Install A Solar Kit

Firstly why a solar kit? because they come with the solar panels, a charge controller and cabling to connect it and they are usually foolproof, in this piece it can be installed at home, on boats or motorhomes and anywhere where battery charging is needed such as off grid, now solar has moved on again it is becoming practical and affordable and the only thing you need to obtain is the battery to charge and basic DIY skills and tools.

Solar panels are now becoming cheaper and more efficient and this means they are within reach of many people for basic battery charging duties and if you get batteries charged you have 12 volts readily available which you can use as is, or connect an inverter and have mains 230 volts for a limited time depending upon your battery capacity and inverter sizes. Along the way there are many things people need to be aware of to prevent themselves being overcharged for inferior equipment or totally ripped off by unscrupulous companies of which there are plenty.

This piece is for a simple installation for basic battery charging in a simple system for home or DIY installation and assumes you have both suitable places to mount your panel/s and the basic skills to undertake their mountings and wiring and I would begin by buying a kit which has the cabling and charge controller included as all you will really need are the mountings which would be Rawplugs and screws for mounting onto masonry, or just screws for mounting on wood.

To begin you need a suitable roof or space to mount your panels and we begin with the internet as you can glean useful information from many sites by putting your postcode or address in and it finds your location, it then gives you the best direction to point your panels in and importantly, what angle to mount them at as this changes throughout the year as the sun is higher and lower in the sky throughout the year and ideally for maximum efficiency you need to have the three optimum mounting angles for different times of the year and the capability to quickly and easily change these angles as the sun changes. You further need to ensure there is nothing shading the site and normally this would be trees and high hedges but overhead lines such as telephone or power cables can also shade them and significantly reduce their efficiency. To explain this we need to understand that solar panels consist of cells connected in series and a number of these series connected cells are connected in parallel as series connected cells generally give us the voltage and parallel connected cells give us amperage or current. If we have a series of 20 cells and a bird does its business (which they always do) and it lands on cell 13 it blocks cell 13 from producing electricity and anything beyond it in that series, so cells 13 to 20 would not produce electricity where as cells 1 to 12 would produce electricity. This gives our next potential issue and that is cleaning them as roof mounted panels may be inaccessible to many people, so ensure you have accessibility to clean them periodically and on a shed or outbuilding roof a long brush may suffice, on the roof of your three storey home usually means paying someone to do them so a potential additional expense to your alleged free electricity.

Next are the solar panels themselves and these generally come in three types which are Monocrystalline, Polycrystalline, or Thin Film types, there are many other types but they tend to be for more specialised installations and not for the home user or for home use. Of these three types these are divided again as both the Monocrystalline and Polycrystalline are the most popular as Monocrystalline are the most efficient and Polycrystalline are less efficient but cheaper and both have a lifespan of 25 years + and both are slightly affected by temperature where as the even cheaper and even less efficient Thin Film panels are much less affected by temperature, but much less efficient to begin with. Many advertisers quote tracks or routes and these used to be 5 routes or tracks and this refers to the way the solar cells are connected together and if that pesky pigeon plops on solar cell 13 and blocks it you may find a panel with 9 connections or routes and this is additional ways the electricity has to travel so you only lose solar cell 13 and cells 14-20 still produce electricity and is sent along a different route so you don’t lose it and your panel is still efficient.

Efficiency is another element we consider as every solar panel has a life span and during the course of this lifespan they become less efficient and this is usually listed as loss of efficiency over a specific time and generally most solar panel manufacturers list their efficiency at 20 years old and a panel with an efficiency of 95% at 20 years is better than one with an efficiency of 90% at 20 years. These efficiency figures are directly used to compare solar panels, particularly on price as the extra efficiency may not be worth the extra cost and only you can decide.

All solar panels operate at a maximum voltage and generally this is a maximum of 18-22 volts and this is crucial to know as this can decide how many solar panels you have and how you wire them as wiring them in series will increase the voltage while wiring them in parallel will increase their current and this is critical information as your charge controller may have a maximum voltage and a maximum current input and if this is 40 volts you cannot wire solar panels in series as two at 22 volts maximum would equal 44 volts and exceed the charge controllers capability and fry it. This is where people need to study all the elements of the kit and ensure they match and if they build their own system this component matching becomes more critical as many may want to increase their charging capacity by adding more solar panels and they need to know their charge controller will handle it, so basically futureproofing.
One final element to consider is the structural strength of your proposed mounting place as the UK has variable weather conditions and a solar panel covered with snow is heavy and several solar panels covered in snow may exceed the weight your roof may carry and collapse it, so check and err on the side of caution.


