If you are planning a DIY solar install and don’t have experience you might want to read this first and avoid the ten most common mistakes that others have made:)
For now, in no particular order:
Mistake 1: Voltage drop and the length of cables
For most people they select the core voltage of their planned solar system as being 12 or 24v because that’s which voltage their batteries / battery banks or solar panels run at. However there is at least one other aspect( probably many more ) that need taking into account.
When you transmit power through cables it is degraded slightly, this can be calculated to a formula and is known in electrical worlds as voltage drop.
Best practice is to place the charge controller, batteries , inverter and panels as near to each other as possible in your design.
If you transmit the low energy DC voltage from your panels and batteries it can degraded by as much as 10 or 20 % over an extended length of 5 or 10 meters. You will also need to calculate the correct thickness of cable to transmit that power with only a small loss, the larger the cable the less loss.
If you transmit at mains standards 220-240v AC here in europe then there is a wider acceptable range of loss that will be more efficient over longer distances.
For accurate examples and formulas to work out voltage drop , see these electrical links:
Mistake 2: Still got energy inefficient devices running !
The energy you produce needs conserving and using efficiently. If you spend100’s dollars on solar panels, charge controllers and batteries and then use it to power your tumble drier on a sunny day its a clear waste ! however , thats about what you are doing if you are using a traditionally power rated product.Always look for an energy efficient device that is specially suited to low power.
Low power appliances of all shapes and sizes are available, including computers, fridges, televisions, lights, water heaters, cookers and more.Investing in lower power appliances will save you money in the long run and reduce the size and complexity of your solar generating needs.
Mistake 3 – Over or Under-sizing the setup
Estimates are just that, when you start using your solar power, you will start to realise your true energy usage.
Solar systems are intended to be modular, in my opinion its better to start smaller and learn the lessons and get experience with the kit.
If you do end up damaging something it will be less costly. You might you will run smaller split systems, like a small set of panels for outdoor lighting or water pumping to use an older first setup and use a new set of panels to power your home.
A solar system could cost you allot of money , 10’s of thousands of euros or dollars. You can get a small setup for a laptop or so for a few 100 dollars, it might be worth starting small and making sure your comfortable before commiting1000’s !
Mistake 4 – Not building safety into the design
Solar energy not only has benefits, but it also comes with dangers ! Solar panels used to generate electricity can do so effectively, an 80w panel getting sun for a 12 hr day is generating almost a 1kw of electricity. Lets not forget that electricity itself can kill. Consider getting some practice and knowledge with electric wiring and connections before attempting to work on solar panels and do not forgot to look at fuses, charge controllers and other fail safes !
Mistake 5 – Panels not in the sun !
There is a balance in all things, some people would rather not see there solar panels, i personally like to, but don’t place your panels in a location that isn’t sunny all day. You should site your panels in a spot the gets optimum sun all day long, try to avoid places where trees and other obstructions create shadows and try to elevate the panels slighty to avoid any ground shadow at certain times.
Tracking the sun ? There are various ways to achieve this, it can be as simple as mounted your solar array onto a hub or disc that can be locked into afew positions or turned during the day ( think safety here, solar panels swinging in the wind is no good ! ).
Commercial solar trackers are also available. Having used one i can vouch that you catch more sunlight with them, the docs say you get upto a 50% increase in solar yield using an automated tracker, i cant verify the numbers, but it definitely increases the amount and time of solar power you can receive . Start off small with a panel or two and grow into a tracker if needed is my advice.
Mistake 6 – Using mirrors and other reflective devices without considering cooling
Its little known and even further misunderstood, but if you use a mirror or other reflective device you can increase the output from a solar panel.
If you think about it , it makes sense more solar energy directed at the panels will increase the energy output, but consider the heat created by the mirror or reflector you are directing at the panel.
Solar panels become more in-efficient as the panel temperature increases, so if its a hot day you might actually but hurting the output by doing this !
Research the subject , you might need to make some sort of cooling provision or other arrangement to get rid of the extra heat, make sure you are spending the extra effort wisely. Off course if you are in a low sun season mirrors and reflectors might be just the solution to your problems.
Give it a go an let us know !
Mistake 7 – Ventilation for batteries ! Explosion alert !
The most commonly used batteries in a solar setup are the deep cycle lead acid type, these batteries are filled with acid solution and when charged may release a small amount of explosive gases. Its important you allow for this in your design.
If you store you batteries inside be sure to consider adequate ventilation and observe the standard lead acid battery safety rules,including washing your hands after handling and do not smoke near them , the gases given off are explosive !
Mistake 8 – Ordering panels from overseas
Solar panels are not exactly so delicate, but neither is trucking, shipping or postal workers. Solar panels weigh allot and are not easily handled, this adds to the cost of shipping and delivery.
You might be able to lessen or avoid these costs completely by doing deeper research and negotiation with a local reseller. Do a price difference and see how much the shipping and insurance costs are , you may be surprised to see that for less or even a comparable price you can source the materials locally and be able to discuss your needs with a more local contact.
Mistake 9 – The wrong type or size of batteries
Having made this mistake myself, really knowing the outcome but being impatient my first solar setup used standard car batteries. Now i must point out that if you use your solar setup in frequently this might work out ok for you, but for me and my 10 hour a day internet habit it didn’t work.
Car batteries are designed to give short high energy bursts for starting,they are not really design to slowly release energy over a long period of time.Also a car battery by design becoming weaker each time it is deeply discharged,in normal use it should probably be at least 90 % charged when used for car starting. Using a bank of car batteries i saw that extend use of a car battery really decreased its charge life.
So its important to have the right amount of the right type of batteries.Deep cycle batteries are designed for deeper discharge but you still do not want to discharge them completely. Making sure you obey these battery laws will also increase the lifetime of the battery which can be 10-15 years +
Most solar setups include a charge controller, which will normally stop drawing power from the batteries when they are lower than 30-40% charge in order to extend the battery life