How does solar cells work in a solar power plant?

An offgrid solar power system actually works quite simple. You need solar panels, a charge controller and a battery. Actually there is more to it …. and so anyway, yes there is.
If we dig a little deeper to find out how does solar cells work in detail, so there are many things that must be in place, partly to make it work and partly to make it work well.

How does solar basically work ?:

A solar cell makes light into direct current (DC). The more light that shine on the solar cell, the more power are produced.
The power effects listed on a solar panel, shows how much the solar panel can produce, when the sun shines directly on the solar cells and not a little from the side or from above (a solar panel is made of multiple solar cells in series). So it is a number that is only true when the sun shine it’s best and the solar panel is placed in just the right angle to the sun.
When it is heavily cloudy the output from solar panels drops to 10-20% of the nominated effect. This is one reason you need a battery, that can store power from sunny days to rainy days.
In the production of power per day, the solar in July produce the bast of all year (on a standard year), let’s call it 100%, while in December there will be a production much lower. Depending on where in the world you are. And it will be opposite in the southern hemisphere.

Season for solar cells?

It is necessary to determine at what time of year you will need solar power. On a boat or a caravan, it will often be only for summer use and thus solar are a good solution. But if you also have the power need in the winter, you must have either a lot of solar and a large battery or you need to find an additional power source. A wind turbine has the effect in northern Europe that it produces much more power in the winter than it does in the summer. Can you see idea combining solar and wind??

Shadow of solar cells

Is it important whether there will be a small shadow on the solar cells? Yes! It is very important because a solar panel is made up of solar cells in series and no chain is stronger than its weakest link, so if there is shade on a solar cell, it will be pulling the rest of the solar cells in the chain down.
To avoid shade on one solar panel drags other panels down, it might be smart to connect the panels in parallel (there can be other reasons that requires you to run serial or parallel!), as the shadow of one panel do not destroys the whole production, but only production for one panel.
On the other hand there may be an advantage in that the panels are connected in series, because the voltage reaches a production level faster in the morning (requires MPPT charge controller) and lasts longer in the evening. But it requires that no shadows fall on the panels at all.

Here is a video with a test of what shadows does to a solar panel and whether you should choose serial or parallel connection. You can use the video to make up your mind. It is not in any way scientific 🙂


Solar panels angle to the sun.

The solar panel should preferably face directly at the sun at any time, but that’s very rare in practice. It requires mechanical devices moving the solar cell over the day and it can rarely pay back.
So to get as much power as possible out of the solar panels, they must turn to the south and the optimum angle to the horizontal depends on where in the world you are.
With this calculator you can see what it will mean for you and your output. The calculator takes into account where you are and your adjusted angle to the South and several possible angles relative to the horizontal:

What does a charge controller?

How does solar cells work with the charge controller? The charge controller is there to protect your battery. There is an the opportunity to join very small sizes solar watt directly to a battery, but we would always recommend that you use a charge controller. In more than 98% of the cases, it is directly necessary!
If the charge controller is of a decent quality and the best technology (MPPT) it will be able to get more power out of your solar cells and charge adjusted on your battery depending on the charge status of your battery. So it is important that you choose a good quality charge controller, as it will give a greater yield and your expensive batteries will last longer.

The regulator also protects the battery from discharging more than it is designed for and ensures that no current flows back to the solar at night.

It’s not here you want’s to be cheap ;o)

Solar batteries

The battery is an expensive part of your system and you can destroy them in a short time or you can take care of them and have them in 10 years.
Without going into deep battery details here, for that you can read about elsewhere on this site, it is in generally important that you choose a type of battery that fits your usage pattern.
Roughly speaking, there are starter batteries like the ones you know from your car/boat, it needs to be able to deliver a high starting current for a short period and the Deep cycle batteries can deliver a lower current over a longer period. These deep cycle batteries are typically used in conjunction with offgrid plant.
Deep cycle batteries have the advantage that they can be discharged by 50% without taking significant damage (we recommend that you do not drain more than 30%  everyday life), where starting batteries will be damage after only 10% discharge.
Lithium-ion batteries can discharge more, but is however more expensive.
So find out your consumption pattern before you buy your batteries.
Many of our charge controllers can priority the charge on 2 battery banks, so you always have power on your starter battery and after topping op the starter battery, you get power to your consumption battery (deep cycle).

So now you got the answer to: How does solar work in a offgrid plant.

You are welcome to find more explanations about offgrid plant on our site.