't really know how big and how to run it, series or parallel. We will need something that we could potentially expand upon, but it won't get out of hand. I was thinking a 600W system but I'll let the experts here instruct me on what we will need.

Probably have a couple of lights, some flood lights around 3 of them. Potentially 3 fans and maybe a small fridge. All lights will be LED and the fans will be small ones. Potentially around 2' diameter. The fridge will be a small one like you had in college. Any advice would be greatly appreciated. Also if you all have a reputable site you get your supplies from please put that in as well. I know this question is very generalized, however I'm not for sure what we may or may not need.

[chrisski]

Really need an energy audit. With the devices you listed, the fans pull the most power and how long you have them on, and how big they are make a huge difference. The only fan I have is a 12” fan in my RV and I don’t like it leave that on. Anything that moves uses.more amps then the LED lights.


I may have put this link in your other post, but this will give you the correct way to size a system:
https://www.solarpaneltalk.com/forum...battery-design

[bob-n]

Chris is right about doing more math on your actual power usage.

LED: 10 watts when on
Mini Fridge: 700 watt-hours per day
Tabletop fan: 100 watts when on

If you don't have power lines to the cabin, then you need batteries. You size the batteries based on the amount of energy you need when the sun is down and to last through rainy and cloudy days, Then you size the panels to recharge the batteries when the sun is strong.

[Mike90250]

Mini Fridge: 700 watt-hours per day

Wow. That's about half of what I've seen. did someone give the mfg's religion ?

[bob-n]

I could be wrong, but I got that number from here:

https://homeguides.sfgate.com/much-electricity-mini-fridge-take-84594.html

"Compact refrigerators, typically ranging from 1.7 to 4.4 cubic feet, receive an Energy Star rating when they consume no more than 239.42 kilowatt-hours per year for manual defrost versions, or up to 318.4 kWH/year for units with partial automatic defrost."

[organic farmer]

In the 1980s we had a friend who lived by himself in a remote cabin. he had 400w of panels feeding a single battery. All he used it for was to power an FM radio.

[J.P.M.]

I could be wrong, but I got that number from here:

https://homeguides.sfgate.com/much-electricity-mini-fridge-take-84594.html

"Compact refrigerators, typically ranging from 1.7 to 4.4 cubic feet, receive an Energy Star rating when they consume no more than 239.42 kilowatt-hours per year for manual defrost versions, or up to 318.4 kWH/year for units with partial automatic defrost."

I sure don't know %ages on this, but not all products qualify for an energy star rating. On top of that, what %age of the Joe/Jane 6 pack's of the world will pay the likely extra up front $$ to buy an upscale fridge when the buy cheap, first cost syndrome is nearly ubiquitous ?

[bob-n]

Right. Some will buy junk or used refrigerators and waste energy.

bartiks is taking the time to ask questions and learn. I'm hoping that they will also think before buying a low-efficiency fridge.

[bcroe]

]we have a small cabin and we are wanting to put panels on it.

some flood lights around 3 of them.

I have 10 outdoor floodlights, but with motion detector activation, they are
almost always off, and the energy used is down in the noise. I think battery
types are now available. Bruce Roe

[MichaelK!]

At my own cabin, which has a standard 18cf refrigerator, full lighting, and a big-screen LCD TY, I'm consuming about 2.5-3.0kWh per day when nothing special is happening (like construction).

My life is not your life, but if you want to use that comparison, I'd say start with a 24V system with 1000-1500W of panels, 400-500Ah of battery storage, and a 5000W generator. That should get you through two days of cloudy weather before you need to start up the generator.

To save money, and barely squeak by, a minimalist system might be 24V with 750W of panels, 225Ah of golf-cart batteries, and still keep the same generator. I would not leave an un-attended refrigerator running on this system. But, it would keep the lights on while you are watching TV as long as it's not stormy.

My own 24V workshop system has 2000W of panels, a Midnight 200 controller, and a Conext 4024 inverter, with 568Ah of storage.

[J.P.M.]

Right. Some will buy junk or used refrigerators and waste energy.

bartiks is taking the time to ask questions and learn. I'm hoping that they will also think before buying a low-efficiency fridge.

If so, I'm pretty sure he'll also read my post and take it into consideration during his deliberations.

[bartiks]

Hi all and thank you for all the replies, I guess I could of provided you with a little bit more information on what the cabin will be used for. As it stands now we only go out there around every 2 or 3 weeks for probably 1/2 a day until temps warm up. So if I'm thinking about this right I don't think that I would really need a lot of panels to produce power like it's going to be used all the time. Granted the small fridge and the lights would draw power while we are not there. I was thinking we may need an "oversized" inverter along with some extra batteries to store the extra power until we do get out there and turn on a fan or 2.

Lots to think about here and as always thank you and keep giving this new guy some information to consider.

[Mike90250]

You do not want to "oversize" the inverter. Self-consumption is generally proportional to inverter size , however a name brand 1kw inverter is pretty much the minimum that can start a fridge compressor. And you dare not leave the fridge on while you are away, 3 cloudy days and the fridge drains the batteries.

[bartiks]

Well that is something to think about, thank you Mike. I can see how this could rather expensive rather quickly. Does anyone have a site they regularly visit for supplies and parts? I would like to check it out and start getting some pricing put together and see what the round about estimate would be. It does seem that I will need to up the array a little. thanks once again everyone.

[MichaelK!]

Well that is something to think about, thank you Mike. I can see how this could rather expensive rather quickly. Does anyone have a site they regularly visit for supplies and parts? I would like to check it out and start getting some pricing put together and see what the round about estimate would be. It does seem that I will need to up the array a little. thanks once again everyone.

Here's a company that I've bought from twice to buy the components for my systems. I've been happy with them so far.

https://ressupply.com/