Solar panels connect to something called a charge controller and this takes the high voltages of a solar panel and convert it into a charging current as the panel may provide around 22 volts to the charge controller and this needs to keep it at something called a “float charge” as this is the ideal voltage for the battery to charge and connecting 22 volts to it will make the electrolyte gas and boil it to evaporation and your battery is dead and useless. Batteries charge on something called a “charging curve” and basically this means as the battery charges it accepts more charging current and charges quicker and many people will see a charging battery takes a small amount of charging current which increases as the battery charges.

Batteries in this article are the standard lead acid batteries for the purpose of this article as many people can afford a couple of decent batteries for their system but cannot justify the expense of hundreds of pounds for a lithium battery for a simple system. When batteries charge their state of charge is determined by cell voltage and remember a 12 volt battery has 6 cells and when an individual cell is specified as measurements you have to multiply this by 6 for a 12 volt battery. Before we go further into charge controllers we need to understand batteries and specifically charging and discharging as this is a chemical process and both cause gases to be discharged, in addition both lead acid and lithium batteries are so similar they can be deemed the same.

When a battery charges it goes through stages and each stage serves a function, I have a digital battery charger at home and this has seven stages but not all of them are used, in addition there are two main types of charge controllers and they only need three stages.

Stage 1 is called Bulk Stage charging and this charges around 80% of the battery and does this by something called constant current where a constant amperage is applied to the charging battery until it is around 80% charged.

Stage 2 is called the Absorption Stage and this is the remaining charging stage of the last 20% of the battery and it does this by charging at something called charging at the absorption voltage of 14.1 – 14.8 volts and it decreases the charging current at the same time.

Stage 3 is called the Float Charge and sometimes called the topping off charge and this reduces the voltage to 13 – 13.8 volts and the current to less than 1% of the battery capacity and this maintains the charged battery at full charge until it is needed. For a 100 amp capacity battery this means the battery will be float charging at 13 – 13.8 volts and at less than 1 amp.

Charge controllers come in two main types for these type of home set up’s and they are called PWM or pulse width modulation and MPPT or maximum power point tracking and either will suffice for charging and maintaining a battery for home use.
PWM or pulse width modulation became popular in battery charging circles in the 1990’s and was the go to battery charging technology for many things and the modern electronics of the day allowed better battery tracking and this essentially fine tuned the charger to give the battery a better charge. It did this by supplying a series of pulses and a feedback circuit measured several parameters which dictated the length and duration of these pulses and it was effective for its time.
MPPT or maximum power point tracking is a more advanced PWM system and this is because of advancements in electronics technology and their ability to track the battery charging anywhere on their charging curve and alter both the charging current and voltage to suit the precise location on the charging curve and provide the optimum voltage and current. This has another advantage over PWM in that it can take surplus voltage and alter this into charging current through inversion technologies and this makes them around 30% more efficient than a PWM controller and they can often exceed 40% more efficiency when PWN controllers dump surplus power.
Think about this for a minute as a solar panel may supply 22 volts and we need 13-14.8 volts to charge our battery, depending upon the state of the charging battery and if this is bulk charging and drawing the full 14.8 volts and the panel supplies 22 volts we have a surplus of 7.2 volts and the PWM controller will dump it while the MPPT controller will change it into charging current. Basically it is use it or lose it with an MPPT controller while the PWM controller it will lose it.


Connecting everything together means wiring and modern systems employ the cheapest and easiest to produce and the most popular connectors are called MC3, MC4, PV, or Tyco and of these the MC4 has emerged as the most popular as it is a single connector meaning it only connects one cable, they come as both male and female connectors so they literally plug and that’s it. Most solar panels come with a male and female MC4 connector and you simply plug your connector cables into them and the standard wiring system means you cannot get it wrong so it is basically a plug and play system. Many kits which supply the cables often supply shorter cables and it is crucial to ensure your chosen location to mount your charge controller is within range of your cables, or you buy longer cables, and your battery is located within range of your charge controller.

