diy solar

diy solar

24V solar system for a well

JamesHird

New Member
Joined
Jan 10, 2022
Messages
40
Hello everyone. I’m looking for advise on the best way to set my system up.

I’ll try and give as detailed description as possible about the system I am currently building for the well.

I’ll be using a 24v low flow rate pump (3GPM) to pump the water into a 275 gallon tank at the head of the well.
The well is 140’ with a static water level of 20’. It produces 30+ GPM


This is the pump


Using online voltage drop calculators I can set this pump at 70’ down the well using #10 wire with a allowable voltage drop of 3%.

I’ve got the renogy 40a charge controller, 4x renogy 100w solar panels and a couple of 12v lead acid deep cycle batteries

I’m going to set the solar panels up 2s2p to have a VOC of 48.6v and a Isc of 10.42a. The maximum draw of all the loads should be around 9-10 amps.

The loads will be, the pump, a 24v extractor fan, lights and a low voltage heat pad controlled by a thermostat for when it gets really cold.

This is the extractor fan


The tank has two electric float sensors (didn’t trust just one) that trigger a normally closed relay controlling the pump.

I only want the pump and the extractor fan to run when the solar panels are producing enough to power them without the aid of the battery.

I need the batteries to be fully charged and the heat pad needs to be able to come on at any time.

Can anyone help me with the best way to do this?

Thanks in advance.
 
From my little bit of knowledge, you will need a 24v fuse box, like the kind you get in a truck. Does the Renogy charger have a load output? Think it'll all need to be wired up to that through the fuse box.

I'm not sure how you would program the Renogy to only use solar to power the load output tho (I'm an AIO and victron user) and charge the batteries. Unless you can get a light sensor to switch between battery & solar.
 
Hello everyone. I’m looking for advise on the best way to set my system up.

I’ll try and give as detailed description as possible about the system I am currently building for the well.

I’ll be using a 24v low flow rate pump (3GPM) to pump the water into a 275 gallon tank at the head of the well.
The well is 140’ with a static water level of 20’. It produces 30+ GPM


This is the pump


Using online voltage drop calculators I can set this pump at 70’ down the well using #10 wire with a allowable voltage drop of 3%.

I’ve got the renogy 40a charge controller, 4x renogy 100w solar panels and a couple of 12v lead acid deep cycle batteries

I’m going to set the solar panels up 2s2p to have a VOC of 48.6v and a Isc of 10.42a. The maximum draw of all the loads should be around 9-10 amps.

The loads will be, the pump, a 24v extractor fan, lights and a low voltage heat pad controlled by a thermostat for when it gets really cold.

This is the extractor fan


The tank has two electric float sensors (didn’t trust just one) that trigger a normally closed relay controlling the pump.

I only want the pump and the extractor fan to run when the solar panels are producing enough to power them without the aid of the battery.

I need the batteries to be fully charged and the heat pad needs to be able to come on at any time.

Can anyone help me with the best way to do this?

Thanks in advance.
what is the air pump for? It uses 3 amps according to Amazon. That’s almost 75watts. If you are running it 24 hours a day your setup won’t even run that one device. If you really want to only have the pump work when you have sufficient solar the simplest and probably cheapest thing to do is to is to purchase the recommended spec 200w solar panel for the pump and run it separately from the rest of your system. You will produce noticeably less wattage than your panels are rated for under good conditions and you will have days where you get essentially nothing. FLA batteries alone can reduce your effective efficiency lower than %50 under certain conditions and Iit looks like you may be setting yourself up for those conditions. I would not expect better than %80 efficiency under the best of conditions. What you need to calculate is how many watts of power you will consume on the heaviest draw day and how much energy you will be able to produce. If you get this wrong you will end up frequently replacing your batteries.
 
what is the air pump for? It uses 3 amps according to Amazon. That’s almost 75watts. If you are running it 24 hours a day your setup won’t even run that one device. If you really want to only have the pump work when you have sufficient solar the simplest and probably cheapest thing to do is to is to purchase the recommended spec 200w solar panel for the pump and run it separately from the rest of your system. You will produce noticeably less wattage than your panels are rated for under good conditions and you will have days where you get essentially nothing. FLA batteries alone can reduce your effective efficiency lower than %50 under certain conditions and Iit looks like you may be setting yourself up for those conditions. I would not expect better than %80 efficiency under the best of conditions. What you need to calculate is how many watts of power you will consume on the heaviest draw day and how much energy you will be able to produce. If you get this wrong you will end up frequently replacing your batteries.

The air pump is for ventilation, its a bit of an add on really. The well house is essentially built on a spring, there is water coming out of the ground everywhere . Therefore it’s really quite damp and humid in there. I’ve put normal vents in the building, one low to the ground and one in the apex of the roof. This should help airflow.

I thought that if I’ve got a surplus supply of power from the panels it would be a good idea to put it into the air pump. If it complicates the system though I’ll do without and keep an eye on the humidity and temp in the well house. I can always add it at a later date. The last thing I want is my lovely building turning into a mouldy sweat box.

How much the pump runs it dependent on our water consumption. At the moment we use 350 gallons per week. If the pump has a flow rate of 3GPM Then we only only need to run it for 2 hours per week. Even if we doubled our water consumption 700 gallons a week we’d only need to run the pump 4 hours a week.

I’m based in Oklahoma, it would be very rare to not get 4 decent hours of solar in a week. But if we didn’t we’ve got a 1500gallon storage tank to fall back on.

The 1500g tank is gravity fed by the 275g tank up in the well house. It’s controlled by a float valve so will always be full.

