How Big Is My Solar System

How To Fuse Your Solar System

Technical Representative

When hooking up your Renogy system,the best way to add protection is by using fuses or circuit breakers. Fuses andcircuit breakers are used to protect the wiring from getting too hot and alsoprotect all devices connected in the system from catching fire or gettingdamaged if a short circuit occurs. They are not necessary for the system to runproperly, but we always recommend using fuses or circuit breakers for safetypurposes. There are three different locations that we recommend installingfuses or breakers: first, between the charge controller and battery bank,second, between the charge controller and solar panels, and third would be betweenthe battery bank and inverter.

Todetermine the fuse size needed between the charge controller and battery bank yousimply match the amperage rating on the charge controller. For instance, if youhave one of our 40Amp charge controllers, we would recommend using an 40Ampfuse.

Thelast fuse that we recommend in the system would be if you are using aninverter. This fuse would be between your inverter and the battery bank. Thefuse size is usually stated in the manual and most inverters already have builtin fuses/breakers. The rule of thumb that we use here would be ContinuousWatts / Battery Voltage times 1.25, for example a typical 1000W 12V inverterdraws up around 83 continuous amps and we would add the 25% safety factor whichcomes out to 105 Amps, so we would recommend a 150A fuse.

Looking For Solar Panels

Your minimum aim is to cover as much of your household consumption as reasonably possible for a typical day. If your power consumption is 30kWh on some days, but on most days it’s 20kWh, it might not be worth adding extra panels just to cover those few 30kWh days. You could go with a 5kW solar PV system and just accept paying for more power than usual from the grid on those occasional high-consumption days.

But solar panels are relatively cheap now, and there’s an economy of scale in installing a larger system, so it’s worth talking this through with your installer to consider how big a system you could get. Typical solar PV systems installed in 2021 are at least 6.6kW in size and we think that’s a good size for most homes to aim for right now.

That said, bigger systems of 810kW are becoming more common, especially for systems that include a storage battery.

You might think it’s better to oversize your system because any excess will be exported to the grid, and you’ll be paid for it via the feed-in tariff. But the feed-in tariff for new solar PV systems is generally very low typically from four to eight cents per kWh, though you can get better deals from some energy retailers and it’s unlikely on its own to justify the cost of a larger system.

Read more: Are solar feed-in tariffs worth it?

Power usage shifting

Online calculators

Why Are There Limits On Grid

If your home is connected to the power grid, then whether you realise it or not there is a network company servicing your home. More accurately, the grid company is known as the distribution network service provider . DNSPs are by their nature monopolies, as they own & operate the physical infrastructure that delivers electricity to your home.

Things can sometimes get a bit confusing when it comes to this topic: In some regions of Australia , the network company is also the company that sells you electricity but in most cases its not .

How electricity is transported.

The electricity grid as we know it was designed to work unidirectionally electricity is generated at large, centralised generators , sent long distances over transmission lines before being stepped down to distribution lines and finally delivered to your home or business.

The original architects of our electricity infrastructure did not intend for electricity to move in the other direction. While this doesnt necessarily mean that its impossible for electricity to flow backwards, it can potentially be tricky for the networks to manage on a technological level especially when there are a lot of distributed systems all feeding back to the grid in the same area.

This is the main reason why networks put limits on system sizes, at least until such a time as the grid gets a lot smarter and better at handling bidirectional electricity flow.

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Average System Size And Power Output By Location

We know that real-world output for a given system size is affected by several factors and is constantly fluctuating. But dont worry – its possible to account for weather conditions in your area based on decades of historical data, which allows us to calculate average solar power output for a given solar system size at any specific location.

*Daily kWh generation figures can see large variations between seasons, and even from day to day.

Do note that the figures above are just averages. The amount of power generation will vary, especially if weather conditions where you live are different from the state average, or if your roof has a sub-optimal orientation or angle.

Dont worry though, you can still come up with accurate system size and production figures for your specific home – just use one of the three calculations methods we discussed earlier.

How To Size Batteries For A Solar System

Grid-tied solar doesnt work when the electricity goes out. While it is frustrating, having a grid-tied system gives you many other benefits. But were not here to talk about those. Were here to talk about how you can get electricity when the grid goes down.

As battery technologies improve, price decreases and efficiency increases. That means grid-tied solar with battery backups are becoming a more prevalent – albeit still expensive – option. With the proper setup, you can install batteries along with your new solar system, or add batteries to your existing system. However, these systems arent meant to cover 100% of your normal usage, and you should take time to really think about which devices and appliances need to be powered when the lights go out.

