Small PV system for college

[ZzZr]

Hello everyone, This is my first post here, I love PV .

I have to put together a small solar system for a college project. The thing is that I have solar cells with 3.65A and 0.6V. Now if I paralel two groups of two cells connected in series I will double the amps and volts. And the output power will be like 8W. The question is, do a 1.2V panel really work? Can I charge a 12V battery? I mean the panel will be 8W and high amperage low voltage. Do I need to have a minimum 12V panel to charge battery? This means I will have to put in series 20 cells to obtain 12V. Are there high voltage low amperage solar cells so I don't need to put together so many cells. I will greatly appreciate your answer.

[lkruper]

Hello everyone, This is my first post here, I love PV .

I have to put together a small solar system for a college project. The thing is that I have solar cells with 3.65A and 0.6V. Now if I paralel two groups of two cells connected in series I will double the amps and volts. And the output power will be like 8W. The question is, do a 1.2V panel really work? Can I charge a 12V battery? I mean the panel will be 8W and high amperage low voltage. Do I need to have a minimum 12V panel to charge battery? This means I will have to put in series 20 cells to obtain 12V. Are there high voltage low amperage solar cells so I don't need to put together so many cells. I will greatly appreciate your answer.

You could make 12 of the 1.2 v panels and wire them together to get 14.4 v BTW You will need more than 12 volts to charge a 12v battery.

What is the goal of the project?

[ZzZr]

You could make 12 of the 1.2 v panels and wire them together to get 14.4 v BTW You will need more than 12 volts to charge a 12v battery.

What is the goal of the project?

The goal is to show a small PV system built by me from sun to a lighting bulb, or even some 220V devices and explain how it works. Probably dumb, but I missed something and I didn't know that there's a minimum voltage to charge battery I was just considering the overall Watts power.

Here, the cells I found are like mentioned previously 0.6V 6.3A. The battery is 12V 7AH. I have to build the system to output a minimum voltage of 12V, right? does amperage matters?

I think I will have to buy more than 4 solar cells, probably 24 solar cells in order to obtain the greater voltage wired in series, correct? It's that even possible, to have all of the cells wired in series?

To use the 220V inverter I need a 12V battery, now I try to keep the cost as low as possible but looks like I need more cells for this.

[inetdog]

Standard panels use 40 or more cells wired in series. No problem except that for DIY there are than many more series connections to fail and any one failure would take out the whole panel.

[lkruper]

The goal is to show a small PV system built by me from sun to a lighting bulb, or even some 220V devices and explain how it works. Probably dumb, but I missed something and I didn't know that there's a minimum voltage to charge battery I was just considering the overall Watts power.

Here, the cells I found are like mentioned previously 0.6V 6.3A. The battery is 12V 7AH. I have to build the system to output a minimum voltage of 12V, right? does amperage matters?

I think I will have to buy more than 4 solar cells, probably 24 solar cells in order to obtain the greater voltage wired in series, correct? It's that even possible, to have all of the cells wired in series?

To use the 220V inverter I need a 12V battery, now I try to keep the cost as low as possible but looks like I need more cells for this.

If you already have the battery, you should find the manufacturer's recommendation on their web site as to what voltage is required and recommended amps to charge.

[SunEagle]

The goal is to show a small PV system built by me from sun to a lighting bulb, or even some 220V devices and explain how it works. Probably dumb, but I missed something and I didn't know that there's a minimum voltage to charge battery I was just considering the overall Watts power.

Here, the cells I found are like mentioned previously 0.6V 6.3A. The battery is 12V 7AH. I have to build the system to output a minimum voltage of 12V, right? does amperage matters?

I think I will have to buy more than 4 solar cells, probably 24 solar cells in order to obtain the greater voltage wired in series, correct? It's that even possible, to have all of the cells wired in series?

To use the 220V inverter I need a 12V battery, now I try to keep the cost as low as possible but looks like I need more cells for this.

Before you spend any more more money (since you want to keep the cost as low as possible) you really should do more research on what is needed to use solar to charge a battery and run electrical loads.

Biggest mistake most beginners make is purchasing parts only to find nothing works or worse their batteries quickly die. A solar battery system requires understanding and purchase of hardware that is "balanced" and meets the needs of running your electric loads. Hardware that is cheap, too small or too big to do their part will quickly kill the system.

Unfortunately LOW COST is not part of the formula to building a system that works.

[J.P.M.]

Before you spend any more more money (since you want to keep the cost as low as possible) you really should do more research on what is needed to use solar to charge a battery and run electrical loads.

Especially since this sounds like it's for educational purposes.

