Need Help with DIY Solar Panel Setup for Current Prep Situation

jerryv · 03-16-20, 11:02 PM

TLDR: With current resources available, how can I setup these panels (parallel, series/string, and how many, etc)? And are my components ok for now (or should I add/exchange)?

I'm working on a solar panel setup for my families house that wont be grid tied in right now. Maybe later once situation with Covid19 clears up and it would be easier to get right supplies and permitting setup with city. I purchase the solar panels new locally (which I rather not return) and ordered other components from Amazon and Home Depot (which can be returned/exchanged). Let me list out what I have:

2 @ BestEquip 60A MPPT Solar Charge Controller Auto Battery Regulator PV 150V MAX Input MPPT Charge Controller Finger Touch Interface for Solar Panel and Lithium Battery

1 @ AIMS Power PWRINV500048W Power Inverter, 5000 Watt Max Continuous Power, 48V, 10000 Watts Peak Surge Power, Modified Sine Wave, Cooling Fan Thermally Controlled, AC Direct Connect Terminal

4 @ EverStart Maxx Lead Acid Marine & RV Battery, Group Size 29DC

I was planning to have a 48v system with 5kw and 120/110v AC (ideally would like 240/220 but might be out current budget)

Here are my questions. I've been researching these like crazy and sites either point to spam, solar company sales sites, or pinterest for some reason.

- What configuration should I do my panels in, parallel, series/stringed, and how many?
- What sort of combiner box should I get for above setup?
- Would I need another charge controller for the setup (I know the ones I do have are not as robust but with logistics/resources slowing down trying to make something work)?
- Can I ground each panel to the rails (unistruts) and then ground the unistruts to system (combiner box, down other components then to ground) or do/should I run a continuous wire that connects to all panels, rails and then down?

Once I know this, I can research what gauge of wire I should need as it would give me an idea of W, V, A are going through, was thinking of 10AWG for the DC wires from panels to combiner box and then maybe something thicker from there to inverter. And of course even thicker for battery terminals.

Thanks in advance.

MN Renovator · 03-17-20, 12:22 AM

What sort of solar modules were you considering? 60 cell modules? 72 cell modules? 36 cell modules?
What total solar module nameplate wattage are you aiming for?

If you've already decided or have some modules you are looking at:
What is their nameplate voltage and total wattage of each module?
How many modules were you looking to get?

As a sanity check:
What are you looking to do with this system? (aka what are you looking to power with it)

This information along with the information from the solar charge controller you bought should help you figure out how to wire them in a way that won't blow up your solar charge controller or substantially limit output.

Don't expect the Walmart "deep cycle" batteries to last too long. Lead-acid batteries don't last long to begin with but taking small batteries(relative to typical solar applications) that are not designed for solar might not last as long as you expect, but it all depends on usage. Lead-acid batteries of any type don't like to be cycled down more than 50% from full, lesser quality batteries you would want to baby more.

jerryv · 03-17-20, 08:40 PM

Quote:

Originally Posted by MN Renovator

What sort of solar modules were you considering? 60 cell modules? 72 cell modules? 36 cell modules?
What total solar module nameplate wattage are you aiming for?

If you've already decided or have some modules you are looking at:
What is their nameplate voltage and total wattage of each module?
How many modules were you looking to get?

As a sanity check:
What are you looking to do with this system? (aka what are you looking to power with it)

This information along with the information from the solar charge controller you bought should help you figure out how to wire them in a way that won't blow up your solar charge controller or substantially limit output.

Don't expect the Walmart "deep cycle" batteries to last too long. Lead-acid batteries don't last long to begin with but taking small batteries(relative to typical solar applications) that are not designed for solar might not last as long as you expect, but it all depends on usage. Lead-acid batteries of any type don't like to be cycled down more than 50% from full, lesser quality batteries you would want to baby more.

