12 Volt Solar Setup for Garage Only

[john95]

Hello guys! I'd like to build a very small 12 Volt Solar Setup for my garage.
My consumption will be limited to:

5x 12 volt 7 watts x 4 hrs. = 140 watts, LED lights and a 65" LED TV 213 watts x 2 hrs. daily = 426. My total power consumption will be about 566 Watts. I love to make it a least to 1.5 kWh of daily consumption.

For this setup I was thinking to get the following components:

2x Tojan T105 6 volt 225 AH 2.7 kWh of storage
1x Renogy 100 Watt 12 Volt Polycrystalline Solar Panel (Perhaps I need 3 of these to fill up the batteries or to return my 1.5 kWh consumption)
1x MPPT L60 Charger Controller
and 1x MicroSolar 12 Volt 2000 Watts Pure Sine Wave Inverter

Can you guys recommend me a better way to achieve this? Thanks for reading.

[Sunking]

1.5 Kwh per day is doable, but no way with what you have listed. First you gotta up the panel wattage to 500 watts minimum to 750 watts depending on your location and time of year use, battery size up to 600 AH, a good true MPPT 40 amp controller, and downgrade the Inverter to a 500 watt TSW. It wil cost you a lot more than you thought.

[john95]

Thanks for your info Sunking! Yes, you are right! It'd cost me more than what I thought. In that case, I'll have to keep my usage under 500 Watts.
I get about 6 hrs of sun light here in California. This will be about 600 watts of my 100 watt solar panel.

All I need is one 7 watt LED light bulb x 6 hrs. = 42 Watts and the 65" LED TV 213 x 2 hrs. = 426 Watts. Total use will be: 468 Watts under the 500 Watts mark. Less than $600 budget.
I was thinking on using only 12 Volt DC appliances so I don't even have to use an inverter. 120 Volt AC appliances are the power hungry ones any ways. I may get a 12 Volt DC TV, car radio, Fan, Fridge, etc.

[Logan5]

Now you got it. If your runs are short DC is the way to go.

[SunEagle]

Thanks for your info Sunking! Yes, you are right! It'd cost me more than what I thought. In that case, I'll have to keep my usage under 500 Watts.
I get about 6 hrs of sun light here in California. This will be about 600 watts of my 100 watt solar panel.

All I need is one 7 watt LED light bulb x 6 hrs. = 42 Watts and the 65" LED TV 213 x 2 hrs. = 426 Watts. Total use will be: 468 Watts under the 500 Watts mark. Less than $600 budget.
I was thinking on using only 12 Volt DC appliances so I don't even have to use an inverter. 120 Volt AC appliances are the power hungry ones any ways. I may get a 12 Volt DC TV, car radio, Fan, Fridge, etc.

Even with DC appliance you still get losses as well as possible higher wattage usage.

Do not under estimate your daily watt hour usage because you can deplete your battery and may not be able to recharge it back because of poor sunlight the next day. Saving a few bucks up front on your system may cause you to spend a lot more latter on.

IMO you can get a system that will safely generate 700 watt hours daily for about $1500. That would include about 400 watts of pv, 2 x 6v 225Ah batteries, 30amp MPPT CC and a 600watt pure sine wave inverter if needed. That gives you a lot of options to run different types of loads.

[john95]

@Logan5:
Thanks for your comment! How long is too long in feet to loose DC considerably? The TV will be located under 12 feet away from where the batteries will be installed.

[Logan5]

it depends on the watts and the native voltage of the TV, if the TV is 19 volts. I would run 24 volts to behind the TV and then step down to 19 volts. If you run 12 volts and step up to 19 your TV will use much more watts even over a short run. I run 48 volts over awg 10 wire and step down to 19 volts with almost no loss. the higher the voltage the longer run is possible. 12 feet is not a very long run @ 12 volts, much better at 24 or 48

[john95]

Even with DC appliance you still get losses as well as possible higher wattage usage.

