Ever thought about switching your home or office to a solar energy system but don't know where to start?
We collaborated with Cedar Solar to bring you the most important things to consider before you start. We cover:
- Understanding the basics of how solar works
- Which type of solar system do you need?
- How to get energy-efficient first
- How to calculate how much energy you use
- Information about shading
- Installer experience
- Hardware guarantees
- Battery cycles
Understand the basics of how solar works
When the sun shines on solar panels they produce DC power. Solar Panels do not work with the heat from the sun, but rather the light. A 300w solar panel can produce about 300w of energy per hour when the sun shines on the panel. Panels should face north in the southern hemisphere and should be angled correctly to maximise the hours the sun shines on them. In Southern Africa we get about 4 to6 hours of strong sunshine (peak sun hours) per day.
In an off-grid/back-up system, the DC power is sent to a charge controller and from there to a battery bank for storage. The charge controller manages the charging of the batteries. An inverter then pulls power from the battery bank and supplies power to the loads (household appliances) when the sun does not shine. It converts 48V DC power to 220V AC power that home appliances use.
Which type of solar system do you need?
It is important to decide what you would like to achieve by switching to solar. Do you want power during load-shedding? Do you want to save on your energy bill? Do you want to live a more sustainable life?
The most common systems are:
This means no connection to NamPower. This is the most expensive system because you need a large battery bank to run your appliances in the evenings and/or on cloudy days. With an off-grid system, load shedding is a thing of the past because you are not connected to the grid (NamPower). You might need a backup generator (or increase the battery bank size) if there are a few days of cloudy weather. Getting off the grid completely is expensive. A full off-grid system can cost from N$200 000 to N$300 000 for the average homeowner. You will also need to focus on being energy efficient meaning giving up luxuries like underfloor heating, heaters etc.
Grid-Tied (On-Grid) System
This means you are still connected to NamPower. For a grid-tied system, you don’t need batteries. The power the panels generate is used immediately by appliances. This reduces your energy bill but does not necessarily eliminate all energy costs. Feeding back into the grid is not allowed in Namibia. This means you will only save money during the day. This option works best for where consumption occurs during the day (i.e., offices). The average cost is N$30 000 – N$100 000+
This system is a combination of a grid-tied and off-grid. You are still connected to the grid, but with a smaller battery bank to get you through load shedding & you will save money during the day. The system can be set up to keep batteries at 100% and then run your daily loads from the panels. This is the most popular system for Namibians and the main goal is getting through load shedding, but you are also saving money during the day. The average cost is N$80 000 to N$250 000.
This system does not need solar panels. The batteries are charged by the grid when grid power is available (from a wall outlet/DB Board), battery power is then used when the grid fails (load shedding). This is your most cost-effective backup solution, but you do not save money with this solution. The average cost is N$25 000 to N$100 000.
It is better to get energy-efficient first
Appliances that draw a lot of power do not work well on solar systems. Your first step is to get as energy efficient as possible. This includes changing your electric geyser to a solar geyser/gas geyser. Next, replace your stove and oven with a gas stove and oven. If you use equipment like power tools & welding machines, it is best to run these on a generator and not on your solar system. Replace all your lights with LED lights. Also decide how you will use heaters in your home. Heaters can consume 2000w an hour and are not advised on an off-grid installation. In a hybrid system, some plugs can be wired for these high consuming appliances. These will still run off the grid and your other appliances off solar power.
Now your installer can design a smaller solar system for the remaining appliances. This is the most cost-effective way of doing things. Get energy-efficient first, and then install a smaller system for your remaining appliances.
How much energy do you use?
The best way to establish this is to install an energy meter (SCOUT) for a week or two in your home. You will then see exactly what your total consumption and peak usage is. You will also get a breakdown between daytime and evening consumption. Your installer can very accurately design a system based on this information. This is the most accurate way to size a solar system.
Alternatively, you can provide your installer with utility bills and an appliance list indicating how long you want to use each appliance every day and they can design a system according to that.
This information is particularly important when sizing a solar system and will determine the number of panels needed for the size of the inverter and size of the battery bank.