Thanks for replying. So I have the panels now, 15 @ LG 335W. I've attached images of the back of the panels, the charge controllers I currently have and the inverter.
I'm not having it grid tied as the city(permitting) is going to be on hold for a while so just going to move some key items to this setup, so sort of like off the grid for these items. Later when things clear up with COVID19, would like to work on the grid tie solution which I know would require some components changed but right now do not have the resources (logistics and funds) so want to get this setup going with what I have. Just not sure how to connect everything and have been researching a lot on Google. Appreciate your help.

jjackstone · 03-18-20, 01:14 PM

First thing I notice is that your inverter has a modified sine wave rather than a pure sine wave output. In general, things with motors don't like modified sine waves. Refrigerators, air conditioners, blower fans. It tends to make them work too hard and can actually harm them. I would do a little research on the inverter and see if others have successfully used it in a home situation.

Your MPPT controllers have a maximum input voltage of 150 volts and your panels are rated at 41 volts open circuit. To see how many panels you can use in series with the controller you add up the OC voltage and then you have to give the system a derating factor for cold temperatures. Normally for every degree C less than 25 there is about a .003 rise in voltage output. So at 0 degees C (32F), your output voltage can increase to 44 volts. If you get to negative 10C then your voltage can be as high as 45.3 volts per panel. So if you have three panels in series, then your max output voltage would be 136 volts. I don't know if you can gang your controllers together or not, but if not I wouldn't put more than three panels in series. And if you get colder in your area than my example, I would recalculate the numbers first.

All that said, I would go to Youtube and look up the AltE store and go through as many videos as you can. All this information is available for free through the videos.

JJ

MN Renovator · 03-23-20, 08:30 PM

I agree that 3 solar panels in series would get you to the terminal voltage you are looking to supply to the charge controllers. 5kw system is a bigger system than what I have on my house which will be excellent to have grid-tied once you are able to.

I couldn't find the latest Ah spec on the batteries you bought, but it seems that they used to advertised with a 105Ah spec. You wouldn't want to pull more than half of that from them if you want them to have a reasonable lifetime(relative to any other lead acid battery). ..so your 48v system will have about 2.5kwh usable capacity, which would be replenished very quickly with reasonable sunlight if the power usage isn't high at the same time but if it's not sunny they will drain down very quickly depending on your power usage. If you don't have much power usage when the sun isn't out you might make it to the next day if you keep the power usage minimal such as a refrigerator, meager use of LED/CFL lighting, a furnace blower running only when it's heating, not leaving computers/appliances on overnight. These batteries wouldn't run electric strip heat, a heat pump, or an air conditioner. ..although depending on the power usage of an air conditioner, your system might be able to run a small 120 volt window air conditioner if the batteries are full when it tries to start and the inverter can handle the motor starting load. I disagree with jjackstone and I run inverters with motor loads as long as the inverter is able to start the motor, some don't handle inductive loads well and they shut down or the motor doesn't run properly unless there is enough of a resistive load to balance out the negative properties of the inductive load. Since you have a 5000 watt continuous inverter, it would likely have no issues starting up most appliance loads.

Your inverter choice is a 120 volt unit which means you won't be able to run any 240v appliances or connect it to your house service panel unless you use a transfer switch designed for 120 volt generators and have it switch power to one or a few circuits in the panel. ..again not sure on what you are planning to power with this system in the off-grid configuration

You said this was for a prep situation, I personally plan for not having available electricity and have a gas generator to run my furnace to keep my pipes from freezing in the winter which means with moderately cold weather like we have now. I wouldn't bother, I'd just put on a sweater, coat, jeans, and thermals. I might run the fridge until I can get eat enough food until I can get a cooler filled with ice and then I'd eat the food ASAP. In the winter, the cooler goes outside or in the garage to preserve the ice, in the summer the cooler stays in the basement where it's coolest.

gadget · 03-25-20, 10:43 AM

I was looking to go grid tie till I read the contract. I'm not giving my local government the right to enter my house when ever they want.

You will also want to buy panels that are UL listed/certified(?) for grid tie if you plan on going that route later on. There is also some issue with static electricity build up on panels when grid tied requiring positive ground panels and components. You need to check each piece for how it is grounded when you buy them. Going grid tie after the fact may have issues if your not a licensed contractor depending on your local gov. Contractors may not want to use your parts since they want to sell you a whole system.

