Solar energy is a popular alternative to traditional energy sources like oil, gas, and coal. While solar energy is environmentally friendly, it has some drawbacks. Solar energy is not always available in sufficient amounts, and it can be expensive to install and maintain.
The advantages of owning your own power plant
If you are not connected to the grid, you have one very important advantage – independence from the grid. You may even wish to be independent in the event that you already have a power grid connected. You don’t have to obey the rules set by the local power grid. You are not afraid of electricity price increases, accidents in the grid, breaks in the power lines, deterioration of power quality due to overloads in the grid.
If you are choosing a site for your home, you are likely to find that plots away from the centralized power grid are cheaper. Most people are not ready (either psychologically or due to lack of knowledge) to have their own power plant and be “their own power grid. Therefore, the cost of land is formed according to the demand for such sites. Having your own power plant and not being connected to the grid can be much cheaper than the cost of extending the power line and connecting to the centralized power grid. However, you have to be prepared for the fact that if you are not connected to the grid, you will have to pay for the purchase and maintenance of a renewable energy generating system
Off-grid systems can also have some advantages over running in parallel with the grid when it comes to system consolidation. Even though both systems are modular, it’s often easier to ramp up an off-grid system as soon as you can afford it. In fact, many owners of off-grid systems on a tight budget accept the norm of gradually scaling up the photovoltaic system and reducing the share of electricity generated from the diesel generator when adding solar panels. At lower voltages in the chain of solar modules (from 12 to 72V), it is possible to gradually add modules – from 1 to 4 at a time. Battery-free systems operating in parallel with the grid usually have solar module voltages from 150 to 600 V, and specific inverters have their own operating interval of the input voltage, as well as a certain dependence of the efficiency of this parameter. Adding daisy chains will require more modules and possibly replacing the inverter (or adding another one).
Unless you can afford a deliberately redundant system, stand-alone generation encourages you to use energy as efficiently as possible. This is a big advantage, especially if you care about your impact on the environment. The most energy-efficient homes are those not connected to the grid. When you need to get energy from a limited source, you’re bound to think about how to make the most efficient use of the energy you generate.
There are also many less tangible benefits to being off the grid. Including the satisfaction of using your electricity responsibly and understandingly. And maybe your neighbors will think you’re ahead of your time.
Disadvantages of off-grid systems
When you decide to disconnect from the grid, you are assuming some of the responsibilities currently performed by the local power grid that you want to opt out of. Our experience is that your dissatisfaction with the grid will be less the more of their responsibilities you take on. First of all, generating your own electricity costs money. If you are already connected to the grid, it is likely that an autonomous system with renewable energy sources will produce more expensive electricity for you. An exception might be if your region has special financial support measures for renewable power plant owners, or the cost of grid power is very high (or both).Here it should be noted that most financial incentive mechanisms for generation from RES are valid for systems connected to the grid and are not applicable for fully off-line systems with battery storage.
Of course, if you think about the long term, that changes the picture. But most people who think that disconnecting from the centralized power grid will reduce their energy costs are in for a disappointment. With a grid connection already in place, you don’t have to pay for the length of the power line and the connection to the service. This cost varies from region to region and can be up to 30$ per meter. If you need to pay for connection to the grid – you can already compare the cost of connecting to the grid and the cost of your own power plant equipment.
Secondly, the maintenance and repair of systems is a very important point in maintaining your own autonomous power system. When you pay your power bills, you are paying for the hard work of electricians (as well as accountants, bookkeepers, suppliers, managers, etc. personnel of the power grid) and consumables. If you are “your own electric utility,” you have to do the work yourself, plus bear the cost of buying all the necessary equipment and supplies.
Stand-alone systems use rechargeable batteries to store electricity. Batteries require regular replacement. The replacement period can range from 5 to 15 years (usually less than 10 years). And the batteries need to be replaced all at once. At the same time, industrial batteries with a longer life span can cost 3 to 4 times more than the batteries normally used. Replacement cost is not the only disadvantage, there is also the cost of maintenance and the time and effort involved in replacing a battery. There is also some environmental impact from the production, transportation, and disposal of lead contained in batteries.