Do not under estimate your daily watt hour usage because you can deplete your battery and may not be able to recharge it back because of poor sunlight the next day. Saving a few bucks up front on your system may cause you to spend a lot more latter on.

IMO you can get a system that will safely generate 700 watt hours daily for about $1500. That would include about 400 watts of pv, 2 x 6v 225Ah batteries, 30amp MPPT CC and a 600watt pure sine wave inverter if needed. That gives you a lot of options to run different types of loads.

Thanks for your info. At the beginning I was thinking on a "portable" 12 volt solar setup. A very simple and cheap setup but that will be enough electricity to run lights and very small 12 Volt DC devices. I thought about a $400 ~ $500 budget but you are giving me better ideas to jump into a $1,500 ~ $2,000 12 Volt solar setup.

There is a gazillion components to choose from in the market. What specific brand of components do I need to get 1.5 kWh? Thanks.

[SunEagle]

Thanks for your info. At the beginning I was thinking on a "portable" 12 volt solar setup. A very simple and cheap setup but that will be enough electricity to run lights and very small 12 Volt DC devices. I thought about a $400 ~ $500 budget but you are giving me better ideas to jump into a $1,500 ~ $2,000 12 Volt solar setup.

There is a gazillion components to choose from in the market. What specific brand of components do I need to get 1.5 kWh? Thanks.

For $400 to $500 you can get something that will generate about 200 watt hours and is very portable. Like the one in the following pictures.

The panel is only 80 watts (it should be 100 watt) the battery is an Optima 65Ah, and the inverter is a cheap 250 watt modified sine wave.

Oh. I did build a bigger system that gets me about 600 watt hours a day but I spent close to $2500 because I got 80 an 90 watt panels instead of 200 watt ones and 4 x 12v 50Ah batteries instead of 2 x 6v 225Ah ones. Wasted $1000 but I learned what not to do.

[john95]

Wow SunEagle! This is very cute! I like it. Thanks for sharing.

4x Tojan T105 6 volt 225 AH 5.4 kWh of storage $480
3x Renogy 100 Watt 12 Volt Polycrystalline Solar Panel $369
1x MPPT L60 Charger Controller $59.00
1x Reliable RBP-500S-LED 500 watt 12 Volt Pure Sine Solar Power Inverter $109

About 1.4 kWh usage per day.

Total: $1,017.00

[SunEagle]

Wow SunEagle! This is very cute! I like it. Thanks for sharing.

4x Tojan T105 6 volt 225 AH 5.4 kWh of storage $480
3x Renogy 100 Watt 12 Volt Polycrystalline Solar Panel $369
1x MPPT L60 Charger Controller $59.00
1x Reliable RBP-500S-LED 500 watt 12 Volt Pure Sine Solar Power Inverter $109

About 1.4 kWh usage per day.

Total: $1,017.00

Those batteries are a good price but the problem is that with only 300 watts of solar panels you will only get 25 charging amps with that MPPT CC. That gets you about a C/18 for the 450Ah battery system which is too slow.

You need about 45 amps (C/10) which at 12volt is over 500 watts of panels. So either use half of those Trojan for a 12v 225Ah system or get more solar wattage.

[john95]

For the moment what I really need is electricity for my garage 7 watt bulb lights, a car radio and a 12 volt 22" LED TV. I don't even need an inverter for this. I guess that's less tnan 300 watts a day of usage.

[SunEagle]

For the moment what I really need is electricity for my garage 7 watt bulb lights, a car radio and a 12 volt 22" LED TV. I don't even need an inverter for this. I guess that's less tnan 300 watts a day of usage.

Whatever system you build remember that if you use FLA batteries they need to be charged at a rate between C/8 and C/12 where C = the AH rating of the system. Quick rule of thumb is C/10 or just divide the Ah by 10 and then you can calculate the amount of solar pv wattage to get the charging amps.

If you get too many amps you can fry the batteries. Too little and their plates can sulfate and reduce the amount that can charge.

