Winter is fast approaching and most solar panel owners will be dreading the drop in solar power output that comes in the cooler months. With shorter days, more cloud cover and the sun shining at a different angle, it feels inevitable that solar generation will drop by up to a third. But don’t despair yet, there are things that can be done to make sure your panels continue operating as efficiently as possible all through the winter.
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First, let’s dispel some myths about owning solar panels in winter. For one, winter weather doesn’t necessarily mean less solar power - in fact, your solar panels will function better in cool, sunny weather than they will in the summer heat.
Solar panels are tested at 25 degrees Celsius, so for every degree the temperature climbs above that, the panel’s output efficiency is reduced. In that regard, winter weather has an advantage over summer, though it still needs to make up for the winter roadblocks of shorter days and increased cloud cover.
With that in mind, here are some ways you can even further offset that winter drop, starting with the most low-tech solutions and working up to the ones that might require a little extra investment.
Keep Your Panels In Top Shape
While you should be taking good care of your solar panels year round, autumn is a particularly good time to give them some extra attention. Winter is when you’ll be needing that little boost after all.
If you haven’t done so recently - and if it can be done safely - you should give your solar panels a good scrub in case of any built up grime, dirt or other unwelcome additions to your panel like spots of bird poop. You should avoid using harsh chemicals or rough brushes to clean PV panels. Instead, use some warm water and a sponge wrapped in a cloth, or a soft brush. If you can’t get to your solar panels easily (or if you just don’t have the time) contact your installer or supplier and see if they can recommend a service for routine maintenance and cleaning.
If you live in one of the few parts of Australia that is prone to snow, you may want to invest in a brush designed to move snow from roofs (and solar panels). Aside from physically covering the panels however, snow shouldn’t damage or otherwise adversely affect your solar system at all.
Catch The Winter Sun
Now is also a good time to make sure your panels are still getting all the sunlight they can. Generally, your panels should be receiving full sun from 9am until 5pm. Taking into consideration the angle of the winter sun, you may find that stray branches or overgrown trees are now shading part of your panel array. If you can, trim any branches that may be interfering with your precious sunlight.
While not all setups are capable of changing the angle of solar panels, now is the time to do it if yours are adjustable. Because the sun hits your panels at a different angle in winter than they do in summer, you can easily increase your energy output with a single adjustment to the panels’ tilt. Some people do this twice a year - summer into winter and then back again - while others change the angle for all four seasons. No matter how often you choose to change the tilt, you can find a resource for the best angle based on your location and the time of year here.
Don’t Just Set And Forget
Now that you’ve run through the basics of setting your solar panels up for winter, it’s time to look at what more you can do to squeeze every last drop of energy out of your investment. If you want to get more hands-on with your power, it’s time to look at monitoring software.
Your system may have come bundled with monitoring software, otherwise you’ll need to look into retrofitting or upgrading what you already have. Regularly checking your monitoring software is the best way to make sure your system is always performing at peak efficiency.
Notice a sustained drop in output that doesn’t match the weather? It’s time to make sure you don’t have a stray branch shading your panels, or a spot of grime getting in the way of your precious solar energy. If nothing is obviously wrong with the panels, it might be time to get a professional in to check for less obvious faults.
For those of you in Victoria with grid-connected solar systems, AusNet Services will send an SMS when their smart meter detects the system is no longer feeding energy back to the grid. If you get an SMS like this, it's probably time to check out your PV system. The message also links back to a troubleshooting fact sheet from AusNet Services' to help with this.
Central Inverters VS Microinverters
If you’ve already got solar panels installed then you’re generally stuck with the type of inverter you have, unfortunately. If you’re just looking at getting a system putting in, however, you’ll want to consider the benefits of each type. Here’s a quick rundown.
In a solar PV system, your inverter is responsible for converting the solar panels’ direct current (DC) power into alternating current (AC) power that can be used to run your house, or to feed it back into the grid. In a typical solar array a single central or ‘string’ inverter is used to convert DC to AC. While this is generally the simplest and most cost-effective style of inverter, it comes with a couple of major drawbacks.