Solar Panels & Shading
Is your roof facing north? A north-facing roof is the best for solar panels here in Southern Africa. Panels can also be placed west or east. It is important to mount your panels securely using a high-quality roof mounting system. There are different systems for different roof types the most common being tile and IBR (corrugated iron roof). Also note, any shade on panels will influence power generation quite dramatically. A little bit of shade can reduce the efficiency of a panel by at least 30%. Shading from trees, chimneys and other buildings need to be considered when designing a system.
A solar system is a big investment. Make sure your installer has at least 3 years’ experience and quality installations. Ask for references of previous clients. There are too many inexperienced installers that deliver non-performing systems and unsafe installations.
Ensure that you get a good guarantee on all your solar components. A good guarantee for solar inverters and chargers is 5 years. Lead Acid batteries usually have a 2-year warranty and Lithium-Ion Batteries a 7 to 10-year warranty. Most grade A solar panels have a 25 to 30-year warranty. If an installer offers noticeably short warranties (1 to 2 years), there is a reason and the products used may be inferior.
Not all batteries are made the same. They have different life spans, and this is indicated as cycles on the spec sheets. A cycle is when a battery goes from full to empty to full. This is considered 1 cycle.
When comparing batteries don’t just look at Amp Hours. A 100 Ah with 1000 cycles is not the same as a 100Ah battery with 2500 cycles. When comparing battery prices calculate the cost per cycle and do the comparison. Do not merely look at the price of the battery. The cycles need to be considered.
Compare apples with apples
Research the brands to see what you are buying. A good example is cars. You get a 2 litre Tata and a 2 litre Toyota. Both have the same capacity but there is a difference in price, quality, reliability, technology, warranty and more. Research the brands that the installer suggests. How long have these brands been around? Do they offer warranties up to 5 years? Google some reviews of the products.
Ask other installers what they think of brand X, or why they prefer a certain brand? In solar just like in most industries, you get what you pay for.
You would not buy a car without a fuel gauge, speedometer and warning lights. Why purchase an expensive solar system without monitoring? It is important to be able to monitor your system to ensure it performs optimal. A good monitoring system also picks up system problems early enough before any hardware suffers damages.
What you can and can’t run on a solar system.
Some high consumers will overload your solar system and shorten the lifetime and capacity of your batteries. Therefore, we do not recommend geysers and stoves on solar systems. If you have many power tools that use a lot of electricity it is better to turn these appliances off a generator. If you have appliances you are unsure of, your installer can advise you. You should be careful with higher consumers like heaters.
Safety extras include: Fuses, breakers, surge arrestors, proper grounding, emergency stop, correct cable gauges, Certificate of Compliance etc. This is usually where inexperienced installers don’t know which safety measure to put in place and unreliable installers cut corners to make the system as cheap as possible. But this puts your family’s lives at risk. If an installation is done incorrectly it can be extremely dangerous. It is worth paying a bit more for the peace of mind that your installation is up to code and has been signed-off by a master electrician. You need a COC for your insurance company and to be compliant.
Most of the major banks offer solar loans. The loans usually fall under the personal or residential loan division at the bank. Most of these loans offer a 5 to 10 year payback period. It is best to phone your banker to find out how they structure their solar funding.
We hope this information helps you to understand solar better. It can be a very intimidating decision for a homeowner. Find an installer with a good track record that you can trust. Make sure you have an accurate consumption profile of your home or business and invest in quality components. Then you will have a solar system that performs like it should.
About Cedar Solar:
Cedar Solar specialises in solar energy with a focus on rooftop PV systems (the products we stock) as well as solar water pumping solutions.
They were established in 2010 in Namibia, opened an additional office in Johannesburg and currently service the whole of Southern Africa with an extensive network of independent resellers.
They pride themselves on only using reliable solar hardware with great performance guarantees. Their technical team can guide clients from the initial system design through to installation and maintenance with the aim to simplify the process of switching to solar.
💼 10 years in business
⚡️ 4 megawatts installed
☁️ 35 000 tons of CO2 offset
📍 18 African countries served
Contact Cedar Solar:
+27 11 794 4664
Contact installers that specialise in home/office installation:
📞 Fortune 081 141 2650
📞 Stanley Tjirare 081 741 6466
📞 Heinrich Kassen 081 127 6557