Solar PV panel Hot Water System

   / Solar PV panel Hot Water System #11  
Can't you design a solar water system that uses gravity or wouldn't that at least make pumping easy as in a small circ. pump that only draws >50 watts?
I have several circulation pumps in my radiant slab and one has a display that generally runs at 18w.
I'm very interested in summer solar domestic water. In the winter I pull it off the wood boiler.
 
   / Solar PV panel Hot Water System
  • Thread Starter
#12  
Can't you design a solar water system that uses gravity or wouldn't that at least make pumping easy as in a small circ. pump that only draws >50 watts?
I have several circulation pumps in my radiant slab and one has a display that generally runs at 18w.
I'm very interested in summer solar domestic water. In the winter I pull it off the wood boiler.
Hi,

If you heat water in winter off the wood fire, then making a solar hot water panel for sunny days is a good idea. I would think online resources would describe how. Getting fancy, you could run the pump on a small solar panel. Alternatively, if the top of the panel in below the top pipe on the tank, the heat will circulate the water automatically. Be warned that the hot water panels performance drops on windy days and once the sun is at more than 45degrees to the panel. Also there's no heating at all if there's cloud.

My PV panels are currently heating water for 2 people on overcast days, tho we're not in our winter yet, where the sun angle will reduce and so will output. The trick to getting performance on cloudy days was using panels suited to overcast conditions, and oversupplying the heating element. I connected 1000W panels to a 500W element. That way, on an overcast day where the panels performance drops to around 350W, the heating element still performs reasonably well. The elements don't care about being oversupplied when the sun comes out as the can only consume up to their maximum wattage, no matter what's supplied to them.
 
   / Solar PV panel Hot Water System #13  
Hi,

Thought I'd share an experience of converting a gas storage hot water system to be solar panel powered, without the need for an inverter or getting involved in high voltage AC. Being in Australia, some of the terms may be different, so forgive any confusion.

The LPG (Propane) gas fired storage hot water system I have uses around 0.3kg of gas a day, which is enough to be a worthy target in reducing my carbon footprint. I bought 3000W of "thin film" panels for $100. They make 60V and around 110W each. Of the 28 panels, I used 9. The thin film panels are superior for my situation, where we have many overcast days, and thin film perform well in the overcast conditions. The 9 panels makes 1000W in full sun, or about 350W on a bright overcast day.

The heating element is a 60V DC 500W immersion heater (eBay) on a 1/2" BSP thread. It is around 18 cm long and 15mm diameter. It's installed using the spare ports provided on the tank, with a 1" galvo pipe now running between the top and bottom spare ports. Using a T at the bottom of this pipe, the heating element is screwed into one side of the T to be running up the pipe. Convection moves the hot water up the pipe and into the tank. Make a sheet metal cover to avoid heat losses.

A DC 10a 60V thermostat is available on eBay. Use the DC fuse holders and switches from the recovered solar panels to save money on those.

Online calculators show the requirements for cabling. Solar panel connections from eBay.

Panels come in different voltages, and so do the heating elements. Elements are available in different wattages as well.

500W is heating enough water in a warm climate for 2 people.

The gas system remains in place, inactive because of the thermostat setting, for use in winter.

Next project: DC water pump to header tank using the remaining panels.

Happy days
Could you provide information on the solar panels you used? Thank you.
 
   / Solar PV panel Hot Water System #14  
I am thinking of getting a 2000 watt wind generator
from MO wind and solar and a 12 volt heating element
as I have an old hot water tank that I will put in my
shop to have hot water to wash etc. I have a small
hand crank washing machine so I can wash my shop
rags because my wife would have had kittens if I put
my greasy rags in the washing machine. I usually
go to the launder mat when I get a couple pails full.

willy
 
   / Solar PV panel Hot Water System #15  
I am thinking of getting a 2000 watt wind generator
from MO wind and solar and a 12 volt heating element
as I have an old hot water tank that I will put in my
shop to have hot water to wash etc. I have a small
hand crank washing machine so I can wash my shop
rags because my wife would have had kittens if I put
my greasy rags in the washing machine. I usually
go to the launder mat when I get a couple pails full.

willy
Small wind turbine facts, efficiency and expectations, please read this before thinking about installing a wind turbine.


These people have been in the Renewable Energy business for over 10 years and are a competent source of information.
 
   / Solar PV panel Hot Water System #16  
What controls do you have in place to prevent OVER heating the water?
 
   / Solar PV panel Hot Water System
  • Thread Starter
#17  
Could you provide information on the solar panels you used? Thank you.
Hi,
The brand is Kaneka and they're thin film silicon which is the type needed for improved output in overcast conditions compared to regular panels. They produce 60V, which is unusual but handy as that reduces the amperage required. Beware of the danger of this voltage and that laws may require an electrician for that voltage.
 
   / Solar PV panel Hot Water System
  • Thread Starter
#18  
What controls do you have in place to prevent OVER heating the water?
Hi,
I have an electronic thermostat set to cut the supply of electricity at a temperature of 160F/70C. I found it on eBay and it's 60v/10A DC.
 
   / Solar PV panel Hot Water System
  • Thread Starter
#19  
Hi,
Just discovered that the thermostat won't reboot on its own in the morning as the sun rises. I suspect it can't cope with the variable voltage and amperage that occurs as the panels are progressively struck by sunlight. I'll have to find a work around.
 
   / Solar PV panel Hot Water System #20  
Hi,
The brand is Kaneka and they're thin film silicon which is the type needed for improved output in overcast conditions compared to regular panels. They produce 60V, which is unusual but handy as that reduces the amperage required. Beware of the danger of this voltage and that laws may require an electrician for that voltage.
Thank you,
Jim
 
 
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