When running through a single inverter all the solar panels in your array act as a series circuit. What this means is that your array is only ever as strong as the weakest-performing panel. If one panel is partially shaded and drops to 50 per cent efficiency for example, all your other panels will only give 50 per cent of their potential. If the angle of the winter sun means your solar panels end up even partially shaded for some of the day, this can be a problem.
The alternative is a microinverter system. Microinverters are exactly what they sound like - downsized inverters that sit directly beneath your solar panels, allowing the system to connect in a parallel circuit. This way you can squeeze the most out of every solar panel regardless of how well the others are functioning.
Microinverters are also easier to install and replace, though they do have a few problems of their own. Firstly, they’re more expensive than traditional string inverters. They’re also less efficient, but for many systems this efficiency will be more than made up for by allowing you to get more out of every single panel.
Store The Winter Sun
The last thing you can do to get the most from your solar this winter is something you may have already looked into if your solar panels generally perform well - battery storage.
Connecting a battery to your PV system is the next step up in home energy, and can even be a step towards making your household energy independent. When winter brings so many cloudy days and shorter hours of sunlight, storing the energy you do collect on good days can be vital to your energy efficiency.
Home batteries can generally be retrofitted to an existing solar PV system – though if you’ve yet to invest in the actual solar panels you can also get everything you need installed in a single package. All you need to do is decide what battery is going to work best for you, with options ranging from the sexy slim-line Tesla Powerwall to the adaptable, modular design of Enphase’s home battery.
Tesla's Powerwall is a 7kWh lithium-ion battery designed to store excess energy, whether it's off the grid or from a home's solar panels. The Powerwall is not the first or only innovator in battery storage though — and it won't be the last.
As the name that brought home batteries into the spotlight, Tesla's Powerwall to many is the obvious choice. With the Powerwall 2 now on the market, and Tesla updating its app to allow Powerwall owners to monitor their home energy systems, it’s definitely an attractive choice. The Powerwall 2 is one of the higher capacity home batteries on the market, being able to store 13kWh and deliver 5kW of peak power. It’s also one of the most cost effective batteries at $8000 (not including installation or extra costs).
If you’re after even better cost efficiency, however, an Australian-made battery from a company called Ampetus Energy is actually the quiet winner in that regard. It’s called the "Super" Lithium Battery and at a price of $2,300 for 3kWh of storage, it’s great for residential solar arrays that don’t actually need the Powerwall's huge capacity.
Another option is designed to make sure you have exactly as much (or as little) storage as you need for your particular home and your unique solar system - Enphase’s modular battery. While Enphase is best known for its microinverters, it has recently taken that same microinverter technology and used it to create a modular battery.
If you’re planning on installing an Enphase battery, the idea is to first couple your solar system to the company’s monitoring software, allowing you to find out exactly how much storage capacity your house needs. At 1.2kWh per modular battery, you can get it down to a pretty exact number and you can always add more if you need it later. Each module will set you back around $2000, fully installed.
Another interesting, Australian-designed take on the home battery is Redflow’s Z-Cell. Spurning the traditionally accepted lithium-ion battery, the Z-Cell is built around a zinc-bromine flow battery. One of the biggest advantages of this technology is that it is much safer, especially at the higher temperatures Australia’s summers can throw at us.
It’s also far more durable, able to retain its full storage capacity for as long as 10 years without degrading. This makes it a great choice for those who are looking to run a good deal of their household energy through the battery, or moving off the grid entirely.
Of course, these are just a few of the many, many battery options on the market, but one thing is for certain – battery storage is the way to go if you want to increase your energy independence.
If you’re dreading the inevitable drop in output from your solar panels this winter, there are a number of ways to bolster performance – from high tech products to simply scheduling a weekend for some routine maintenance. Do you do anything else to prepare your solar energy setup for the weekend? Let us know in the comments!