Running dehumidifier/heater through solar panels

May A

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Aug 5, 2022
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Hi All, and thank you for opportunity to ask questions. Though I will contribute my experience later on. I am non-native English speaker but I know you all are smart guys to understand what I mean.

I would like to run my dehumidifier (170watt) and small electric heater panel (300watt) through solar panel during the day and solar panels will be fitted in my garden. In a sunny day I have around 6 hours of direct sunlight in my garden in winter. I live in UK so considering mostly cloudy weather I need some advice.

I don’t need battery as I want these units work only in the day to warm up my daughter’s room (around 12 sqm) and keep dehumidifier clear the air. So not saving from electricity bill but keep the room warm in the day is initial target.

I decided to buy 2x JA Solar JAM54S30-405/MR panels. Very affordable prices around £180 per panel (at least it’s good for me)
Specifications:
  • Mono cells
  • No. of cells: 108 (6 x 18)
  • Rated max. power: 405W
  • Cable cross section size: 4mm² (IEC), 12 AWG (UL)
  • 11 BB Perc Cells
Do you think 2 of this panels enough to power total 460watt units in a cloudy day? It’s not always cloudy in south UK but mostly it is.
What kind of inverter I need? What kind of controller you recommend? Shall I buy 1 more solar panel? I am asking these because I don’t want to buy a controller or inverter which is more capable then what it’s required.
I don’t understand technical readings but I am very much able to trim/extend cables, run them through house using trunking and junction boxes doing neat job (master of using drill machines and making deep holes carefully not touching wires and pipes and seal them).
Is it doable?
Thank you for your time reading. I will take pictures and write my exprience later.
 
Last edited:
Hi All, and thank you for opportunity to ask questions. Though I will contribute my experience later on. I am non-native English speaker but I know you all are smart guys to understand what I mean.

I would like to run my dehumidifier (170watt) and small electric heater panel (300watt) through solar panel during the day and solar panels will be fitted in my garden. In a sunny day I have around 6 hours of direct sunlight in my garden in winter. I live in UK so considering mostly cloudy weather I need some advice.

I don’t need battery as I want these units work only in the day to warm up my daughter’s room (around 12 sqm) and keep dehumidifier clear the air. So not saving from electricity bill but keep the room warm in the day is initial target.

I decided to buy 2x JA Solar JAM54S30-405/MR panels. Very affordable prices around £180 per panel (at least it’s good for me)
Specifications:
  • Mono cells
  • No. of cells: 108 (6 x 18)
  • Rated max. power: 405W
  • Cable cross section size: 4mm² (IEC), 12 AWG (UL)
  • 11 BB Perc Cells
Do you think 2 of this panels enough to power total 460watt units in a cloudy day? It’s not always cloudy in south UK but mostly it is.
What kind of inverter I need? What kind of controller you recommend? Shall I buy 1 more solar panel? I am asking these because I don’t want to buy a controller or inverter which is more capable then what it’s required.
I don’t understand technical readings but I am very much able to trim/extend cables, run them through house using trunking and junction boxes doing neat job (master of using drill machines and making deep holes carefully not touching wires and pipes and seal them).
Is it doable?
Thank you for your time reading. I will take pictures and write my exprience later.
I can’t speak for the uk directly but I live in the north east USA and in my application I can expect about 1/4 of the panel’s rating on a average cloudy day 1/8 or less on a heavy overcast day. If you normally have any kind of variation of the amount of cloud cover that you have a battery will be helpful as most of the day you will be producing more power (power wasted) or less power than you need (devices not working). All in one solar inverters are made that will work on solar only for the US market I expect they have some for the UK also.

If I was going to try you idea this is how I would calculate it

460w load
405 watt panel x .25 expected output 100w x .80 controller and inverter efficiency losses 80w

460 / 80 = 6 panels

That’s just barely making it. In winter the output might be less. Whenever you just barely don’t have enough solar your entire system will shutdown. If you were to add a 100ah lifepo4 battery into the picture and if any of your devices cycle on and of the amount of available energy will expand drastically.
 
One very important point is that the solar panels you are looking at produce DC current, whereas I'm assuming the heater and dehumidifier you want to run are standard 230V 50Hz AC? That seriously increases the level of complexity of the system you want to design. Doable, yes. Doable on a tight budget, no. At the very least, you will need battery storage, and an inverter to convert DC battery power into AC house current.

From my personal experience, on rainy days, I see about 10% of normal output from my panels, so to power a 460W load, you basically need ~4600W of panels. That is NOT going to be cheap. It is also going to take up a LOT of space. On rainy days at my cabin, with 5500W of panels online, I'm seeing 500-600W. So these numbers are coming from real-world production.

So, we are talking about scaling up what you originally envisioned by a factor of 5 fold, and this is going to cost thousands of £. It that something you are prepared for?
 
Thank you for your replies. I really appreciate it. My plan and budget is limited to £1000. Actually investing on lifepo4 battery would require on another budget which I can make it later on.
In the light of your comments I decided to buy 2 solar panels and run only dehumidifier which is consuming only 156watt per hour. I am really curious how much electricity 2 405watt solar panel will produce on ordinary cloudy day and will do expansion accordingly.
I can put up maximum 5 panels. I will use a sine wave inverter and mppt controller. I will send results at the end of this month after holiday.
 
Thank you for your replies. I really appreciate it. My plan and budget is limited to £1000. Actually investing on lifepo4 battery would require on another budget which I can make it later on.
In the light of your comments I decided to buy 2 solar panels and run only dehumidifier which is consuming only 156watt per hour. I am really curious how much electricity 2 405watt solar panel will produce on ordinary cloudy day and will do expansion accordingly.
I can put up maximum 5 panels. I will use a sine wave inverter and mppt controller. I will send results at the end of this month after holiday.
Nothing like real world data to determine what your location will need. Enjoy the process it’s a lot of fun.
 
Hi May A,

I am curious what dehumidifier you have. Mine consumes substantially more than 156 watts, and the most efficient one I could find was still in the neighborhood of 300 watts.

Thanks.
 
Thank you for your replies. I really appreciate it. My plan and budget is limited to £1000. Actually investing on lifepo4 battery would require on another budget which I can make it later on.
In the light of your comments I decided to buy 2 solar panels and run only dehumidifier which is consuming only 156watt per hour. I am really curious how much electricity 2 405watt solar panel will produce on ordinary cloudy day and will do expansion accordingly.
I can put up maximum 5 panels. I will use a sine wave inverter and mppt controller. I will send results at the end of this month after holiday.
Would be nice once this project is built to post parts and costs.

I also recommend you plug the dehumidifier into a kilawatt meter to figure daily ussage. In my part of the world, the most humid time of year iis now, so that is a good time for me.

Very important to take that data of kWh per day to see if your system is right sized with an approriate battery pack. For where I’m at, I like to have enough power to get though a cloudy day, so twice the daily kWh. For the battery pack, lead acid needs to be at least twice this number to avoid going under 50% and hurting them.

Once you figure out the wWh requirement, you can run it through the solar calcualator I have linked to see how many panels are required for watt hours.

I‘m hard pressed to see a way this would be cost effective. With all the cloudy days, there’d need to be a way to shut the system off. If needed, you;d still need a way to power the dehumidifier. That could be a lot of work to save a few pennies in electricity per day.
 
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