There is also energy loss in the batteries. At best, the charge-discharge efficiency of batteries is 90%. This means that if you spend 10 kWh to charge a battery, you can get less than 9 kWh back. As batteries age, their charge-discharge efficiency drops. Battery efficiency also depends on temperature. Therefore, you will lose more energy in the batteries the older they are, as well as when the operating temperature deviates from normal (usually 25C).Compared to grid-connected systems, stand-alone systems have another serious drawback. It is the loss of surplus energy generated. When a grid-connected system generating electricity from renewable energy sources produces more energy than is currently being consumed in the house, this surplus can be sent to the grid. In this case, either the meter spins backwards, or the grid buys electricity at a higher price (depending on which incentive mechanism is used in your region. Unfortunately, no real mechanisms in place yet, and it is very difficult and expensive to legally connect a power generator to the grid). At the same time, the capacity of your solar or wind power plant is fully used at any time, regardless of your energy consumption. Nothing is lost, and the grid is a virtual battery with 100% efficiency. If you are completely off-grid, your surplus must be used – or it will go to waste. In most photovoltaic systems, the solar array simply shuts down when the batteries are fully charged. In most wind or hydroelectric systems, the excess energy is diverted to the ballast load (usually various water or air heaters). Knowledgeable off-grid owners are aware of this, and change their energy schedule depending on the availability of excess energy. For example, if you have a solar panel with enough power, you can start the washing machine in the middle of the day. But this behavior cannot be fully automated, and requires changing some habits when switching from saving to wasting energy depending on weather conditions.
Most stand-alone systems contain a backup diesel generator, and this is another big disadvantage of such systems. Power generated from a diesel generator is expensive (considering the cost of fuel, shipping, engine repairs, etc.). If you buy a cheap generator, you may find that you have to spend a lot of time and effort to repair it, and end up replacing it much sooner than you anticipated when you bought it. Not only do we wish you to be successful with your plans for your own renewable energy power plant, but we also wish you to be realistic and weigh the pros and cons carefully. Many families who live in their homes away from the centralized power grid know that such a life is not always a picnic. Social and family behavior with a time-varying energy source must necessarily be taken into account. Being off the grid is a pleasure, but it is also a responsibility. You either have to be willing to adjust your needs to the weather, or run a liquid fuel generator when your plans don’t match the weather. If you’re a city dweller who eagerly waits for the traffic light to turn green, imagine your condition when you have to wait for the sun to shine or for the mechanic to come fix your electric generator.
Advantages of grid-connected systems
Using renewable energy with the grid avoids many, if not all, of the disadvantages of off-grid systems. The grid is a large accumulator with 100% efficiency that can take all your excess energy. In addition, you can draw as much energy from this “battery” (practically) as you need. If you can’t afford a renewable power plant of the size that will provide all of your energy needs, you can only install a portion of it. If you’re completely off-grid, you need to generate all the power you need one way or another, and if you skimp on the size of your solar (for example) battery, it will cause you to waste a lot of fuel. When the big power plants supplying the grid run on fossil fuels, they at least use them more efficiently and with less noise and pollution than your home diesel or gasoline generator. If your solar power plant is connected to the grid, there is absolutely no need to be hard on energy and change your lifestyle. You can continue to live just as you did before you installed your own renewable energy power plant. You can get all or part of your energy from your own power plant, but your life and habits may not change.
If you choose to use a grid-connected system with backup batteries, you get the benefits of both. You’ll be able to be independent of the electric grid, and have all the benefits of off-grid systems. You’ll be able to continue to use your appliances during grid failures, and you’ll also be able to send the excess energy you generate to the grid.
With all types of systems with solar panels, wind or hydroelectric power plants, you lock in the price of the electricity you receive for many years to come. For example, if you install a solar power plant, you will actually buy electricity for 40 or 50 years in advance at a fixed price, and you will still be able to enjoy all the benefits that the centralized power grid provides us.
Disadvantages of grid-connected systems
One of the major disadvantages of grid-connected systems is that you have less incentive to conserve energy and energy efficiency. You plug in a variety of appliances and you don’t hear signals that the battery is about to run out, which causes you to waste a lot more electricity. You’ll get the most out of your renewable energy power plant if you can shift your energy consumption habits as if you were living with a stand-alone power plant.
