solar panels mounted on roof

11 Frequently Asked Questions And Answers About PV Systems And Storage

Having your own power supply is new territory for many homeowners. We can see from the many questions we are asked that interest is growing massively.

We have collected the most frequently asked questions from our customers and would now like to answer them in detail here. We hope that our answers will help you. We have been dealing with the topic of solar energy and alternative energy sources for many years.

If you have any further questions, you can of course contact us as usual by email or our contact form.

If I am now interested in my own power supply but have no idea yet: What is the first step?

First I would define the budget and then consult an installer relatively quickly. The installer will immediately be able to tell you an approximate investment amount, how much power in kilowatts (kW) he will get on the roof, i.e. how much electricity you will generate. You can use a rule of thumb to assess whether the investment is worthwhile. You add the investment in the system to the electricity costs for the residual electricity supply and deduct the income from the feed-in tariff of currently around 5+10 cents per kilowatt-hour (depending on the region). Compare this result with your current electricity costs. So the annual electricity requirement times the price for a kilowatt-hour of currently around 10-20 cents.

How much does a PV system and storage cost?

On average, typical single-family households spend around 16,000 dollars for the combination of PV systems and storage. How high the investment is in individual cases can be answered just as little as the question of what a red car costs. Depending on the size of the system, the complexity of the installation, or “disturbing factors” such as shading, bay windows, and dormers, it becomes more expensive or affordable. If I had to generalize anyway (emphasis on would), I would calculate $1,200 to $1,600 per kW of power for a photovoltaic system. But that would already include the installation. What you also have to see: 20 years ago you would have spent 8,000 to 9,000 dollars per kW, but you would have received more feed-in tariffs. Otherwise, nobody would have done it back then.

That means that because the feed-in tariff is falling, should I use as much of my own electricity as possible myself?

Absolutely, that’s the basic drive. First, it feels good to use homemade, second, it’s a lot cheaper. On average, a self-generated and directly consumed kilowatt-hour of green electricity costs you around 50% less than a kilowatt-hour from the grid (again, it depends on the individual region). But you can also do a lot in terms of price when it comes to residual electricity requirements.

When is it worth buying a power storage unit for a new or existing photovoltaic system?

Without storage, you can use about a third of the electricity you generate yourself, you feed the rest into the grid and receive a feed-in tariff of currently around 5-10 cents. If you now have high electricity consumption due to large electricity consumers such as a heat pump and an electric car – let’s say 10,000-kilowatt hours a year – then at the current kilowatt-hour price of around 15-20 cents without a PV system and storage, it will be cost you 3,000 dollars per year. With a photovoltaic system for only 2,000 dollars, a storage system adds only around 1,000 dollars.

So the combination of photovoltaic systems and storage is all the more worthwhile if I have large electricity consumers?

Exactly. The more you consume, the more you save. If there are only two people in the household with a standard consumption profile of around 3,400 kilowatt hours per year, investing in a storage system would not necessarily be worthwhile. But things would look very different if the couple bought an electric car.

In addition to self-consumption, the term self-sufficiency, i.e. independence from the power grid, is often mentioned. This refers to the proportion of the total electricity requirement that can be covered by your own generation. How independent can I typically become?

With a normal solar panel unit and energy storage unit, you can do about 60% on average. There are also sunny days when you will reach 100% with a large photovoltaic system and direct consumption. There are people who strive for this all the time. They are primarily concerned with the feeling of independence and less with the question of when everything will have paid for itself. They’re fulfilling a dream. Just like with other purchases, it doesn’t matter to you whether it pays off now or whether it will pay for itself. You just want that.

How do I achieve a good self-sufficiency value?

On the one hand through high performance of the photovoltaic system and storage, on the other hand through your behavior. You have to use the electricity very consciously, for example switching on the large electricity consumers exactly when the system is currently producing a lot of electricity or the storage is full. A typical example is washing clothes: if the weather is bad today, you just do the laundry tomorrow.

It is clear that a photovoltaic system belongs on the roof. But where should the storage ideally go? Sometimes you see pictures on the internet, there they stand like a trophy in the living room. Is this really a good place?

The storage should be in the basement or in the garage because the inverter whirrs like a refrigerator. Ideally, the storage tank should be located where people or pets do not stay for long. In addition, the room should be neither too hot nor too cold. For example, a garage where you can see your own breath in winter is not a good place. At extreme temperatures, the batteries go on strike. In the case of electric cars, on the other hand, the batteries can provide the hoped-for performance even in winter because they are automatically heated.

Can I generate green electricity all year round?

In any case. Many think that operating a photovoltaic system is only worthwhile in the summer when extreme heat reduces the efficiency of the system. This is only made up for by the fact that it is light for a long time. It’s the light that matters, not the temperature, so you can generate a lot of green electricity even on a cold January day.

How do I know that the electricity I use comes from my own PV system?

You use the electricity from your PV system directly. It is different from the surplus that you store in your attic. This surplus goes first into the network. But the same amount goes back into storage. On the balance sheet, it’s still your power.

But not physically, right?

No not that. But the decisive factor is that you have generated green electricity – in a quantity for which no electricity from coal or nuclear power had to be generated. So your excess electricity is used by someone else.


Using solar power is a great way to save money and protect the environment. Of course, you first have to invest something in your new solar system. But depending on the volume generated, your new solar power system will quickly pay for itself.

The development of solar modules continues and modern solar modules are becoming more and more efficient. In this way, you can generate a lot of electricity in a small area, which you can use in your household. You can also store unused electricity and use it when the sun isn’t shining.

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