So where do you begin with determining how much battery storage you need? Like so many other answers youll find on the internet, were going to say it depends. But were here to help clear that up. Well show you what you need to think about when determining what size battery system youll need, and well also give you some examples of how much you can power with batteries powered by solar.

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Or Will You What Can Affect Solar Panel Output Efficiency

The Standard Test Condition rating is based on ideal conditions converting the suns energy into power. But the solar system itself is not 100 percent efficient in converting the energy into power.

• A solar system requires an inverter to convert the Direct Current power the photovoltaic cells receive from the sun to Alternating Current power used in our homes. Power is lost as it goes through the inverter, which can be a single inverter per system, or a single inverter per solar panel. It is estimated that about three percent of electricity is lost passing through the inverter.
• Different materials used to manufacture the cells can resist the flow of electricity as can resistance passing through the cables.
• Inevitably, solar panels will pick up grime and dirt from the atmosphere, blocking full sunshine.
• Temperature can effectively create power losses as well. While it seems that a hot, sunny local would be ideal, the fact is that the STC is based on a temperature of 25 degrees Celsius . The flow of electrons across the photovoltaic cells is not as efficient at higher temperatures. All in all, solar companies estimate a de-rating factor of around 20 percent.

Be aware that system sizes are calculated inversely in the United Kingdom and the United States.

Thus, a typical 1 kWh system in the UK is estimated to produce 850 kWh unit per year, a 2 kWh would create around 1,700 kWh units per year and a 5 kWh system is estimated to create 4,500 kWh .

How Many Hours Of Sunlight Can You Expect In Your Area

The peak sunlight hours for your particular location will have a direct impact on the energy you can expect your home solar system to produce. For example, if you live in Phoenix you can expect to have a greater number of peak sunlight hours than if you lived in Seattle. That doesnt mean a Seattle homeowner cant go solar it just means the homeowner would need more panels.

The Renewable Resource Data Center provides sunlight information by state and for major cities.

Now multiply your hourly usage by 1,000 to convert your hourly power generation need to watts. Divide your average hourly wattage requirement by the number of daily peak sunlight hours for your area. This gives you the amount of energy your panels need to produce every hour. So the average U.S. home in an area that gets five peak sunlight hours per day would need 6,000 watts.

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How Many Solar Panels Do You Need To Power Your House

Example Sizing solar panel PV systems

How many solar panels and their power rating would be needed for a fixed solar system to cover the energy consumption of an average U.S. home?

Lets say the house is in Burns, Oregon USA, with an average electricity consumption per day of 33 kWh.

Checking the site Global Solar Atlas, we see that the irradiation in this location is 5.83kWh/m2/day.

Use historical irradiance data to find suns energy in your location

• Geographic Location: Burns, Oregon, USA
• Average daily energy consumption: 33kWh/day
• Irradiation for Burns, Oregon is 5.83kWh/m2 per day

PV System Losses

I previously said that system losses can be 23%, but they can also be higher. Ill use 30% as the overall system loss, to make sure I dont underestimate the number of solar panels to cover the homes energy needs.

With 30% losses in mind, the energy needs are:

33kWh/day x 1.44 = 47.5 kWh/day load.

Now to take into account the efficiency of inverter, which is about 96%.

The power to be supplied to the inverter = 47.5/0.96 = 49.5kWh/day.

The average daily irradiation is 5.83kWh/m2

49.5kWh/day of power can be produced by:

49.5/5.83kWh/m2= 8.5kW or 9kW of solar panels working at 100% capacity rating.

To find the number of solar panels needed, divide the wattage needed by wattage of each solar panel :

Number of panels needed = 9kW/300 watts per panel = 30 solar panels.

How To Calculate Solar Panel Size Needed

If you are looking into purchasing solar panels to be installed on your roof, then you are in for a fantastic experience. They are a brilliant way to provide energy for your home and lower your annual energy bills in one go. Plus, they are environmentally friendly and require hardly any maintenance. However, before you buy, it is important to have a rough idea of the panel size and amount that you will need. Make sure you consult a professional and accredited installer about this, but this page can act as a rough guide.

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Solar System Sizing Tool & Calculator

The following tool is intended to assist users to calculate a size of an entry-level solar system for home use, which includes the solar panels, inverter, batteries and user load. Products listed and its information is that of The Sun Pays solar products. The tool utilizes product information such as efficiencies in order to give a more realistic solar system design.

Disclaimer: The tool is intended to be used as a guide. The Sun Pays can not be held responsible for the outcome of the results of the tool. It is still the end-user’s responsibility to confirm if the selected equipment will be suitable for the user’s needs or to obtain professional help from accredited installers.

