32
votes
Accepted
Why am I offered a 5 kW inverter with a 6.6 kW solar installation?
It could be that the system will spend such little time providing above 5 kW, once shading and losses are taken into account, that it's not worth the cost of getting the next-largest inverter.
...
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21
votes
Why am I offered a 5 kW inverter with a 6.6 kW solar installation?
Standard Test Conditions vs Real life
Photovoltaic panels are rated at "Standard Test Conditions" (STC):
Irradiance = 1000 W/m²
Cell temperature = 25°C
Air Mass = 1.5
Those conditions are achieved ...
- 311
14
votes
Why am I offered a 5 kW inverter with a 6.6 kW solar installation?
Solar systems are rated at peak power. It's normal for inverters to be rated less since you will very rarely have ideal conditions to reach peak power. For example, my inverter is rated at 80% of peak ...
- 241
9
votes
Which battery is best for solar power?
There is no "best battery." There are different kinds of batteries for different applications. Here are some things to consider,
What voltage do I want? (Most DIY projects pick 12V because they want ...
- 676
9
votes
Why is solar energy so expensive?
It is not, necessarily
The initial capital cost of a plant is not the same thing as its lifecycle costs. The best way to analyze the cost impact of an energy source is to look at the total expected ...
- 1,067
9
votes
Why am I offered a 5 kW inverter with a 6.6 kW solar installation?
There already are some answers addressing the fact that you probably will not reach or will rarely reach the rated power of your panels. That explains why you don't need a higher rated inverter. Now, ...
- 191
8
votes
Accepted
What is the amount of silicon in a 1kw panel?
Fthenakis has published more on the subject than anyone, to my knowledge. His LCA lists a whole bunch of factors, but it's roughly 1.5kg of silicon in the PV itself.
But a module also has 16.1kg of ...
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8
votes
How does the solar industry fund itself?
Your first sentence is incorrect, as per the very chat discussion you've referenced: the sales price for panels is more than the cost of the panel's components.
The second sentence is also incorrect: ...
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8
votes
Accepted
Can 140 square miles of solar panels power the US?
Summary
No, that's way too little. I think "140 miles square" has got mangled into "140 square miles".
Running the numbers
Following on from one of Elon Musk's presentations, which ...
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8
votes
Angle of solar panels on flat roof
Oh yes it could be worth arguing about, but only if you have huge roof area and very few panels. With roof fully covered by panels, they should be flat.
Generally, if production is limited by panel ...
- 4,786
7
votes
How can I cheaply evaluate how much solar energy I can collect?
A simple short term test like the one you are thinking about will reveal little information. Many factors affect the output of photovoltaic cells.
Results from a cloudy day will differ those for a ...
- 3,517
7
votes
How much irradiation from the sun is required to generate solar power?
Solar Irradiance
The amount of energy striking the earth from the sun is about 1,370W/m2 (watts per square meter), as measured at the top of the atmosphere. This is the solar irradiance. The value at ...
- 11.8k
7
votes
Accepted
Are there solar panels that can survive extreme temperature changes?
Effects of extreme temps on solar panels
This answer on Chemistry.SE lists the three major factors which lead to solar cell degradation:
Temperature
UV exposure
Mechanical damage
...
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6
votes
Converting from W/m² to kWh/m²/day
If your data is minute-by-minute then that's exactly what you need to do.
Adding all the minute-by-minute W/m² figures for a day (you should have 1440 of them, so use a spreadsheet or script) will ...
- 2,116
6
votes
Accepted
Determine the solar installation size based on W/m² solar irradiance data
The conversion of light into electricity happens pretty much instantaneously. Well, it takes time, but such a short amount of time that we can't perceive it without some serious instrumentation.
So ...
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6
votes
Accepted
Is a solar cell phone charger a sustainable choice?
The best article I could find which addresses this question is "Life‐Cycle Assessment of Solar Charger with Integrated Organic Photovoltaics".
Their conclusion: Because of the complicated ...
- 11.8k
6
votes
Is Tesla Powerwall a good investment?
No it is not. Your calculations of 13year ROI is based on the assumption that charging the power wall is free during the day time. It is not.
Depending on your locale, either you need to factor in ...
- 380
6
votes
Pros and cons of solar panels over a parking lot?
Yes, from a sustainability point of view it's better to place solar panels over parking lots because
You save trees that can continue to absorb CO2 and provide a home for insects and possibly other ...
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6
votes
Why am I offered a 5 kW inverter with a 6.6 kW solar installation?
In some jurisdictions (like Flanders, Belgium), you have to pay a fee based on the maximum power your inverter can deliver to the grid.
As EnergyNumbers notes, slight undersizing won't necessarily ...
- 161
6
votes
Any way for microinverter PV array to power a house when the grid is down?
tl;dr: Because of how the grid and your inverters work, it's unlikely that there is a solution for your current system. You will either need to set up a communication network with your microinverters ...
- 11.8k
6
votes
Accepted
What is the most economical and convenient house battery type?
Lithium-Ion electric car batteries would do the job, but they are too expensive and I am not sure about their lifetime. A pack of ordinary lead acid car batteries seems to be a more affordable ...
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5
votes
How large a solar panel would I need to electrolyse 1 liter of water?
The flippant answer is "it depends how long you're prepared to wait". But, let's assume that you want to electrolyse a litre of water an in hour.
You've identified above that the energy needed to ...
- 3,690
5
votes
Is it cost effective to use a solar panel in an apartment if I have a low electricity bill?
The amount of power you consume/power costs are surprisingly unrelated to the cost effective-ness of solar power. To be more accurate, they are "slightly" related.
When you install a solar ...
- 191
5
votes
Can solar panels be recycled?
Yes, solar panels can be recycled -- in Europe this is required by law, and technology exists and is quickly being improved to facilitate this.
Legal requirements
In Europe, recycling of solar ...
- 11.8k
5
votes
How can I cheaply evaluate how much solar energy I can collect?
You are much better off using one of the "solar calculators", specifically one that uses actual data from installed systems. You might get lucky and find one of the tracking sites has an install near ...
- 1,307
5
votes
Fusing a Solar (PV) Panel
There is no benefit to having an extra fuse at the solar panel. The fuse at the charge controller end is recommended (an in some jurisdictions a requirement).
From https://www.boats.com/how-to/solar-...
- 203
5
votes
Is solar energy the best renewable source of energy?
The validity of your assumptions depend very much on your location and on the amount of energy you want to generate. Some small-scale solutions do not suffer from the same drawback as large-scale ...
- 14.5k
5
votes
Accepted
How to attach more sources of energy to your charge controller
If you have a single-string MPPT charge controller, then you should not even think of trying to combine your two generators (i.e. PV array and wind turbine) onto a single input and feeding that in.
...
- 2,804
5
votes
Accepted
Cost benefit analysis of a PV array with racking to set optimal angle, vs a larger array
According to the New Zealand Ministry of Business, Innovation, and Employment (pdf), the average home in New Zealand uses 7,046 kWh per year, and pays a rate of $0.2879/kWh (NZD).
I used this as a ...
- 11.8k
5
votes
How to consume all my photovoltaic electricity locally?
Maybe my answer is naive, but have you thought about a battery like the Tesla Powerwall? Storing energy during daylight and using at night increases dramatically the auto-consumption rate (~98%).
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Only top scored, non community-wiki answers of a minimum length are eligible