You may still have issues with your city about mounting panels on your roof even if its not grid tie. Also with all the wiring requiring permitting. Sometimes there are loop holes for low voltage DC. On way around this is putting panels out on your back yard lawn but this has issues with theft.

I'm going the non grid tie route and using my panels for specific loads only, with the option to power other items in a power outage.

My main loads are growing lights for indoor veggies, heat pumps for the house in winter and greenhouse, summer time swamp coolers, etc..

I would return the modified sine wave inverter. They should stop selling them.

03-16-20, 11:02 PM	#1
jerryv Lurking Renovator Join Date: Mar 2020 Location: Texas Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts	Need Help with DIY Solar Panel Setup for Current Prep Situation TLDR: With current resources available, how can I setup these panels (parallel, series/string, and how many, etc)? And are my components ok for now (or should I add/exchange)? I'm working on a solar panel setup for my families house that wont be grid tied in right now. Maybe later once situation with Covid19 clears up and it would be easier to get right supplies and permitting setup with city. I purchase the solar panels new locally (which I rather not return) and ordered other components from Amazon and Home Depot (which can be returned/exchanged). Let me list out what I have: 2 @ BestEquip 60A MPPT Solar Charge Controller Auto Battery Regulator PV 150V MAX Input MPPT Charge Controller Finger Touch Interface for Solar Panel and Lithium Battery 1 @ AIMS Power PWRINV500048W Power Inverter, 5000 Watt Max Continuous Power, 48V, 10000 Watts Peak Surge Power, Modified Sine Wave, Cooling Fan Thermally Controlled, AC Direct Connect Terminal 4 @ EverStart Maxx Lead Acid Marine & RV Battery, Group Size 29DC I was planning to have a 48v system with 5kw and 120/110v AC (ideally would like 240/220 but might be out current budget) Here are my questions. I've been researching these like crazy and sites either point to spam, solar company sales sites, or pinterest for some reason. - What configuration should I do my panels in, parallel, series/stringed, and how many? - What sort of combiner box should I get for above setup? - Would I need another charge controller for the setup (I know the ones I do have are not as robust but with logistics/resources slowing down trying to make something work)? - Can I ground each panel to the rails (unistruts) and then ground the unistruts to system (combiner box, down other components then to ground) or do/should I run a continuous wire that connects to all panels, rails and then down? Once I know this, I can research what gauge of wire I should need as it would give me an idea of W, V, A are going through, was thinking of 10AWG for the DC wires from panels to combiner box and then maybe something thicker from there to inverter. And of course even thicker for battery terminals. Thanks in advance.

03-17-20, 12:22 AM	#2
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 940 Thanks: 41 Thanked 117 Times in 91 Posts	What sort of solar modules were you considering? 60 cell modules? 72 cell modules? 36 cell modules? What total solar module nameplate wattage are you aiming for? If you've already decided or have some modules you are looking at: What is their nameplate voltage and total wattage of each module? How many modules were you looking to get? As a sanity check: What are you looking to do with this system? (aka what are you looking to power with it) This information along with the information from the solar charge controller you bought should help you figure out how to wire them in a way that won't blow up your solar charge controller or substantially limit output. Don't expect the Walmart "deep cycle" batteries to last too long. Lead-acid batteries don't last long to begin with but taking small batteries(relative to typical solar applications) that are not designed for solar might not last as long as you expect, but it all depends on usage. Lead-acid batteries of any type don't like to be cycled down more than 50% from full, lesser quality batteries you would want to baby more.

