ᐅ Planning Photovoltaic Systems – Potential Retrofit of Battery Storage
Created on: 12 Feb 2018 10:04
J
jx7
How do you plan a photovoltaic system that might later be equipped with a battery storage, if rising electricity prices and falling battery prices make this economically viable?
Option 1:
- Design and plan the system including storage, but simply leave out the battery for now.
- Very simple retrofit option: only connection of the battery required.
- However, as long as no battery is added, the system is oversized because there are too many panels on the roof.
Option 2:
- Design and plan the system including storage, but leave out the battery and install fewer panels on the roof.
- Retrofit option available by adding the battery and installing additional panels.
Option 3:
- Initially design the system completely for operation without storage (saves costs).
- Retrofitting later is somewhat more complex.
Where do you see the best option when weighing the three cost factors:
- Installation costs of the system (without storage)
- Economic efficiency of the system operating without storage
- Possible costs of converting to operation with storage
4-person household, gable roof surfaces facing west and east, household electricity consumption 5200 kWh per year, geothermal heat pump
Option 1:
- Design and plan the system including storage, but simply leave out the battery for now.
- Very simple retrofit option: only connection of the battery required.
- However, as long as no battery is added, the system is oversized because there are too many panels on the roof.
Option 2:
- Design and plan the system including storage, but leave out the battery and install fewer panels on the roof.
- Retrofit option available by adding the battery and installing additional panels.
Option 3:
- Initially design the system completely for operation without storage (saves costs).
- Retrofitting later is somewhat more complex.
Where do you see the best option when weighing the three cost factors:
- Installation costs of the system (without storage)
- Economic efficiency of the system operating without storage
- Possible costs of converting to operation with storage
4-person household, gable roof surfaces facing west and east, household electricity consumption 5200 kWh per year, geothermal heat pump
jx7 schrieb:
How do you plan a photovoltaic system that might later be equipped with a battery storage, if rising electricity prices and falling battery costs make it economically viable?
My suggestion (based on many years of experience in a different industry that has been intensively involved with electrical storage technology for some time): Option 4 – forget about storage. The hope for falling prices will not materialize. With continuously increasing demand, driven especially by the transport sector alone, we will never see significantly declining prices.
Regards
D
Deliverer15 Feb 2018 11:43derSteph schrieb:
Option 4 – forget about storage. I would agree with that.
derSteph schrieb:
The hope for falling prices will not be fulfilled. With continuously increasing demand, driven primarily by the transport sector alone, we will never see significantly declining prices. However, experience (and studies) from the past ~20 years contradict this. Prices have been steadily and quite rapidly decreasing, inversely correlated with the rise in electric vehicle sales.
Regarding prices, I believe both of you are right but are talking past each other. Certainly, technological advances will gradually reduce production costs. However, as we approach a profitability threshold, demand will rise sharply, which may not be met quickly by production capacity. The result: prices won’t drop as fast because order books are full and profit margins increase. This is exactly what we are seeing with construction costs since interest rates have been so low.
Fuchur schrieb:
Regarding prices, I believe you both are right but talking past each other. Certainly, technological advances will gradually reduce production costs. However, as we approach a profitability threshold, the demand curve will steepen sharply, which may not be met quickly by production capacity. The result: prices won’t fall as fast because order books are full and profit margins increase. This is exactly what we see with construction costs since interest rates have been so low.It couldn’t be summarized better. That perfectly matches my assessment. Thanks.Best regards
G
garfunkel15 Feb 2018 16:57I have calculated this several times before...
It’s only worthwhile if the gain is marginal. I also calculated pessimistically to realistically, but still.
By now, I would say a system size optimized for about 5 hours of consumption is "ideal."
Ideally, the system would only produce as much as is continuously consumed. This would mean minimal installation costs and 100% self-consumption.
However, self-consumption is usually not high enough to justify the installation work on its own.
But if you can store about 5 hours of production with a battery, you may be able to cover "peak times."
For example, charging in the morning and consuming at midday, then charging again in the afternoon and consuming in the evening, plus current feed-in to the grid.
This approach might allow you to match the highest consumption periods with energy production.
That way, you could probably achieve the best price-performance ratio.
You really need to calculate it carefully.
It’s only worthwhile if the gain is marginal. I also calculated pessimistically to realistically, but still.
By now, I would say a system size optimized for about 5 hours of consumption is "ideal."
Ideally, the system would only produce as much as is continuously consumed. This would mean minimal installation costs and 100% self-consumption.
However, self-consumption is usually not high enough to justify the installation work on its own.
But if you can store about 5 hours of production with a battery, you may be able to cover "peak times."
For example, charging in the morning and consuming at midday, then charging again in the afternoon and consuming in the evening, plus current feed-in to the grid.
This approach might allow you to match the highest consumption periods with energy production.
That way, you could probably achieve the best price-performance ratio.
You really need to calculate it carefully.
garfunkel schrieb:
I have calculated this several times before...
It’s only worthwhile by a small margin at best. I also worked with pessimistic to realistic assumptions, but still. I would like to see that calculation. There are plenty of examples from buyers of these storage systems. You still have the problem that in summer, more electricity is generated than you need (and than the storage can hold), and in winter the storage is empty and production doesn’t meet the consumption.
In the end, the results were all quite similar. Let’s assume pessimistically 30% self-consumption without storage, and optimistically 60% with storage.
This means 30% of the consumption is drawn from the storage instead of the grid. The savings are about 12.5 cents per kWh. Assuming a household consumption of 4000 kWh, the storage saves us 4000 * 30% * $0.125 = $150 per year.
Over a battery lifetime of 20 years, that amounts to $3000. It will take a long time to get a sufficient storage system for that amount. And then you have only recouped your investment, without any profit.
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