Perhaps it's your first day reading about renewable energy, or your on the lookout for some information for your installation ,we would love to help !
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Solar panels are an exceptionally clever piece of kit. They take sunlight (a free resource) and turn it into energy. The technical name is (photovoltaic) ,which is the process of turning light energy into electrical energy, through the use of semi conducting materials (it's going to save the planet).
Mono or Poly (what !)
Mono crystalline solar panels are slightly more expensive than Poly crystalline panels, for that you'll get a higher efficiency rate (often +5%), they will last longer, and are less sensitive to temperature changes. If you can afford it, always go Mono ! You'll spot them a mile off, as Mono adorn a black colour, where as its cheaper rival has a distinct blue colour.
If your really into the jargon (Monocrystalline solar cells are cut from a single, pure crystal of silicon. Whereas polycrystalline cells are composed of fragments of silicon crystals.
Wiring in Parallel = Same Voltage with higher current
The most common solar panels will give a regulated 17v of electricity per panel. If you are opting for a simple 12v setup, you can wire (if using more than 1 panel) in parallel. Wiring in parallel increase the (amps) or power that your panels can generate whilst keeping the voltage constant. This is achieved by connecting all the +'s and all the -'s together. You will need to ensure whatever charger you are using can handle the amount of power (in amps) you are sending to it. This setup will be most cost effective, as it will allow you to use a PWM solar charge controller, which we will cover in more detail below.
Wiring in Series = Higher Voltage with same current
Resistance is the opposing force, when sending current or (power) through a cable. The higher the voltage the lower the resistance. In long lengths of cable. Resistance can be problematic, so its generally advised to wire multiple panels in series (if you can), which means connecting + to - in a string. You will take the + from one panel and connect it to the - of the next panel.
In doing this, your power stays constant but your voltage is multiplied.
If you had 3 panels in series, you would have 3 x 13-18v, around 55v, and a constant power of around 3-4amps in good weather. We will cover this in due course, however an MPPT charge controller, can accept a varying voltage and convert back down to 12v for you ready to charge your batteries. One of the downsides of a series setup is that if one of the panels develops a fault, the rest of the system goes down. In larger scale setups, you will generally have multiple banks of series panels, according to the voltage of setup required.
Now we've covered the basics, let's talk about the choices of panels available.
Rigid panels (Framed in Metal)
Come in a range of shapes and sizes and physical makeup. The most cost effective panels are set into a light weight aluminium or steel frame to give the panel its rigid strength. These metal surrounds can then be used to fix the panels down to a roof using a Z bracket or alternative fixing. When opting for a rigid panel, you can use a bracket to fix directly to the panel, and often the panels will come with pre-drilled holes so you can connect your bracket with ease.
Flexible panels (Set into Plastic, yes that horrid stuff that never disappears even in the ground)
These panels are generally suited to the 'transport' market, i.e fixing to cars/boats/vans etc, as they are bendy so can go around certain shapes and generally take up less space and can be lighter.
There are no real disadvantages to these panels when compared to the rigid, other than the increased risk of damage as the support structure for the PV cells is reduced. A flexible panel is fixed either through suction cups, or a silicone adhesive. Flexible panels generally come with 6 holes around the perimeter, so they can be strung up or fixed with cables ties to virtually any surface. Just be sure to secure your panel down well, so it doesn't blow away in adverse weather. Most flexible panels have a limit of 25 degrees of curvature.
Shade or cloudy days :(
The enemy, locating panels in good sunlight is critical. Use this handy tool to find out where the sun rises and sets in your location. The angle and orientation of a panel are important, using a flexible bracket, you can test and adjust your panel over time to ensure you gain the optimal sunlight throughout the day.
Life Span & Maintainence
PV panels should be cleaned regularly, with a basic non corrosive solutions, which will remove the dust and any other impurities that may land on the panels. Cabling should be inspected annually for any signs of pest damage or wear. Panels will generally last up to 20 years depending on the manufacturer.
The solar charge controller takes the energy from the solar panel, and places it gently into the battery ready for you to use. When purchasing a charge controller there are many things to consider, but we will start with a few of the most important.
MPPT - Maximum Power Point Tracking
If you can afford it, its worth going for one of these. This type of charge controller will draw the maximum voltage from the solar panel (reference back to the learnings above) less resistance = more power, so you'll be able to wire your panels in series even if only powering a simple low voltage 12v battery setup to get the most out of your setup.
When purchasing one of these controllers
- Ensure the VOC which is the open circuit voltage (add all your panels together) is below the rating of the controller.
- Ensure the current you are going to be harvesting from your panels is below the rating on the device.
PWM - Pulse Width Modulation
This more basic type of charge controller, will draw current out of the solar panel at a voltage just above that of the battery, therefore in some instances limiting the voltage off your setup. When selecting a panel for a PWM charger, you want to find a panel thats voltage is sufficiently above that required to charge the battery in your setup.
Victron energy controllers
We love these guys, so local to us, just a stones throw from the UK, although all the kit is made out in Malaysia, so its had quite a journey to get here. Blue power is their phrase, perhaps that's because holland has so many canals, we will never know. You can be sure when buying Victron, its been designed to last, heck they’ve been in business for over 25 years and still going strong.
Smart Charge Controllers
If you’d like to get fancy, we sell smart controllers that you can sit and oogle at from your phone, but it won’t help get more out of the sun, in-fact it will just use more of that valuable energy that you’d rather be using to watch your favourite film. Sorry Victron ! With these controllers, you'll be able to see how much current is flowing into your battery, and customise your charge controller to the type of battery you are using. If you've got the budget, opt for a smart bluetooth enabled smart controller, which you can access from your phone or tablet.
