Some people think that a solar panel can run something well this can be a mistake, others get it wrong in that they are no good and well there is some sense that there is a middle ground.
Solar panels are DC power this means the power is straight and not wavy in the most basic of terms, most people know AC, but they dont really know the difference between AC and DC power.
Direct Current (DC): In DC current, electrons flow in a steady, constant direction. This is like water flowing continuously through a pipe. Examples of DC sources include batteries, solar cells, and fuel cells.
Alternating Current (AC): In AC current, the direction of electron flow periodically reverses. Imagine a wave where the water moves up and down instead of flowing steadily in one direction. The voltage also alternates along with the current. This is the type of electricity delivered to homes and businesses through power lines.
We are familiar with AC as this is in our homes and for the most part this was decided due to the fact that AC power can be transmitted further than DC, so getting the power to the home is much easier if you can have longer transmissions and less power stations that can only service a small area.
A lot of items within the home actually run on DC power. If you have a item with a power brick, this usually converts the AC to DC, inside the TV or screens, they are DC and some newer washing machines are also DC as well as host of other things, but most AC things can be DC things, but they have made AC the main stead as that’s what comes in from the grid, but fairly often you can buy the same AC items in DC form.
Solar is DC and therefore you could run DC items from a panel but its not straight forward.
Solar by nature is a up and down power source which can mean you are making 700w one second and 80 the next, so running anything where the power moves around could be very problematic.
Grid tied solar suffers from the same issues.
As you can see in the above image, the power is up and down and my home has a load around 400watts.
Every time i go above the red line on a grid tied system; I export the power to the grid, and likewise when its below the red line, I am paying for power from the grid to make up the shortfall.
We need to look at this a different way too. If we had storage, each time the power goes over the load, its stored and then when the solar power is below the 400w, we draw the power from the storage rather than the grid. This is how a hybrid solar system works and why having a battery for energy storage is important.
We now move on to voltage as this can be a mistake made by many when starting out with solar.
The solar panel voltage differs between panels, you may have a “12v” panel and 24V panel and high power panel around 50 volts.
The 12v panel is around 18volts, the 24 volt panel is around 36 volts and the 50v is around 59 volts. So if we were to use these voltages it could be a problem, so we would need to “regulate” the voltage for what we needed.
A solar panel, a storage device and a regulator is what you need to run a solar panel making DC run DC items that you have.
We built a small system from a solar panel to a DC to DC converter which would provide power to charge a battery from solar. the storage in this case was capacitors as there was a minimal load that the panel could meet in most circumstances.
Going Off Grid (energy)You can have a micro inverter, this converts the DC to AC and the amount of AC provided would go into the house hold electric that you would use. This would be up and down power unless you have a hybrid or an off grid system.
What’s the difference with off grid and hybrid or grid tied?
off grid does not work in parallel with the grid, so its detached and a stand alone system.
Can I use off grid in my home?
Yes you would have to attach a ATS which can connect and disconnect between the grid and off grid.
How many solar panels would I need for my home?
This is wrong to think this way about solar. solar works during the sunlight, you house runs day and night, so its not the solar panels but the power storage to run the home and the solar to keep that charged.
Can I run something that just runs during the day?
You can, but there can be some issues such as start up power requirements. this means that you would need to manage the power delivery which is not all that difficult, but to turn on when the power level is met, rather than on as the power grows. Power is voltage and amps. you will get voltage very easy from a solar panel, its the current which does the work.
When it comes to solar it is a feast and famine, winter time reduces the sun hours and the production of power by around 12 times. so you would need to consider the power you use to work out how many panels you would want, how you mount the solar panels and in which direction ( search this site for “tilt”)
If you have around 100W load then 800w of solar would supply power even on fairly dull days, but there will be times that this will drop. unless you have storage for the power that you can cover the drops. in general a basic load ( AC) in the house 2 panels will work. you will not meet that load for around 165 days of the year in winter, but you should be fine between March and October.
DC to DC converters means that you can run most things regardless of the voltage difference, however most professionals would use a higher system voltage as this results in a lower current. High currents require big cables and puts more stress on hardware. You should have a higher input voltages than the battery charge voltage. for example a 12v battery charges at 14.6volts. so you would need incoming power greater than 14.6volts.
This is not always true as you can boost up the voltage from a lower voltage supply, this will lower the current as it does so.
Could you charge a Scooter from a solar panel?
Yes, you would need to match the voltage and we sell devices that can charge the battery on a eScooter.
You do need to have protection added and its wise to have a small storage available.
How do I work out how many panels I need?
Panels have a STC rating and they will sell you this information, do look at NOCT data for a more real world performance dataset to work from.
Look at the power draw of what you want to run, by multiplying the volts and amps (current)
12v 2a would be 24 watts for example.
You would then need to multiply the time you want that to work.
If you have 24w running all day (24 hours) thats 576wh a day
so we now know we would want to make 576 watts for the day and we could store this in a battery.
we need to take our day load (24) and our charge requirement, we will say there are 14 night hours. (336wh)
We then take the night hours and divide this by the day hours, and then add the load so that we can run the device and charge the storage. thats 84wh over 4 hours and the load brings the total to 108 watts.
108watts would be the minimum power requirement over a four hour day. ( this is sun hours)
sun hours are when the sun powers the panels in relation to the array size and the planets tilt.
for example a 100W solar panel with 4 sun hours would make 400w over the day.
You can use the search function “sun hours” to find out more and the time charts
in the summer there are between 8 and 10 sun hours in the days, so that same array could make between 800w – 1kw per day. Winter is usually measured as 1 sun hour, so you would make 100 watts during the day. ( feast and famine)
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