DIY Solar Panels

[Pedernal]

I had not read through this hole thread until now. Lots of of cool projects going on.

I have some experience working on off grid communication sites. We ran both solar and wind to most sights. Most of the stuff we used was Morningstar brand. I have no affiliation to them it’s just what we were using.

One thing I can suggest to keep cost lower is controllers that can handle higher input voltage. Higher voltage to current ratio will allow for lower gauge wire which is crazy high right now. One of there 600 V controllers can handle up to 3200 watts worth of panels.

[texan4ut]

Do you have the lights and other items connected through the load output on the charge controller? This could be the problem. They aren’t designed to handle much of a load and are primarily designed to only run one or two lights when the panels stop putting out power.


Are the lights you are running 12v, 24v, or 120v lights? This also matters and can drastically change things. What size batteries are you running?

I have it hooked up per their instructions. On the bottom there is AC out, DC out, AC in as if it was hooked up to a generator or other AC source and Solar Panel in. Light are 120 Volts. Batteries are 12 Volt Battle Tanks from Amazon. I will look again to make sure it is connected correctly. Thing is the power LED shows power from solar to battery and to AC inverter. As soon as I turn on AC anything I hear a click in the unit and then it quits sending solar power to Batteries and AC Thanks

[91cavgt]

I looked for those batteries online and can’t find them. Do you have a link for them or any info on them like a model number? When searching on Amazon all I see is toys.

[texan4ut]

I looked for those batteries online and can’t find them. Do you have a link for them or any info on them like a model number? When searching on Amazon all I see is toys.

Had the name wrong VMax Charge Tank https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1 I still think the controller is bad. I was up there last Thursday to Monday. Didn't work right until Sunday then for some reason started working as should. Next trip up Christmas so I will see what it is doing. In the meantime I have bought another charge controller and a pure sine inverter. Going to hook that up to the same batteries.

[91cavgt]

Had the name wrong VMax Charge Tank https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1 I still think the controller is bad. I was up there last Thursday to Monday. Didn't work right until Sunday then for some reason started working as should. Next trip up Christmas so I will see what it is doing. In the meantime I have bought another charge controller and a pure sine inverter. Going to hook that up to the same batteries.

1. Those batteries are VERY small!!! They are only 35 amp/hr. If you have 2 of them wired in parallel then you effectively have a 70 amp/hr battery. This means that you can use a maximum of 70 amps over a 20 hour period. So, you can only pull about 3.5 amps of current over a 20 hour period! Only need to run the batteries for 10 hours at a time? Well, at a 10 hour rate you are still only looking at 5-6 amps of current. Most power inverters will pull 1-2 amps of current at idle with no load connected!! So right off the bat I see that you need more battery capacity.


2. Are all of your electrical items connected to the load connection on the charge controller or directly to the batteries?

[texan4ut]

1. Those batteries are VERY small!!! They are only 35 amp/hr. If you have 2 of them wired in parallel then you effectively have a 70 amp/hr battery. This means that you can use a maximum of 70 amps over a 20 hour period. So, you can only pull about 3.5 amps of current over a 20 hour period! Only need to run the batteries for 10 hours at a time? Well, at a 10 hour rate you are still only looking at 5-6 amps of current. Most power inverters will pull 1-2 amps of current at idle with no load connected!! So right off the bat I see that you need more battery capacity.


2. Are all of your electrical items connected to the load connection on the charge controller or directly to the batteries?

With that charge controller the inverter is built in so you have Solar in, battery in, ac out. Not sure how it is wired on the interior. I agree the batteries are too small. I installed a new controller and inverter and works as should however the batteries drain pretty quickly with just a 80w led bulb. Looking at LiPo type battery. How many amp hours should I be looking at. TIA

[Pedernal]

With that charge controller the inverter is built in so you have Solar in, battery in, ac out. Not sure how it is wired on the interior. I agree the batteries are too small. I installed a new controller and inverter and works as should however the batteries drain pretty quickly with just a 80w led bulb. Looking at LiPo type battery. How many amp hours should I be looking at. TIA

So an 80 watt lamp or load running on a 12 volt system will run at approximately 6.6 amps… multiply that by the hours you need/want to run it will give you the total amp hours you want… obviously, you would never run a battery down to Zero charge and you must consider where the battery manufacturer considers a safe cut off point… there are controllers that have a programmable low voltage disconnect (LVD) which you could then set to the manufacturer’s recommendation

[91cavgt]

With that charge controller the inverter is built in so you have Solar in, battery in, ac out. Not sure how it is wired on the interior. I agree the batteries are too small. I installed a new controller and inverter and works as should however the batteries drain pretty quickly with just a 80w led bulb. Looking at LiPo type battery. How many amp hours should I be looking at. TIA

It all depends on what you want to run off of the system, how long you plan on running it, and what kind of batteries you plan on using.