Installing your system is simple but there are some simple tips and specific ways certain things should be done as once a solar panel is mounted it is producing power and this power needs to go somewhere and we begin with the solar panel and ensure it is not flat down to the roof as they need airspace underneath them to provide cooling air. Most manufacturers recommend or specify 2” or 50mm depending where you are in the world, so ensure you have this space for cooling air to get under your solar panel. Next is the location of your controller and ideally this needs to be out of direct contact with the rain and snow to prevent the risk if water ingress during a thunder storm. Many people purchase an electrical box and use the knock outs to put cable glands in or simply buy a cheap plastic transparent sandwich box and drill it and mount the controller inside it and this keeps water off it.

We have briefly touched on batteries as these are the final part of our system and it is crucial to obtain the correct sized batteries as too large means they struggle to charge up in periods of low solar panel output and too small means they will fail to give sufficient long term power to your application, particularly during a prolonged power outage. This situation is exacerbated especially when an inverter is used to power your fridge/freezer to keep your food frozen and you have just filled it from your garden or supermarkets of freezer specialists to see you through several months.
In all cases the best batteries are those with the highest cycles or cyclic rate and the cycles or cyclic rates are the number of charge and discharge rates they have and manufacturers supply these figures; and by shopping around and studying the specifications you can often weed out those batteries charging a premium just for their name. Remember, if a battery manufacturer states the number of cycles they ae designed for then this is the minimum number of cycles it must meet and in reality you need to remember this is the minimum number and most batteries regularly exceed this so let’s look at different batteries.

Car Batteries are often the cheapest and they are designed for a fairly hard life as they have an amp hour rating and something called a cold cranking rating or CCA and the CCA rating is the number of amps it will provide to the car starter motor to start the engine under all conditions ranging from below freezing to a scorching hot summer. They act as a reservoir until the engine is running and fill in any charging issues such as winter when everything electrical is running and the alternator output cannot meet demand and the battery will fill in this shortage. Cold cranking really hurts batteries, especially in winter when the cold oil is more like sludge and adds more friction to the cranking engine, then the vehicle has its lights, heaters, demisters, rear screen heater, heated seats, and everything else switched on and it spends a lot of time idling in city traffic jams and using battery power until things are switched off and demand drops below what the alternator can supply, it can then begin charging the battery.

Leisure Batteries are designed as something called “power station batteries” as their sole function is to act as “house batteries” in caravans or motorhomes and on boats to provide the power for each application and unlike a starter battery they do not have the huge discharges associated with engine cranking which are effectively short circuits. Due to this they are constructed slightly differently and use heavier duty construction so large discharges affect them less that a car starter battery.

Deep Cycle batteries are often called “traction batteries and they are the heaviest batteries of them all and are tough, they can withstand huge discharges without issues and be nearly discharged to flat and then recharged multiple times and are the preserve of electric traction and were used in equipment such as the electric milk floats.

Buying batteries is not straightforward and you need to check specification and price and always buy the best battery you can afford and base this upon specifications and NOT brand image as with the top brands you are often paying for their name and nothing more. If possible always go for the heaviest battery with the most duty cycles you can afford and if possible go for the traction batteries. Many people will go solely for car batteries based upon price alone and those more affluent but not rich will opt for the leisure batteries and their better durability and this can sometimes be a mistake. Locally I checked out battery prices from a local specialist supplier and found a leisure battery rated at 110 AH for £134.50 with a 5 year warranty and a car battery rated at 105 AH with a 2 year warranty for £155.00 so you really need to research and be prudent.

When you install your system you mount your solar panels and ensure they are accessible so you can alter their angle throughout the year and they need to be monocrystalline and you mount your charge controller in a suitable location and get an MPPT controller if possible and then mount your battery. Connect your battery to the charge controller first and never connect your solar panels first and when you connect your battery the controller usually gives a visual alert, when you get this alert you connect your solar panel wiring and you often get a second visual alert and you are charging. Always ensure your battery is accessible and follow some simple basics, ensure you connect to your battery with suitable connectors and the connections are solid and secure and coat them with a thin coating of petroleum jelly.

