In this article we explain you why Solar Photovoltaic with Energy Storage is a compelling alternative to unsustainable net-metering and increasing electricity tariffs, for achieving energy independence and self-sufficiency, and why you should consider it.
To guide you through the reasons behind this proposition, we are going to cover some basis of solar photovoltaic generation at the household level and how it is used and shared with the grid (utility companies), as well as the existing alternatives.
Lets use an example for this purpose: After a solar assessment is conducted, it is found that a rather energy efficient family household of 4 requires approximately 14.4 kWh/day or 5256 kWh/year for fulfilling all its electricity needs, including heating, as the house for this example uses a heat-pump for that purpose. A 6.4kW system is then designed to produce enough electricity for meeting such demand, based on the known solar resources for the location where the household is located, and again, for this example, such location is Riga – Latvia in the North of Europe.
Of course, in a Nordic location such as Riga, the electricity generated by the solar photovoltaic system is produced in larger amounts during the long sunny summer days and during the hours when the sun is shining, whereas during the winter the electricity produced by the same system is significantly diminished due to the shorter and often overcast days.
However, unlike the photovoltaic electricity generation, the electricity consumption is ubiquitous year-round, and it occurs 24/7 despite that it fluctuates based on the habits of the household/consumer.
So, how then a solar photovoltaic system can supply electricity during the night or during the days when the production is very low due to weather?
There are typically two ways:
- By being off-grid and having the system connected to an Energy Storage System (batteries). An off-grid system is an option when the grid is not available, for example in a remote rural area.
- By being connected to the grid under a net-metering agreement.
We will discuss the second option, as it is our intention to inform the segment of the population that lives in urban areas that are already connected to the grid. A solar system connected to the grid under a net-metering agreement allows to send to the grid the difference between the electricity produced by the system and the electricity used. This electricity is then returned from the grid when the solar system doesn’t produce. This is possible by means of a bi-directional meter. This system doesn’t require batteries as the grid is acting as such!
For example, in any given day during the summer months, the system produces more electricity than is needed, and in this case, the non-used electricity is sent to the grid as Wh credits; conversely, in any given day during winter months, the opposite occurs, and the Wh credits sent to the grid during those summer days are then sent to the consumer; and likewise on a daily basis as day changes to night.
Electricity imbalance and the increasing need for energy storage
As more and more homes install solar panels on their roofs and the excess electricity generated by these photovoltaic systems is collected by the utility company, the utility company must allocate such electricity to fulfill the night electricity demand and of all the customers regardless of these to produce their own solar electricity or not. This doesn’t represent an issue during the summer, but without utility-scale energy storage, a challenge emerges in the winter when the solar production is very limited.
What we are seeing now in many jurisdictions as more and more households opt for solar photovoltaic systems, is the occurrence of an imbalance that makes the net-metering system unsustainable. The result of this is that the credits in kWh that a household would have accumulated from their solar production and were given to the grid (utility company) are now returned with a variable tariff, and this situation consequently makes less attractive the net-metering option or more specifically the net-metering option unless energy storage enter in the equation.
Grid connected systems with Energy Storage System (ESS) under a Net-metering agreement
In this scenario a household produces and stores electricity, and the remaining non-used electricity can still be sent to the grid for kWh credits. Considering the electricity grid becoming increasingly imbalanced and moreover becoming unsustainable, this alternative appears to be as the best option.
In a system such as this, the electricity produced and non-used is stored for later use. If the solar photovoltaic system is big enough for fulfilling the requirements of energy consumption of the household, then the ESS as it is modular, can store as much energy as needed to meet the electricity demands. Should the demand exceed the limits of the stored energy capacity of the batteries, since the system is grid-connected, the grid can still cater for any supplemental electricity that might be required.
The benefits of a system such as the BLUETTI ESS modular EP600 paired with 2 EB500 LiFePO4 batteries, of nearly 5000 Wh of energy capacity each), go beyond the fact that can store electricity, they have an inverter incorporated and can produce electricity for pretty much all the loads that are used in a typical household, as well as being a form of power and emergency backup. So, in short, these systems improve energy resilience while reducing energy costs to homeowners.
If we had to list some of the strengths of these systems, they can be summarized as follows:
· Advanced LiFePO4 battery technology, providing long cycling life, estimated to 3500+ cycles with an 80% depth of discharge. That means around 10 years of constant use bringing the batteries down to 80% of its capacity at the end of this cycling period.
· Modular and scalable, easy expansion, easy transportation, and easy installation/connection.
· Intelligent BMS, battery monitoring and protection system, short circuit protection, wireless communications via APP.
· 10 years manufacturer warranty.
· Compatible with already existing solar system.
The costs and the Return on the Investment
The issue now becomes the cost of a hybrid system like this, which incorporates a solar PV array and BLUETT ESS EP600 + 2 EB500 batteries, and above all, what would be the return on such investment?
Production of a 6.4 kW photovoltaic system in Riga, averages: 15.1 kWh/day or 5506 kWh/year. Source: bvwatts.nrel.gov
Average consumption of a 4-person 2 story family household that uses energy efficient appliances and heat-pump for heating: 14.4 kWh/day or 5256 kWh/year.
Going back to the initial example of a home that requires 5256 kWh for fulfilling the needs of the household in a year, a solar PV system of 6.4kW paired with ESS EP600 and 2 EB500 batteries (that together have a capacity of nearly 10kWh) could meet all the electricity demand of the household.
How would that work?
Typically, from May to September the hybrid system will produce more electricity than it is required (and that the 2 EB500 batteries can store for later use). Undoubtedly during this period, the dependency from the grid will be minimal and will be limited to when extended periods of cloudy/rainy days occur. Thus, the system would be able to provide almost full energy autonomy to the household. In this case, the excess electricity that is not consumed is transmitted to the grid and in turn converted to Wh credits for later use.
In the other hand, from October to April, when days are shorter or prolonged periods of overcast weather are common, and consequently, when the solar PV production is low and the batteries are not fully replenished from the photovoltaic production, the system will have the ability to get supplemental Wh credits from the grid, though these will come attached to a tariff*.
For this example, the 6.4 kW solar panel array coupled with a BLUETTI ESS EP600 + 2 B500 batteries would correspond to an investment of approximately 17500 Euros (2023), without accounting for any government rebate (which would make the investment lower). By using an average electricity bill of 250 Euros as a reference**, the result is a ROI of 5.8 years***.
*Each case is different, and variables such as the electricity tariff attached to the Wh credits provided by the grid are not definite.
**A 250 Euro electricity bill is a monthly average for the same household in the scenario of being solely dependent of the grid.
***This result does not consider any increment in electricity costs due to inflation, which in the long term would favor the hybrid solar system as shown in the example.
We invite you to have your case assessed by a specialized solar company. In the Baltic countries, we work with the company SunGo, which can provide a solar assessment and guide you towards the best solution and more importantly a cost-effective one.