03-18-20, 01:14 PM	#4
jjackstone Helper EcoRenovator Join Date: Mar 2009 Location: Sacramento,Ca Posts: 88 Thanks: 5 Thanked 32 Times in 23 Posts	First thing I notice is that your inverter has a modified sine wave rather than a pure sine wave output. In general, things with motors don't like modified sine waves. Refrigerators, air conditioners, blower fans. It tends to make them work too hard and can actually harm them. I would do a little research on the inverter and see if others have successfully used it in a home situation. Your MPPT controllers have a maximum input voltage of 150 volts and your panels are rated at 41 volts open circuit. To see how many panels you can use in series with the controller you add up the OC voltage and then you have to give the system a derating factor for cold temperatures. Normally for every degree C less than 25 there is about a .003 rise in voltage output. So at 0 degees C (32F), your output voltage can increase to 44 volts. If you get to negative 10C then your voltage can be as high as 45.3 volts per panel. So if you have three panels in series, then your max output voltage would be 136 volts. I don't know if you can gang your controllers together or not, but if not I wouldn't put more than three panels in series. And if you get colder in your area than my example, I would recalculate the numbers first. All that said, I would go to Youtube and look up the AltE store and go through as many videos as you can. All this information is available for free through the videos. JJ

03-23-20, 08:30 PM	#5
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 940 Thanks: 41 Thanked 117 Times in 91 Posts	I agree that 3 solar panels in series would get you to the terminal voltage you are looking to supply to the charge controllers. 5kw system is a bigger system than what I have on my house which will be excellent to have grid-tied once you are able to. I couldn't find the latest Ah spec on the batteries you bought, but it seems that they used to advertised with a 105Ah spec. You wouldn't want to pull more than half of that from them if you want them to have a reasonable lifetime(relative to any other lead acid battery). ..so your 48v system will have about 2.5kwh usable capacity, which would be replenished very quickly with reasonable sunlight if the power usage isn't high at the same time but if it's not sunny they will drain down very quickly depending on your power usage. If you don't have much power usage when the sun isn't out you might make it to the next day if you keep the power usage minimal such as a refrigerator, meager use of LED/CFL lighting, a furnace blower running only when it's heating, not leaving computers/appliances on overnight. These batteries wouldn't run electric strip heat, a heat pump, or an air conditioner. ..although depending on the power usage of an air conditioner, your system might be able to run a small 120 volt window air conditioner if the batteries are full when it tries to start and the inverter can handle the motor starting load. I disagree with jjackstone and I run inverters with motor loads as long as the inverter is able to start the motor, some don't handle inductive loads well and they shut down or the motor doesn't run properly unless there is enough of a resistive load to balance out the negative properties of the inductive load. Since you have a 5000 watt continuous inverter, it would likely have no issues starting up most appliance loads. Your inverter choice is a 120 volt unit which means you won't be able to run any 240v appliances or connect it to your house service panel unless you use a transfer switch designed for 120 volt generators and have it switch power to one or a few circuits in the panel. ..again not sure on what you are planning to power with this system in the off-grid configuration You said this was for a prep situation, I personally plan for not having available electricity and have a gas generator to run my furnace to keep my pipes from freezing in the winter which means with moderately cold weather like we have now. I wouldn't bother, I'd just put on a sweater, coat, jeans, and thermals. I might run the fridge until I can get eat enough food until I can get a cooler filled with ice and then I'd eat the food ASAP. In the winter, the cooler goes outside or in the garage to preserve the ice, in the summer the cooler stays in the basement where it's coolest.

03-25-20, 10:43 AM	#6
gadget Helper EcoRenovator Join Date: Dec 2019 Location: Northern Utah Posts: 49 Thanks: 1 Thanked 2 Times in 2 Posts	I was looking to go grid tie till I read the contract. I'm not giving my local government the right to enter my house when ever they want. You will also want to buy panels that are UL listed/certified(?) for grid tie if you plan on going that route later on. There is also some issue with static electricity build up on panels when grid tied requiring positive ground panels and components. You need to check each piece for how it is grounded when you buy them. Going grid tie after the fact may have issues if your not a licensed contractor depending on your local gov. Contractors may not want to use your parts since they want to sell you a whole system. You may still have issues with your city about mounting panels on your roof even if its not grid tie. Also with all the wiring requiring permitting. Sometimes there are loop holes for low voltage DC. On way around this is putting panels out on your back yard lawn but this has issues with theft. I'm going the non grid tie route and using my panels for specific loads only, with the option to power other items in a power outage. My main loads are growing lights for indoor veggies, heat pumps for the house in winter and greenhouse, summer time swamp coolers, etc.. I would return the modified sine wave inverter. They should stop selling them.