Well, you’ll need one of these to store all that amazing energy you are capturing from the sun ready to use in whichever way you please.
wooahh…. way more expensive than their counterparts, smaller, lighter, can accept energy from the sun faster, and let you use pretty much all of their storage capacity. If you’ve got the money, go for it, but its really not that important when you are just starting out.
Well you can probably just take one out of an old car, than buy it from us… although don’t blame me when the car doesn’t start in the morning, that is unless you drive an electric car, and you won’t find one under the bonnet. Lead batteries need keeping an eye on, topping up with water occasionally, and don’t really like being used all that much, in technical lingo thats depth of discharge. Generally heavier than lithium, but much better on the wallet.
A good compromise in our view. Much kinder on the purse than lithium, but better performing than lead. They don’t like being drained down all the way, so you’ll have to keep an eye on that if you want your battery to last you for many years to come, but a great battery to start out with.
Which size of battery is right for me and how do i work this out ?
It's often best to start with calculating your power requirements. On the back of most devices you will find the current in amps and the voltage. Voltage x amps = watts, a measure of power consumption. So for example, if you wanted to power your computer at home, for 8 hours a day, you'd need to calculate the power consumption. Most energy providers charge by kwh which is a measure of 1000 watts of energy.
Computer Consumption with screen = 5amps
Voltage = 13v
Watts = 65, so in an 8 hour day you'd be using 520 watts.
Now lets work backwards, we know that our setup is running on 12v, so we'd take our watts / voltage to get our power requirement
520 watt /12 volts = 43amps.
Our starting point on the search for a battery is therefore one that can at the very least deliver 50amh of power at the voltage I require.
What's important to remember here is depth of dis-charge. If you are buying a lead battery you'd need to be going for 100amh + since the depth of discharge is around 50%. With lithium a 50amh battery would suffice. You'll also need to factor in days, when the energy harvesting from the sun is low, so you might want to store excess energy on days where you won't be using the batteries for powering your device.
And finally, you'll need to consider how much power your solar setup can deliver. There is little sense having a large battery, that will never be filled, as your panels don't have the power to fill the battery.
Battery Protect Systems
Well with any battery, they don’t like being emptied completely, its a-bit like being dehydrated they always like a’bit of charge to keep voltage up. This protect device makes sure your system turns off when its reached a point that its not comfortable with. If you can afford one, it will ensure you pro long the life of the battery. They are super simple to add into any setup and the fancier one’s give you lots of nice information about how your battery is doing over bluetooth.
Battery Management System
In more advanced setups, you may want to introduce one of these. This device will give you lots of information about your battery, turn it off when the voltage drops below a safe point, through the on-board relay, and also inform you of how much current or power you are using, which, with the right setup, will inform you how long your batteries will last until depleted in hours and minutes, handy if your watching your favourite film. You'll set this up by passing all negative loads through the shunt, which is included with the product. Expect to pay around £100 for one of these, depending on your setup and current load.
Here’s the clever bit, an Inverter takes the energy you got from the sun, out of the battery and into a useable format, for your everyday appliance.
Which inverter is right for me ?
You’ll need to buy the right inverter based on how much energy you think you’ll be using and what battery setup you are running, often this will be 12 or 24v.
An average laptop and desktop screen uses about 70watts of power. Always go for an inverter with slightly more power than you need to ensure its never straining itself too much as this will reduce its lifespan, and potentially be a safety risk.
Go for what you can afford here, as the larger inverters will give you better longevity as you add more batteries and panels in the future, you’ll be able to power more things, rather than have to re-invest into a new inverter.
A great start is a Bestek Inverter, Bestek are one of the best, and whilst they do come from China with a few delivery miles, these guys know a thing or two about inverters, and they come at a price that is gentle on the wallet.
When purchasing an inverter, always check its got the right output connection (if you are going to be plugging something directly in.
Large scale inverters
When considering a large scale home setup, you'll come across inverters with built in battery chargers, or inverters with on/off grid capabilities, that allow you to feed power back into the grid, or allow you to switch between grid and battery power. You'll most certainly need an electrician to set this up for you safely, and not attempt to wire this up yourself unless qualified to do so.
Compact All-in-1 Systems that are plug & play out of the box
Our super smart range of all in 1’s are the perfect step for beginners into solar/renewable power. No hassle, no fuss, plug your panel into the system, and away you go. You’ll not be able to change the battery capacity or inverter power in the future with one of these, but you could always pass it down to the next deserving soul, and get yourself a’bit more kit to play with now you’ve become a solar pro.
Pro's & Con's
- The all in 1 systems allow you the opportunity of having a portable power station that can be charged by the sun or grid (but always opt for the sun).
- On the entry level models you will only be able to have 1 or 2 100w panels to charge the device, which means your charging current is likely to be capped at around 8-10amps.
- The portability is an amazing feature, which means you take it around your house, to power the item you are using, and then return to charge the battery at your panel setup once your done. Of course you can continue to use the device whilst charging as well.
- They are plug and play, the come with additional USB and C ports, as well as standard 12v power outlets.
- Some of the smarter systems come with LED screens which will inform you how much power you've got left, much like the battery management systems we covered above.
- The only real con I can find is the inability to upgrade in the future. If you start to use more power or find the battery life prohibitive, it will be a case of buying a new system.
These devices are a GREAT way to introduce someone into solar energy, and kick start their more sustainable future.