Without batteries, you won’t have a backup power supply. But in most cases, it is a big disadvantage to have an expensive system and not have electricity when there are frequent blackouts and accidents in the grid. Therefore, we recommend isolating at least part of the critical load and providing it with power from backup batteries.
However, even a battery-connected system with batteries usually provides only a portion of the load during power outages. If power outages are long and the weather may often not be sunny, you may need a fairly large battery pack. This can make it expensive and reduce the efficiency of your off-grid power system.
For all grid-connected systems, it can be difficult to connect your power plant to the grid. It all depends on your local power company. Unfortunately, grid-connected power plants are still rare, power utilities are very reluctant to grant permission to connect a non-owned power source to the grid. You are sure to encounter incomprehension on the part of grid workers, who will not only demand a bunch of documents from you, but will also put you in all sorts of obstacles. Moreover, nowadays, the official permission to generate electricity and supply it to the grid requires a permit for technological connection of your power plant to the grid. This costs a lot of money. Much hope lies in the enactment of the federal Electricity Transformation Act, passed in 2007, which requires the grid to connect any power plant generating electricity from renewable energy sources if it is registered as a participant in the wholesale electricity market. The cost of connecting to the grid must be compensated from a special federal fund. And for each kilowatt-hour sold into the grid, the generator should receive a premium premium to the wholesale electricity price. However, this law is not working in reality. And this despite the fact that even the enactment of this law does not solve the problem of connecting to the grid for private homeowners – for them official connection to the grid remains almost unreal. If we act within the current legislation, it is necessary to obtain technical conditions for the connection of generating capacity to the grid, pay for technological connection, etc. All of this, in the end, for a photovoltaic power plant with a capacity of 1-5 kW is totally impractical.
Another unexpected difficulty was the lack of household single-phase electricity meters, which can reduce their readings if the current is fed into the grid. Most residential electric meters add up both the electricity consumed and the electricity supplied to the grid without regard to the direction in which the energy flows. Only some models of three-phase meters can take into account the direction of energy flow and make separate metering of the electricity consumed and supplied to the network. Therefore, we can only really talk about reducing consumption from the grid by means of solar network installations.
Cost estimation
So, how do you choose between a stand-alone and a networked system? Of course, it will only be your decision, which is based on both economic benefits and your value system. First, compare your costs for both of these systems. A battery-operated system typically costs 30-40% more than a battery-less, grid-connected system. Or maybe as much as 50%, depending on the batteries and other system components used. Another figure to consider, too, is the cost of connecting to the electric grid. It can be as close to zero if the line runs close to your home and the grid has power to spare, or it can cost you hundreds of thousands of dollars if your site is far from the centralized power grid. Compare prices from solar panel suppliers and from the local power grid. However, you need to compare more than just numbers here. There are examples where people have been billed several thousand (or even tens of thousands) of dollars for connecting to the grid. They ended up opting for an off-grid wind-solar system, and spending 3 times the money on it. And yet they got satisfaction from it because they were independent of the grid and their problems, and they didn’t get monthly power bills. Obviously, the initial investment was not a priority in their decision-they had other values. But they invested a lot of money and time initially, and will continue to invest to keep their system up and running. Other people choose to connect to the grid, in order to have all the benefits of being connected to the grid, while at the same time installing themselves a solar power plant, in order to reduce their energy consumption from the grid.
In any case, if you already have a grid, our advice is not to disconnect from the grid. Of course, it is up to you to decide what you want to do, and there are always cases where it is better not to take this advice. For example, if the networks don’t accept the surplus electricity you generate, or if the cost of electricity from the networks is very high. But, in general, it is better to combine the grid with solar panels. This will help you take advantage of the benefits of solar or wind power plants, causing minimal damage to the environment. Modern equipment offered by us allows you to maximize the use of energy from renewable energy sources, and at the same time to have a backup power supply and not have to obtain expensive permits to generate and supply excess electricity to the grid. At least until we have legislation in place that would require the grid to accept electricity from solar panels and pay a bonus not just to wholesale electricity market participants, but to every homeowner with a solar panel on their roof.
For more information on the different solutions to creating your own optimal green power plant, you can visit other sections of our website. Or just give us a call and our consulting engineers will find the most suitable power supply option for you.