Here, you’ll find answers to some of the most commonly asked questions about our solar panel and battery solutions. Whether you’re a current customer or considering becoming one, this page is a great resource for learning more about our products and services. If you don’t see the answer to your question here, please don’t hesitate to contact us. We’re always happy to help!
Planning for a solar PV system will require you to analyse your electricity use, implement energy efficiency measures, decide if you want to operate your system entirely off grid or use a hybrid solution, and then finally select, the technologies to help you meet your objectives. And because your system is going to be working for the next 20-25 years, you need to be sure about working with a supplier that has the network, financial stability, product quality and warranties in place to maximise your investment. Reputation, credibility and the expertise of your renewable energy partner are fundamental to you realising the maximum benefit from your solar PV investment.
Implementing energy efficiency measures before you buy your PV system will reduce your electricity use and allow you to buy a smaller and less expensive system. For example, converting geysers which are your biggest electricity users to solar or heat pumps, installing LED low energy lighting, using gas for cooking and so on.
Calculating your electricity needs is the first step towards getting PV ready. A thorough examination of your electricity needs helps you determine the following:
By conducting a load analysis, One Energy will record the wattage and average daily use of all of the electrical devices that are plugged into your central power source such as refrigerators, lights, televisions, PCs, power tools, machinery and computer equipment. Some loads, like your refrigerator or electric fencing, use electricity all the time, while others, like power tools or large format printers, use electricity intermittently, known as selectable loads. Based on this we work out what your essential and non-essential loads are (the essential load refers to all the appliances/circuits that must stay on and back-up in a power outage), and can then design the right size system and back-up for your needs.
Some providers will ask you only for an electricity bill and attempt to provide a PV solution based on this, but the approach is fundamentally flawed and inaccurate since your bill cannot reveal day and night usage, selective loads or peak demands which need to be factored into your PV solution. A thorough load analysis is a must. We’ll visit your premises, set-up loggers on your electricity distribution board for at least a week to ten days, providing you with a comprehensive view of where your electricity usage is going, and what steps we can take to help you reduce it. We will also be able to provide a very accurate indication of what your savings will be depending on what size system and the solutions we specify for you, so there is no shooting in the dark.
Many people believe renewable energy is too expensive without actually doing their homework. The reality is that the cost of renewable energy solutions has come down significantly over the last few years. When we take them through the costs versus the savings and the fact that their savings can even finance their move to renewable energy, most are stunned at how absolutely affordable it is.
In fact, on a monthly repayment option on a bank loan, in many cases the monthly finance payments are covered by what they would be paying on electricity costs anyway. Once paid off, you’ll be smiling even more! Your best option and ROI is of course on an outright purchase, and many people use their savings or bond to purchase their solar solution.
If we look at a typical PV system, your initial capital layout would be in the beginning when you purchase the equipment and on average takes around 5 years to offset the costs, but then for the expected 20+ years of the lifespan of your panels, you will get free electricity. The initial upfront cost is the only cost involved with solar. After that, because there are no moving parts, the maintenance on the system is very low. Once fully paid, you have an incredible investment and asset for your property that keeps saving you thousands of Rands each year, for many years to come. And you’ll have a highly efficient, green home or business which is an absolute win. Another advantage of PV is that it is entirely scalable and can be ramped up as your requirements demand and, more importantly, as your budget allows.
A 5kW hybrid inverter, 10.8kWh li-ion battery and 5.4kW solar array will take a home using around 25-30kWh per day to around 90% off the grid. A system that takes care of 80-90% of your electricity needs is the best option from a financial perspective – with a connection to the grid to recharge the batteries during cloudy/rainy weather.
The last 10% to get entirely off the grid can prove very costly. An entirely off-grid system would need to be sized at least three times larger than a grid-tied system that uses Eskom/council as a backup when there is extended inclement weather. While adding a generator can charge up batteries, this comes with the ongoing costs of fuel, system maintenance and emissions.
Your essential load consists of the appliances and equipment that you want to be able to power up in an outage while non-essential is exactly that – items that are not necessary or vital during an outage. By splitting your loads, you are able to use your batteries for longer to power up the essential equipment. Secondly, you also reduce the capital outlay needed on a bigger PV system and battery capacity if you were to try and power up everything in your home/office.
Essential loads are typically your lights, TV and routers, fridge/freezers, security systems, laptops and so on. Non-essential loads comprise of anything with an element (geyser, kettle, dishwasher, electric oven/stove), underfloor heating, heaters, aircons, heavy machinery, pool pumps and so on.
The amount and duration of battery back-up is dependent on two factors – the size of the battery bank and the size of the load drawing power from it – in other words how many appliances you have running at the same time, and the total wattage being drawn by these appliances. It’s one of the reasons why we split essential and non-essential loads, to extend the battery capacity.
For purposes of this exercise, we used one 3.6kWh li-ion battery which allows for an 80% depth of discharge. This means that once your battery is discharged to having 20% power left, it is automatically disconnected by the inverter to protect your battery’s lifespan. You can add additional li-ion batteries if you require more back-up.
Estimated battery running times based on a single 3.6 kWh li-ion battery:
Li-ion batteries have a phenomenal life span – with 6000 cycles+ at an 80% DOD – that’s a lifespan of 16 years (based on one cycle per day)! You can also expand your li-ion battery bank at a later stage and add more batteries within a certain time frame which you cannot do with outdated and cheaper lead-acid battery technology, which also only allows for a 50% depth of discharge (DOD). Essentially this means you can only use half of your lead-acid battery’s capacity, and the lifespan is 2-3 years at absolute best. With load shedding at stage 4-6, you’ll be very lucky to see even one year lifespan out of lead acid batteries. Don’t waste your money!
Here’s a rundown on the two technologies:
The new cost of a Lithium-ion battery system keeps coming down and has already reached a point where cost over time is much less than the rate you can buy power from Eskom or your council. Longer cycle life, cost per kW and no maintenance costs makes li-ion batteries a far better option to outdated lead acid technology.
Looking at an average electricity bill of R3000 per month, a family of four could expect to conservatively save about 30-40% of this bill by installing a correctly sized solar geyser
That’s R900 per month which is R10 800 per annum. Your solar geyser will completely pay for itself in under three years. From day 1, you will cut your electricity spend to Eskom by around 30% – every month. No other investment that you consider for your home will give you anywhere near this return. And you’re one big step closer to getting off the grid step-by-step.
Solar water heaters use the radiation from the sun to generate heat. The size of the solar panel will determine how much energy can be collected from the sun. Today, solar systems are installed with very smart timing systems which allow you to specify time zones for when you want to have hot water, for example at night between 6pm and 9pm when you take your bath, and again in the morning between 5am and 8am. Your system will work to ensure that you always have hot water during these times to the specific temperature. If the temp drops to below your specified requirement and there’s no sunshine at that time to reheat it, your system will kick back to the geyser element to supplement your hot water. It will only do this if necessary, so the savings are significant.
When going solar, as a rule of thumb, each person in the household uses around 70 litres of hot water a day. Check with your supplier about the size and the power output of the system. An under-sized or low efficiency system will result in insufficient hot water and a poor realisation on electricity savings, defeating the whole purpose of why you bought the system.