[john95]

Whatever system you build remember that if you use FLA batteries they need to be charged at a rate between C/8 and C/12 where C = the AH rating of the system. Quick rule of thumb is C/10 or just divide the Ah by 10 and then you can calculate the amount of solar pv wattage to get the charging amps.

If you get too many amps you can fry the batteries. Too little and their plates can sulfate and reduce the amount that can charge.

It is very simple then. I thought you were telling me that I needed 27x 100 watts solar panels to achieve the charging per hour requirement of full 225 AH of my batteries. Now I know is only a portion of the whole 225 AH rated battery. Putting in more simple terms, one needs 10% per hour of charging power of the total rated battery AH. To get to exact figures is darn hard!

In my situation according to you:
To get the C/10 charge requirement all I have to do is divide 225/10=22.5 which is the charging requirement.
22.5 AH is 270 watts. Where am I going to get 1x 270 watt 12 volts solar panel? If I get 3x 100 it goes over the 270 watts. Sure I can always get 1x 100 watt panel and 1x 160 watt panel for a total of 260 watts, but it will not get the exact charging requirement. I see that some are monocrystalline and others are polycristalline. Can they even be mixed? or I have to use the same kind?

How do they come to this requirement of C/8 and C/12?

[SunEagle]

It is very simple then. I thought you were telling me that I needed 27x 100 watts solar panels to achieve the charging per hour requirement of full 225 AH of my batteries. Now I know is only a portion of the whole 225 AH rated battery. Putting in more simple terms, one needs 10% per hour of charging power of the total rated battery AH. To get to exact figures is darn hard!

In my situation according to you:
To get the C/10 charge requirement all I have to do is divide 225/10=22.5 which is the charging requirement.
22.5 AH is 270 watts. Where am I going to get 1x 270 watt 12 volts solar panel? If I get 3x 100 it goes over the 270 watts. Sure I can always get 1x 100 watt panel and 1x 160 watt panel for a total of 260 watts, but it will not get the exact charging requirement. I see that some are monocrystalline and others are polycristalline. Can they even be mixed? or I have to use the same kind?

How do they come to this requirement of C/8 and C/12?

Just remember a PWM CC works as Amps in = Amps out. While a MPPT CC works as Watts in = Watts out which is more efficient.

You would usually wire panels to a PWM CC in parallel so the Imp of each panels is added up but the wire size has to be larger due to the higher amps.

A MPPT CC allows you to wire the panels in series which keeps the wire size down yet you get the full wattage used converted to charging amps.

As for the type of solar panel. You can mix a mono cell with a poly type. Just make sure the Vmp is within 5% of each other or they might fight.

[john95]

Updated Components for my garage Small Solar 12 volt Project 1.3 kWh Max usage:

1x Renogy 100 Watt 12 Volt Polycrystalline Solar Panel 122.99
1x Hightech Solar 160 watt 12 volt Monocrystalline Solar panel $165.00
2x TROJAN T105 6 VOLT 225 AH $240.00 (2.7 kWh Storage)
1x HQST 40A MPPT Solar Charge Controller $153.00
1x AIMS 600 Watts Pure Sine Inverter $129.00

Total of $809.00

If I go with the 3x 100 watts panels is more money and I get out of the charging requirement of 22.5 A
260 watts = 21.66 A and 300 watts = 25 A.
So, I'm closer to the 22.5 requirement with 260 Watts than with 300 watts. But I may get only 270 watts with the 300 watts panels due to other factors.

Should I get the 3x 300 watts panels better?

[john95]

Let's do some simple calculations assuming that all these components last 36 months working fine, $809/36=22.47 per month:

1.3 kWh x 30 days=39
22.47/39= 0.57 per kWh
Still way more expensive than my POCO.

These components must have last 10 years to come down to $0.17 per kWh, just 0.03 under my POCO price per kWh
And of course just the solar panels may last more that 10 years; the other stuff will have to be replaced many times to go more than 10 years.