Solar panels and battery back-up systems are a longterm investment, so it’s a choice you don’t want to make on the fly. Having a broader knowledge of the systems, options and workings of all the parts can save you a lot of money and help you make the best possible decision for yourself.
Which Solar Panel Type is Best?
There are a plethora of variables to be considered when you are buying a solar photovoltaic (PV) System. In this article we will take a look at the different types of solar panels on the market, the advantages and disadvantages of each, and then a few scenarios where certain types would be better ten others. There are currently three solar panels for home use on the market:
- Monocrystalline;
- Polycrystalline; and
- Thin-Film Amorphous.
Almost 90% of the world’s photovoltaics today are based on some sort of silicon. The silicon used takes on many forms, however the main difference lies in the purity of the silicon. The more accurately aligned the silicon molecules are, the better the solar cell will be at converting solar energy (sunlight) into electricity resulting in better efficiency of the solar panel. When deciding on your which solar panel to use, efficiency however should not be your main concern – cost and space efficiency are the determining factors for most.
1. Monocrystalline Silicon Solar Panel:
Monocrystalline panels are the oldest of our panel technologies and are created form a single continuous crystal structure. Since the cell is created using a single crystal (mono), the electrons have more space to move to create electricity. You can recognise this type of panel by its uniform and smooth appearance and black colour.
| Advantages | Disadvantages |
| Monocrystalline panels have the highest efficiency rate | Monocrystalline panels are the most expensive out of the panel types |
| These panels are made out of the highest grade-silicon | During the manufacturing process there is a lot of wasted material due to the way the silicone is cut |
| They are space efficient as they require the least amount of space compared to other types of panels | If solar panel is partly covered with shade, the entire circuit can break |
| They tend to perform better than polycrystalline panels at low-light conditions | These panels tend to be more efficient in warm weather |
| They have the longest lifespan |
2. Polycrystalline Silicon Solar Panel:
Polycrystalline panels are a newer technology and they are made up of multiple cells. They can be differentiated from monocrystalline panels as they are not as uniform in look, but rather grainy and blue, since they are made by melting multiple fragments of silicone together. Unlike monocrystalline-based panels, the raw silicon is melted and poured into a square mould, cooled and cut into perfect square wafers resulting in almost no waste of the original silicon.
| Advantages | Disadvantages |
| The production process of polycrystalline is simpler and cost less | Because of the multiple (poly) cells in each panel, the electrons have less space to move, thus lessened productivity. |
| High temperatures have less negative effects on efficiency compared to monocrystalline panels | They have lower output rates making them less space efficient. As a result, more roof space is needed |
| They are the Greener option since the wastage during the production process is less. | These panels have a slightly lower heat tolerance than monocrystalline panels, however the effect is so minor most residential owners need not even take it into account |
3. Thin Film Amorphous Solar Panel:
Thin film amorphous technology is a second-generation solar cell and more improvements are sure to be made over the next decade. These thin-film solar cells are manufactured by depositing one of several thin layers of photovoltaic material onto a substrate.
| Advantages | Disadvantages |
| Mass production is simple and as a result more cost effective | Not very useful for residential properties as they require significantly more space than other panels. |
| They are more aesthetically pleasing due to their homogenous appearance | Low space-efficiency results in increase of support structures and cables (PV-equipment) |
| They can be made flexible, opening up the possibility of potential new applications | They degrade faster than monocrystalline and polycrystalline panels |
| High temperatures and shading have less impact of the panel performance | They are less efficient than monocrystalline and polycrystalline panels |
4. Best Solar Panel for Home Use:
Since thin film amorphous panels are generally not considered for home use and take up an inordinate amount of space, crystalline-based solar panels are the best options (and they would most likely be the best choice even if you had the additional space). The differences between these panel types are minimal, and the choice will strongly depend on your specific situation. Even though polycrystalline panels tend to be less space-efficient and monocrystalline tend to produce more power, it is not always the case. Without a thorough site assessment in which the particular situation is examined it would be close to impossible to recommend one or the other.
