HigherVoltageSolar

Discussion in 'General Electronics Chat' started by Caps18, Jun 17, 2013.

1. Caps18 Thread Starter New Member

Jun 17, 2013
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(Title should be: Increasing voltage of multiple solar panels ), if the bug is that the title has to be under 20 characters. I hope that the blank page I have been getting when submitting is an error and not going into the mod queue.

Hi,

I am wondering if you guys have any suggestions about how I can increase the voltage of the solar panels on my roof without blowing them up.

The little backstory is that I purchased some solar panels that were rated for 22.8V (short circuit), and the microinverters were supposed to start up at 22V. Well, once it gets warm in the mornings here, the solar panel voltage doesn't get above 21.2V and they aren't turning on regularly. The solar panels drop in voltage as they produce more power when they do turn on as the temperature goes up, but I need them to have a higher voltage. While keeping the amps down so the watts aren't too high.

Is it feasible or possible to boost the voltage up to the 24-32V range by adding another solar panel that has a higher voltage, along with dividing the amps between 4 (or 8) panels so they don't go over 10.0A? Or in other words to keep the Watts under 230-240W?

I have attached a diagram with no diodes or other electronics on it, but to describe how I would envision this working, but I don't know if it is the right concept or not. The bottom solar panel can have different specs if needed. Or is this a crazy idea?

Thanks!

Jun 17, 2013
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3. Kermit2 AAC Fanatic!

Feb 5, 2010
4,158
1,125
Your higher voltage panel will end up supplying 100% of its capable power output. kinda like adding a 12 volt battery to set of 6 volt batteries. The higher voltage source will 'overpower' the lower voltage one.

The single higher voltage panel will increase your overall voltage level mainly due to it supplying more current to your load and thereby lower the overall current demand from the lower voltage array, and allowing its voltage to rise accordingly.

This is not a good way to proceed. I recommend you add additional units like the ones already installed(16-21 volt panels) and not ones with such widely differing voltage output levels.

4. ErnieM AAC Fanatic!

Apr 24, 2011
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1,827
In a series circuit each member carries the same current. So when increasing the voltage you want to use something that can produce that current, and with a solar panel that element is (que inspiring music) ANOTHER solar panel.

Place units in pairs to double their voltage output. First check if your micro inverter will handle that voltage (and look at a sunny winter day for the maximum voltage).

However,the basic problem seems to be your micro inverter isn't designed to work with these panels. Did you design the system yourself, or did your installer do it? If your installer did... sue!

5. wmodavis Well-Known Member

Oct 23, 2010
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To increase voltage - wire so voltage sources are in series adding.

"solar panels that were rated for 22.8V (short circuit)" - Huh? Not possible!

"the microinverters were supposed to start up at 22V" - Sounds like a bad system design. Best to use inverter that works with your PV modules rather than re-kludging to get something else that doesn't work.

My 14 PV modules are in series to provide ~520Vdc (OC) and inverter MPP is 230 to 500 Vdc. Inverter runs even under very low light condx and even with high (near 100 deg) ambient temp. Designed to operate worst case not on 'best wish' case.

I think you are trying to use with inappropriately matched components and won't fair much better unless properly designed and configured.

6. Caps18 Thread Starter New Member

Jun 17, 2013
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Thanks for all of your advice. But, I have a few more questions.

I would like the higher panel to supply 100% of it's power, but I don't know if it would be possible to raise the voltage of the other panel... and while I don't know what would happen to the amps.

With a battery, a 12V, 7Ah hooked up with a 6V,3 Ah one, what do you get? 18V and 5.6 Ah or 18V and 3 Ah? Do solar panels connected to an inverter act differently?

There is a maximum voltage rating and a maximum wattage rating that would be exceeded if I tried that.

It would be ok if the current was lower and the voltage went up. Or if I could somehow divide the extra current from the high voltage panel among the other ones.

I'm not suing, lawyers are what is wrong with society, and it won't fix the problem.

Yes, mistakes were made. Specs that we assumed would be fine were not. Now it is a question of how do we fix the problem with the best possible outcome for a little money. If I need to add 1 or 2 more panels to do it, it would be ok.

I would like to be able to come up with a basic design or concept that might work before I go to the 'professionals'.

It is good to know that your panels can run at much higher voltages in series. But the vast majority of people use the same type of panel, and don't try to spread out the power to multiple panels. Why does it feel like I am the first person in the world to ever have to deal with this problem...?

7. Kermit2 AAC Fanatic!

Feb 5, 2010
4,158
1,125
Your scheme may work as you desire. It is not 'best practice', but then it is not going to blow up or melt down either.

Your are essentiall putting one panel in series with 4 different outputs, according to your drawing. The limiting factor will be current in each of the outputs.

If your outputs are now being overloaded(just barely), then adding the one extra panel will provide you with some extra wattage that may do exactly what you want it to.

The single panel will behave differently according to how many different loads are connected and how much each output is individually loaded. overloading a single one of the four will result in a much lower 'boost' voltage being delivered by your extra panel.

You are at the point now, where, you pretty much have to try it and see if it will help you or cause you more problems.