I was thinking about a programmable volt sensing relay. Setting it to the same voltage the Charge controller is when the battery is in float.

This would mean the relay would only be triggered when the batteries are fully charged. The problem with this is that if the load becomes more than the panels are producing the relay will switch back and forth as clouds pass over. Not the end of the world but could give the relay a shorter life span.

I also thought of putting the volt sensing relay in between the panels and the charge controller and setting it to just above the vmp of the array. This way the fan would only come on when the panels are producing substantial power.

Is there any weight to these ideas? Or are they flawed?

I don’t know, maybe I’m over complicating things. The only load that needs to be powered at night is the heat pad so I could have that wired directly to the batteries and have the charge controller programmed to only run during daylight hours and scrap the fan for now.
 
I’m not sure yet because I haven’t bought it yet. I think around the 30-40w range. It’s to go around the filter, the only part of the system I can’t insulate with pool noodles.

I was originally going to use a string of incandescent bulbs but a heat pad should work better.
 
I’m not sure yet because I haven’t bought it yet. I think around the 30-40w range. It’s to go around the filter, the only part of the system I can’t insulate with pool noodles.

I was originally going to use a string of incandescent bulbs but a heat pad should work better.
 
Because the well was drilled a couple of months ago, in the wet season. I don’t know how much the static water level will drop in the summer. At 70’ even if the water level drops by 20’ I’ve still got a buffer.

That and 70’ is how far #10 wire can provide 5a on a 24v system with a 3% voltage drop
 
The air pump is for ventilation, its a bit of an add on really. The well house is essentially built on a spring, there is water coming out of the ground everywhere . Therefore it’s really quite damp and humid in there. I’ve put normal vents in the building, one low to the ground and one in the apex of the roof. This should help airflow.

I thought that if I’ve got a surplus supply of power from the panels it would be a good idea to put it into the air pump. If it complicates the system though I’ll do without and keep an eye on the humidity and temp in the well house. I can always add it at a later date. The last thing I want is my lovely building turning into a mouldy sweat box.

How much the pump runs it dependent on our water consumption. At the moment we use 350 gallons per week. If the pump has a flow rate of 3GPM Then we only only need to run it for 2 hours per week. Even if we doubled our water consumption 700 gallons a week we’d only need to run the pump 4 hours a week.

I’m based in Oklahoma, it would be very rare to not get 4 decent hours of solar in a week. But if we didn’t we’ve got a 1500gallon storage tank to fall back on.

The 1500g tank is gravity fed by the 275g tank up in the well house. It’s controlled by a float valve so will always be full.

I was thinking about a programmable volt sensing relay. Setting it to the same voltage the Charge controller is when the battery is in float.

This would mean the relay would only be triggered when the batteries are fully charged. The problem with this is that if the load becomes more than the panels are producing the relay will switch back and forth as clouds pass over. Not the end of the world but could give the relay a shorter life span.

I also thought of putting the volt sensing relay in between the panels and the charge controller and setting it to just above the vmp of the array. This way the fan would only come on when the panels are producing substantial power.

Is there any weight to these ideas? Or are they flawed?

I don’t know, maybe I’m over complicating things. The only load that needs to be powered at night is the heat pad so I could have that wired directly to the batteries and have the charge controller programmed to only run during daylight hours and scrap the fan for now.
You have a lot of great ideas. If you are not adverse to spending a little more money if a few angles don’t quite work as you had hoped it will be worth the effort for education alone. I would suggest that you research fla batteries and their charging and discharging characteristics the voltage sensing relays might be quite an art to get working properly on fla. Make sure you have at least enough power on paper for all your loads to work if it falls short mathematicaly your project will be doomed from the start. With fla batteries I expect you will get no more than %50 of the rated energy of the solar actually usable without sun and %70 to 80 when running directly from the panels.
 
You have a lot of great ideas. If you are not adverse to spending a little more money if a few angles don’t quite work as you had hoped it will be worth the effort for education alone. I would suggest that you research fla batteries and their charging and discharging characteristics the voltage sensing relays might be quite an art to get working properly on fla. Make sure you have at least enough power on paper for all your loads to work if it falls short mathematicaly your project will be doomed from the start. With fla batteries I expect you will get no more than %50 of the rated energy of the solar actually usable without sun and %70 to 80 when running directly from the panels.
Thanks, FLA is definitely not my first choice but it’s what I’ve got at the moment. I’ll go with LiFe at some point in the future probably. I’ll do more research into the details of FLA in the meantime though.

I think I’m going with the KISS method to begin with, Keep It Simple Stupid.

I’ll program the charge controller to operate during daylight hours only and have the heat pad bypass the charge controller so that can come on at any time. I’ll monitor the system for a while to see it’s capabilities before I add the extractor fan.

I got the last of the components in the mail today so I can finish installing the system over the next few days. I’ll post a full write up on here once it’s done.

I attached a photo of the well house in the snow last week
 
Thanks, FLA is definitely not my first choice but it’s what I’ve got at the moment. I’ll go with LiFe at some point in the future probably. I’ll do more research into the details of FLA in the meantime though.

I think I’m going with the KISS method to begin with, Keep It Simple Stupid.

I’ll program the charge controller to operate during daylight hours only and have the heat pad bypass the charge controller so that can come on at any time. I’ll monitor the system for a while to see it’s capabilities before I add the extractor fan.

I got the last of the components in the mail today so I can finish installing the system over the next few days. I’ll post a full write up on here once it’s done.

I attached a photo of the well house in the snow last week
Great I will be looking forward to your report.
 
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