[thastinger]

The goal is to show a small PV system built by me from sun to a lighting bulb, or even some 220V devices and explain how it works..

Go buy a LED landscape light.

Seriously, why spend all that money and time to buy/build/demo a system not capable of much. You can explain the concepts (which you seem to need some research in) with a 99 cent landscape light as it has a PV cell, a battery and a charge controller circuit all built in.

[Living Large]

I'm wondering why 220V. Is this the standard voltage in your country? Do you need to have AC?

[SunEagle]

I'm wondering why 220V. Is this the standard voltage in your country? Do you need to have AC?

That was my guess on the 220v being the OP's standard single phase power.

As for needing AC... I am sure you have read enough posting on this forum where people who know very little about a solar/battery system want to build one and then immediately want to jump to powering their large AC appliances without understanding the enormity and cost of such a practice.

[Living Large]

I am sure you have read enough posting on this forum where people who know very little about a solar/battery system want to build one and then immediately want to jump to powering their large AC appliances without understanding the enormity and cost of such a practice.

The OP here said he wanted to run a light bulb and "even some 220V devices", so maybe that is what is in his mind. At 72W possibly from his solar array, those devices will have to be low power.

[SunEagle]

The OP here said he wanted to run a light bulb and "even some 220V devices", so maybe that is what is in his mind. At 72W possibly from his solar array, those devices will have to be low power.

I agree that whatever load the OP wants to run (DC or AC) it will have to be very low wattage and for a very short period of time.

[ZzZr]

Can't believe my question brought so much attention here, thanks everyone.

First, I need to mention that nothing yet has been bought. Mostly will be cheap be chinese appliances, for demonstration and experiment purposes .

I will not build the PV module anymore, it's too expensive to buy those cells right now, and also wire them, I will actually buy them, but later on, to experiment and play with them when I will have more time. For now I will just buy a 5W panel which has VMP:16.5V, which most likely will be enough to charge the 12V battery [not sure if a manual will be provided for the battery].

Regarding inverter, obviously I'm not going to power something big, just small things to demonstrate "look, we can power everything with sun power" even 220V things [my country has the 220V standard that's why I was referring to this] , yeah, I will just plug a USB charger. The inverter will be connected to the 12V battery, and get the power from there.

Here are few details I have about the products I'm going to buy for this small system:

PV module - 5W; VMP: 16.5V; IMP:0.55A; VOC: 21.6V; ISC: 0.61A
Charge controller - Rated voltage: 12V/24V; Max Load Current 10A
Battery - 12Vx7.5A
Inverter - something very similar to this one

[SunEagle]

Can't believe my question brought so much attention here, thanks everyone.

First, I need to mention that nothing yet has been bought. Mostly will be cheap be chinese appliances, for demonstration and experiment purposes .

I will not build the PV module anymore, it's too expensive to buy those cells right now, and also wire them, I will actually buy them, but later on, to experiment and play with them when I will have more time. For now I will just buy a 5W panel which has VMP:16.5V, which most likely will be enough to charge the 12V battery [not sure if a manual will be provided for the battery].

Regarding inverter, obviously I'm not going to power something big, just small things to demonstrate "look, we can power everything with sun power" even 220V things [my country has the 220V standard that's why I was referring to this] , yeah, I will just plug a USB charger. The inverter will be connected to the 12V battery, and get the power from there.

Here are few details I have about the products I'm going to buy for this small system:

PV module - 5W; VMP: 16.5V; IMP:0.55A; VOC: 21.6V; ISC: 0.61A
Charge controller - Rated voltage: 12V/24V; Max Load Current 10A
Battery - 12Vx7.5A
Inverter - something very similar to this one

I understand your experiment now that you have provided more details.

I see 2 potential problems.

1. That 7.5Ah battery will be drained within an hour if your load is more than 50 watts and you use that 300 watt inverter. Even a very small 220volt appliance will be too much for that battery.

2. That solar panel is too small and at Imp = 0.55A will take a few days to recharge your battery back up after one use.

I would use a very small wattage (< 5w) LED light in your experiment. Anything larger and you will drain the battery quickly and shorten it's life dramatically.

[ZzZr]

1. That 7.5Ah battery will be drained within an hour if your load is more than 50 watts and you use that 300 watt inverter. Even a very small 220volt appliance will be too much for that battery.

2. That solar panel is too small and at Imp = 0.55A will take a few days to recharge your battery back up after one use.

1. You're very correct, and I don't plan to use for more than 1 minute. It will be probably few seconds of load.
2. The battery will be almost fully charged when doing any demonstration. As well I was thinking to a 5W LED bulb and some phone USB charger.

Thanks for suggestions.

I'm new and I'm learning about this