Which Battery Type is Best?
Solar batteries are an essential component to your solar power system at your home. It stores all excess energy generated by our solar panels which can then be used when there little or no sun. Batteries used in home energy storage are generally made with one of these chemical composition:
- Lead Acid
- Lithium Ion
- Flow
- Nickel Based
1. Lead Acid Batteries
Until recently, the only practical battery technology used for storing electricity generated by solar panels was lead-acid batteries. It is the same type of battery that is used in motor vehicles and has also been used in off-grid energy systems for decades. For most homeowners this is the default choice as these batteries are the least expensive, and are tried and tested technology. They do however have a number of drawbacks.
| Advantages | Disadvantages |
| They are tried and tested | They take up a large amount of space and are extremely heavy |
| They are cheap and powerful | They emit hydrogen gas and are flammable when charging |
| They have a high output capacity | Shorter lifespan and need regular maintenance to keep them running safely and effectively. |
| hey usually have a depth of discharge of 60% meaning you can only use 60% of their capacity after which you will cripple their lifespan. |
2. Lithium Ion Batteries
The majority of new home solar energy storage systems use some form of lithium ion composition. They are evolving and fast becoming the most popular choice for on-grid solar battery storage for the foreseeable future.
| Advantages | Disadvantages |
| Lighter and more compact than lead acid batteries | More expensive than lead acid batteries |
| Almost completely maintenance free | They require protection from being charged or discharged too far |
| They have a higher depth of discharge (DoD) and as such a longer lifespan – they can handle up to 80% without negatively affecting their lifespan. | The batteries need proper management – without a quality system and software, the battery will quickly be wrecked. |
| Lithium is very reactive and have a very high energy density – a large amount of energy can be stored |
3. Flow Batteries
Flow batteries are relatively new to the energy storage market despite the technology having been used for years. They are called flow batteries due to the fact that they have a water based solution of zinc-bromide inside them. To increase the capacity of the storage system you need not add additional batteries, but only more electrolyte liquid – which can be replenished at any given time without interrupting power output.
| Advantages | Disadvantages |
| Main advantage is their scalability | They have a lower power density |
| They allow for quick discharge and charge | They are more complex than other batteries |
| They can idle for a long time without losing charge | Mostly for large scale applications |
4. Nickel Based
Nickel based batteries are normally used in large scale energy storage projects seeing as though the perform well in all types of temperatures. The most common nickel-based battery technology used is Nickel-Cadmium (NiCD) which is more suitable for off-grid installations due to their reliability and low maintenance requirements.
| Advantages | Disadvantages |
| High lifecycle – up to 2 000 recharge cycles | Low specific energy |
| Long operating life – up to 20 years | Very expensive – more expensive than lithium batteries |
| Good at handling power surges | High self-discharge |
| Low temperature friendly | Contains toxic material |
5. Which Battery Type is Best for a Solar System: Lithium Ion or Lead Acid?
As flow and sodium nickel based battery options are not really recommended for home use the main options you are left with is lead acid and lithium ion batteries. Although more expensive, the benefits of lithium ion far outweigh the benefits of lead acid batteries:
- Lithium batteries have a longer lifecycle
- A recommended depth of discharge of 80% or more, whilst lead acid batteries mostly run to 50% depth of discharge
- Lithium batteries are more efficient
- Higher efficiency results in the lithium battery charging faster and as such fewer solar panels are required
- Lithium batteries have a higher charge rate, which means they can be refilled much quicker than lead acid batteries;
- If you charge lead acid batteries too quickly they can overheat. In addition, the charge rate of a lead acid battery gets much slower when the approach full capacity.
- Lithium batteries are more environmentally friendly – lead and sulphuric acid can be unhealthy if discarded incorrectly and contaminate solid and ground water.
- It is more compact, lighter and sleek than lead acid batteries
Whilst the initial investment for lithium ion batteries might be more than lead acid batteries, their lifespan and performance more than make up for the upfront expense.