Sit back and watch your battery charge and drop to a float charge and be ready for action.

Some basic questions?

Can I connect more than one battery? actually yes and if you connect them in parallel cou get the same 12 volts output and the total amperage output of all the batteries, simply, if you have three 12 volt 100 A/H batteries connected in parallel you will get 12 volts but 300 amp hours.

Can I put different amp hour rated batteries in parallel? in theory yes, but in practice no because they only have one charger they need to be the same size and equally charged before connecting them as one battery may (will) discharge the others and not shhare the charging current equally.

Can I fit an inverter to my battery bank? yes and always hard wire it directly to your battery abd avoid things such as crocidile clips as they give poor connections and are insecure.

Can I wire a 12 volt circuit directly to my battery? yes and again a hard wired 12 volt circuit is ideal for emergencies as it is foxed in the home and you can use 12 volt items directly from the caravan/motorhome wiring industries.

I have been using solar for the past year to power a 300 ltr chest freezer
in a outhouse 4x 100 watt panels 4x 90 amp hour leisure batteries & a 3000
pure sine wave inverter.plus controller and fittings.
Despite the only place i could fit the panels was far from ideal it works pretty
well ,although i turn off the freezer about 3 hours before sunset & 3 hours after
dawn the freezer remains well below freezing.

The only thing i would add is dont buy cheap cr*p especially the inverter.

As Daveiron beat me to it, do not buy rubbish and do your research and aim for mid range at least.

A note of battery research:

It is prudent you do this and take the time to do it correctly as you will often find some lesser well known names offer quality products as their sub prime or budget ranges and batteries are no exception and sites such as Amazon are an example of these budget brands and a place you can compare proces and specifications.

If you research correctly you may be pleasantly surprised that a budget brand called Powercell is the sub brand of a company called Panasonic and Panasonic make some of the worlds best batteries and own several brnds, which are not all the same and are not made in the same factory as many people suggest. Powercell are made in a Panasonic factory in Belgium and they don't omit several things other battery manufacturers do to cheapen them and this is shown in the fact that other budget brands only have a 1 year warranty and Powercell have a 4 year warranty which is a clear giveaway.

Yuesa are another prime brand and began with smaller batteries and built them very well and at one time not too long ago and they were the go to brand for manufacturers o0f portable power items such as medical equipment, critical application systems such as emergency exit signage in critical buildings and the go to choice for dedicated high security systems and many more applications. Yuesa turned to small batteries for motorcycles, portable generators and even the ride on garden mower where they would be stood for months through winter and expected to start first time. This expanded to other batteries such as car and leisure batteries and the price of the batteries put people off them in favour of cheaper batteries.
Yuesa now have their own sub brand and this is called Yucel and this brand is actually a sub brand while it uses little dirrerent to the Yuesa brand, basically their housings are made from cheaper and thinner materials so they wont take the abuse a Yuesa battery will take and there are very tine changes in chemical composition, buy they are at least 25% cheaper; I have actually tested them in side by side tests and I actually prefer the Yucel.

Do you have links to any suggested products? Particularly the charge controllers. It seems to be a bit of a minefield at the lower end, with choice between PWM multi stage chargers like ..
https://www.sunstore.co.uk/product/ep-solar-5a-charge-controller-with-usb-output/

Or others stating MPPT but not explicitly describing the charging method.

I have a couple of solar panels which I've used for battery charging during power cuts, but without a controller/regulator they can't be left unattended.

