Solar Panel BER Uplift Calculator

Notes

BER Grading System Update: 24 May 2026

Ireland introduced a new BER grade cutpoint system on 24 May 2026. This calculator now uses the new cutpoints as the primary grading system. An equivalent old-system grade is shown alongside your input for reference when comparing against BER certificates issued before that date.

Key changes: a new A0 grade was introduced (≤ 42 kWh/m²/yr; no fossil fuel usage), and the A–G cutpoints were adjusted. The old sub‑grades (A1/A2/A3, B1/B2/B3, etc.) have been replaced with simpler A, B, C, D, E, F, G single‑letter grades.

Accuracy & a conservative (lower-bound) estimate

This calculator follows the official DEAP 4.3 methodology (the version in use for BER assessments from 24 May 2026). The solar generation, the split between electricity you use yourself and electricity you export, and the conversion to primary energy all use DEAP 4.3's exact constants and month-by-month method.

The result is deliberately conservative. Your home's electricity demand is estimated from its floor area using DEAP's standard household figures, assuming you do not use electricity for space or water heating. This is the assumption that produces the smallest credible BER uplift, so your real assessment should come out the same or better, essentially never worse. Homes with a heat pump or electric heating will typically see a somewhat larger uplift than shown here (potentially notably larger with a heat pump), because self-used solar is worth more than exported solar under DEAP.

For the greatest accuracy, enter your numeric BER grade (kWh/m²/yr), not the letter grade. Specify floor area according to your most recent BER Advisory Report. You can get your Advisory Report by entering your electricity meter number (MPRN) to the National BER Register online.

About BER Assessments

Accuracy of BER Assessments varies widely. You'll typically get a higher and more accurate BER grade if you can supply proof documents showing the details of all energy upgrades carried out on your home over the years. You need to re-supply these documents every time you get a new BER Assessment, so keep them in a safe place for the future. This calculator assumes that you provide proof of the details of your solar panel system to your BER Assessor, and that all other factors are the same before and after solar panel installation.

How Much Solar Will Save You

Click here to find out how much solar panels could reduce your electricity bills, and find the best electricity tariff for solar panel owners.

Methodology

Calculations follow the DEAP 4.3 method (DEAP 4.3 Workbook v1.0, valid from 24 May 2026). BER grades reflect primary energy. Monthly solar generation is calculated from your panels' peak power, orientation, tilt and overshading, then split each month between electricity used in the home and electricity exported to the grid. Under DEAP 4.3's Table 12.1, each unit of self-used solar electricity displaces 1.5 units of primary energy, while each unit exported counts for 1.0. The self-use/export split is determined month-by-month from your home's electricity demand using the DEAP 4.3 formula (equation M7).

Home batteries do affect your BER. A battery lets you use more of your own solar generation rather than exporting it, and self-used electricity counts for more primary energy. Enter your usable battery capacity (DEAP caps the benefit at 15 kWh).

Understanding How Solar Affects BER Grades

Solar almost always results in a better BER grade. However, the size of the improvement depends on several factors:

• Home size: Solar has a proportionally bigger impact on the BER grade of small homes
• Solar panel system size: The bigger your solar panel system, the more it will help your BER grade
• Light exposure: South-facing systems with minimal or no shading have the biggest impact on your BER grade

Remember that other factors unrelated to solar, like proof documents about the insulation quality in your home which you supply to your BER assessor, also impact your BER grade. This calculator is only reliable assuming those other factors are "held constant".