For example, with AGM and flooded batteries, you need to cut their amp/hr rating in half. This is because the only way to use all of the capacity on one of these batteries is to completely drain them which is VERY bad.

With lithium batteries, you will pay a lot more for them but they last longer and you can get the full rated capacity out of them. So 100 amp/hr capacity of lithium will basically be the equivalent of 200 amp/hr of AGM or wet cell batteries.


Just for running for an occasional weekend and only running a light or two, a small fan, and for recharging small electronics I’d say 100 amp/hr of lithium or 200 amp/hr of AGM or wet cell batteries.


If you are looking for batteries on a budget, search around for used telecom AGM batteries. These are typically 2-5 years old and will typically cost about $100 per 100 amp/hr of capacity. The downside of these batteries is they typically weigh 70-100 pounds each. Hope this helps.

[texan4ut]

It all depends on what you want to run off of the system, how long you plan on running it, and what kind of batteries you plan on using.


For example, with AGM and flooded batteries, you need to cut their amp/hr rating in half. This is because the only way to use all of the capacity on one of these batteries is to completely drain them which is VERY bad.

With lithium batteries, you will pay a lot more for them but they last longer and you can get the full rated capacity out of them. So 100 amp/hr capacity of lithium will basically be the equivalent of 200 amp/hr of AGM or wet cell batteries.


Just for running for an occasional weekend and only running a light or two, a small fan, and for recharging small electronics I’d say 100 amp/hr of lithium or 200 amp/hr of AGM or wet cell batteries.


If you are looking for batteries on a budget, search around for used telecom AGM batteries. These are typically 2-5 years old and will typically cost about $100 per 100 amp/hr of capacity. The downside of these batteries is they typically weigh 70-100 pounds each. Hope this helps.

Thanks I will look into various batteries. This solar thing is new to me.

[texan4ut]

I ended up buying an Enjoybot 100ah Lipo4 battery. After I got it installed let it charge for a day. I turned on the 3 shop light I currently have installed and had no issues all day. Battery stayed at 13.1 volts. When the sun went down they battery stayed at 13.1 volts for a couple of hours then began to slowly drop 12.9 volts when I left the building. I did wake up around 2:30 am for a bathroom trip and looked out at the building and lights were still on. I got up at 6:30 am and the lights were off. So voltage dropped to minimum. Sun up didn't take long and battery was up and lights working. Next two nights I tried leaving one on and it never ran the battery to minimum and same with two on all night. I have now bought a second battery like the 1sy so I should double my usage time. Thanks for the suggestion on lithium batteries 91cavgt. They are more expensive although these were $368.00 and free shipping per each.

[91cavgt]

I ended up buying an Enjoybot 100ah Lipo4 battery. After I got it installed let it charge for a day. I turned on the 3 shop light I currently have installed and had no issues all day. Battery stayed at 13.1 volts. When the sun went down they battery stayed at 13.1 volts for a couple of hours then began to slowly drop 12.9 volts when I left the building. I did wake up around 2:30 am for a bathroom trip and looked out at the building and lights were still on. I got up at 6:30 am and the lights were off. So voltage dropped to minimum. Sun up didn't take long and battery was up and lights working. Next two nights I tried leaving one on and it never ran the battery to minimum and same with two on all night. I have now bought a second battery like the 1sy so I should double my usage time. Thanks for the suggestion on lithium batteries 91cavgt. They are more expensive although these were $368.00 and free shipping per each.

That’s good to hear! Lithium definitely hurts the wallet when you buy them, but with how long they last, they pay off in the long run. $368 for a prebuilt 100 amp/hr battery really is not that bad.