I have Renogy panels & charge controller

https://www.ebay.co.uk/itm/124898733875?hash=item1d148b6f33:g:~x8AAOSwRJNjkX0E&amdata=enc%3AAQAIAAAA8AENhr1I7wDKp06hoiOQwppYNH6iiQ2BdJOK9el0dZ9A4djjDrQZZfgYFfqOicpYO8iYE8ijQv7xwqDKxlkZOe02ET9F87zqqxfcobWzrLjCCkYZ4r8TowsehDIpq7DBFEf2rXz7cdbGPTQx1t2IqQyROH3VOltfiobmb%2BDVFMJTX6fAH28J4imZsWb%2FFt%2F5mzQ8VrGzyss%2FsKECrdZGwWevVMVd8EqkMpmZ4PXMFPJCPjYJ7dUmXHq5FyBBZgWES2yLPs%2FR68Kvoc%2FFaqUCl%2FuBhbwH3ylvY95pD8ShDdZjCEHfuVm7qk7p%2FvmB%2BnW4SQ%3D%3D%7Ctkp%3ABFBM5qKK9tZi

daveiron wrote:I have Renogy panels & charge controller

Thanks, I remember you writing about your setup but I don't think you mentioned brands.

flyingfish wrote:Do you have links to any suggested products? Particularly the charge controllers. It seems to be a bit of a minefield at the lower end, with choice between PWM multi stage chargers like ..
https://www.sunstore.co.uk/product/ep-solar-5a-charge-controller-with-usb-output/

Or others stating MPPT but not explicitly describing the charging method.

I have a couple of solar panels which I've used for battery charging during power cuts, but without a controller/regulator they can't be left unattended.

Currently a company called JA Solar Jam manufacture a solar panel called the 72S30 which blows everything else out of the water as they are a 550 watt panel costing £282 each and as far as charge controllers go it is a case of matching them to your panels and ideally leaving a little scope for attaching more panels if you require, then looking at the reviews of the products by experts as an MPPT controller is automatically 30-40 more efficient than pulse wave as it uses newer technology and doesn't dump power.

If its any use,this is the spec on my inverter, Whilst there is no price difference
between 'modified sine wave' & 'pure sign wave ' i bought pure sign wave for
the reasons listed.

Advantages of Pure Sine Wave Inverter

1. Output voltage wave form is pure sine wave with low harmonic distortion and clean power.
2. Inductive loads like fridge, freezer and motors run faster, quieter and cooler.
3. Reduces audible and electrical noise in fans, fluorescent lights, audio amplifiers, TV, Game consoles, Fax, and answering machines.
4. Prevents crashes in computers, weird print out, and glitches and noise in monitors.
5. Reliably powers the appliances that will normally not work with modified sine wave inverters.

SPECIFICATION

Output Wave Form Pure Sine Wave
Input Voltage DC12V
Rated Power 1500W
Peak Power 3000W
Maximum Power Efficiency 85%
Capable of running maximum resistive loads 1300W
Capable of running maximum inductive loads 400W
No-load Current <0.8A
Output Voltage AC220-240V
Output Frequency 50Hz±2Hz
Internal Fuses 4x40A
Soft Start Technology YES
Cooling System FAN
Overload, Overheat Protection YES
Overvoltage, Undervoltage Protection YES
Output Short Circuit Protection YES
Weight 3KG
Dimension 280x188x95(mm)

assassin wrote:Currently a company called JA Solar Jam manufacture a solar panel called the 72S30 which blows everything else out of the water as they are a 550 watt panel costing £282 each

Available here for £140 which is pretty impressive in terms of W per £.
https://www.usolarshop.co.uk/attribute/supplier-part-no/jam72s30-545-mr/

daveiron wrote:If its any use,this is the spec on my inverter, Whilst there is no price difference
between 'modified sine wave' & 'pure sign wave ' i bought pure sign wave for
the reasons listed.

Cheers, yes an inverter is part of my plan as well, specifically to run the freezer during power cuts. The new freezer is very low power but that means it needs to run quite a few hours every day, longer thsn I'd run a generator.

flyingfish wrote:

daveiron wrote:If its any use,this is the spec on my inverter, Whilst there is no price difference
between 'modified sine wave' & 'pure sign wave ' i bought pure sign wave for
the reasons listed.  

Cheers, yes an inverter is part of my plan as well, specifically to run the freezer during power cuts. The new freezer is very low power but that means it needs to run quite a few hours every day, longer thsn I'd run a generator.

Save battery power and in the event of a power cut you set your freezer to its coldest setting, do not open the door, run your invertor power until the freezer stops cooling which is rarely more than a couple of minutes and switch the invertor off to save your battery, leave for 3-4 hours and switch your invertor back on and let it cool again and you can run your freezer for several days without recharging your battery.