Feedback: The solar sizing calculator is still a work in progress. At the current stage, the solar sizing calculator is only for 48V solar systems. For requests and feedback, please contact .

How to use the tool:Step 1: Fill in the user load. A list of common items is provided. Choose the number of hours the items in used in the day and nightStep 2:Choose the battery type and configuration. Step 3 A: Choose the solar panel configuration. The panel configuration will be the panels in series and how many series arrays will there be in parallel.Step 3 B: Choose the type of solar panels.Step 4: Choose the inverter type.Step 5:Review the feedback and make changes to the system setup if required.

What Does Solar System Size Mean Exactly

In the solar industry, the term solar system size is used to describe a solar panel systems capacity to produce electricity.

A solar panel system sized 300 watts is one that can produce 300 watts of electricity, while a system sized 6 kilowatt solar system will produce 6000 watts – under standard conditions.

Lets break down the key terms used here:

• Standard conditions: These are the specific conditions required for solar panels to perform at full capacity, or peak output. The solar cells should have exactly 1000 watts of sunlight per square meter shining on them, and they should be operating at a consistent temperature of 77F° . These specific conditions, recreated in a lab, are technically called Standard Test Conditions .
• Watts: Watts are a unit of measuring electric output. When we are discussing solar panel or solar system size, we are referring to watts of Direct Current electrical output. .

Now that you know these terms, solar panel spec sheets and solar system quotes will make more sense.

For instance, youll see a solar panel described as rated 300 watts of DC output at STC in laymans terms, wed call it a 300-watt panel. And when we put 20 panels with this wattage together to create a solar system, we get a solar system thats 6 kilowatts in size!

Now that we know what the term solar system size measures, lets compare the three methods we can use to calculate it.

Learn more: How much output do you get from solar panels?

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What Size Solar Power System Is Best For You

To get the most out of a solar power system solar installers can make a recommendation for a system size that will best suit your needs. Ultimately, the choice is up to you.

When filling in the My Solar Quotes request for 3 free quotes form, you can choose the option from the drop-down list that states ‘I don’t know – please suggest the best system size for me’ . Once your quote request has been received from solar installers they will take into account how much power you currently consume and the time of day you consume it, to determine a suitable system. Roof size and your personal budget are other factors to consider when making your decision.

How Much Solar Power Do I Need

My advice on solar power system sizing has changed over the years due to the cost of solar panels continuing to reduce over time.

This video explains the system size providing the best bang for buck for the typical Australian household:

Spoiler alert if you dont feel like watching, my advice on system sizing is: if you have reasonable electricity consumption and a decent feed-in tariff, install as many solar panels as you can fit and afford.

This article digs a bit deeper into why my advice is to fill your roof rather than a specific size and shows how to use my nifty solar calculator to see what a solar system can do to your bills.

But first some basics.

The size of a solar power system is described by total panel capacity, expressed in kiloWatts .

A Watt is a basic measure of electrical power, and the kilo means there are 1000 of them. i.e. 1 kW = 1000 Watts

For example a system made up of 18 x 370W solar panels = a 6.6 kW system.

When buying a solar power system, its common for installers to quote on oversized systems.

The linked article goes into more detail, but in short you get huge bang for buck by putting on 33% more panels than an inverter is rated for.

This is why 6.6kW solar systems, using 5 kW inverters, are king in 2021 they represent a sizing sweet spot for what the typical home can fit on the roof. Theyre also usually the maximum size a Distributed Network Service Provider will allow on a single-phase home .

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How To Calculate The Size Of Your Solar System

One of the more appealing aspects of going solar is the notion that a solar system will automatically replace your entire electric bill. However, having your own energy supply doesnt guarantee that it will generate enough power to cover 100% of your consumption. These calculations may seem complicated, so in this article well explain how to calculate the size of your solar system based on your actual consumption.

Understanding the difference between your electricity needs and the capabilities of your system can prepare you for the reality of post-solar electric bills. Having a personal energy source does not mean that it is an unlimited supply of energy, but having the right system size and understanding your energy consumption can help you take steps to optimize your systems efficiency.

A solar system is sized according to your past 12-month energy consumption plus the solar capacity of your home.

The offset is calculated on an annual basis . If you divide your total yearly solar production by your total yearly consumption, you may not come close to 100% offset depending on the size and efficiency of your system, and the homes location in relation to the sun.

The good news is that photovoltaic systems are becoming more and more efficient, and with a few considerations you may be able to achieve optimal offset.