Solar Panel Cleaning: Protect Generation and Assess Savings

How solar panel cleaning supports generation and potential savings

Solar panel cleaning removes deposits that block sunlight and may recover some lost generation, helping the system make better use of available light. The additional electricity may replace grid purchases or be exported; the effect on the bill depends on how the electricity is used and the system arrangement. The reviewed studies measure generation losses and panel output, not a uniform bill reduction for Israeli customers. ^{[1] [3]}

Keep four quantities separate: the electricity your appliances consume, the electricity your solar system generates, the additional energy recovered after dirt is removed, and the cost of electricity imported from the grid. An air conditioner or refrigerator does not consume less because the panels were cleaned. The home may import less electricity, or the system may export more, depending on consumption timing and its electricity arrangement.

What global estimates tell us about soiling losses

In September 2025, IEA PVPS, the International Energy Agency's Photovoltaic Power Systems Programme, published an estimate of 4–7% global solar energy losses due to soiling. This refers to generation lost because of soiling, not household electricity consumption. It is an aggregate estimate, not a guaranteed range of improvement from cleaning a particular roof. ^[1]

The December 2022 IEA PVPS report estimated that soiling caused the loss of at least 3–4% of annual global PV generation in 2018. It also highlighted differences between locations, seasons and even parts of the same installation. That older estimate should not be presented as a current Israeli measurement, or mixed with a measurement of instantaneous power output. ^[2]

This does not mean every system loses only a few percent. A global average includes relatively clean sites alongside heavily affected ones. Location, rainfall, dust sources and the distribution of deposits change the outcome. Even a credible global estimate cannot replace information from your own system. ^[2]

What a severe-dust study shows about loss potential

Under severe soiling, cleaning may recover some affected output, but the value varies with site conditions and exposure. A study by Zeedan and colleagues, published in Sustainability in 2021, analysed data collected over six months during 2017 on the solar laboratory roof at Qatar University in Doha. The tested panel was not cleaned during that period. ^[3]

The researchers used a model to estimate a power reduction of about 43% at an ambient dust density of 0.7 milligrams per cubic metre, under prolonged accumulation conditions. The comparison baseline was the model's predicted output of 70.85 watts at zero dust density, not the manufacturer's rating or an electricity bill. This is an estimate of power under defined conditions, not a measurement of 43% annual energy recovered through cleaning. ^[3]

The figure has important limitations. Filtering environmental conditions reduced 495 observations to 16 points in the final model. Its specified ranges were irradiance of 500–560 watts per square metre, air temperature of 28–37°C, relative humidity of 30–60% and wind speed of 3–8 km/h. Dust was measured in the air; the model assumed a relationship with deposits on the panel over months. It was not a direct, simultaneous comparison between clean and dirty panels. ^[3]

The authors note that the finding depends on site conditions and should not be broadly generalised geographically. It illustrates the loss potential at a dusty site left uncleaned for an extended period; it does not establish a typical improvement for an Israeli roof. A 7 June 2022 Bar-Ilan University announcement about a cleaning robot describes expected improvement but does not provide a measurement series or comparison baseline. Each source is best read according to the type of evidence it presents. ^{[3] [4]}

How to interpret percentages for losses and generation gains

To understand a percentage, check its comparison baseline. A soiling loss is the difference between clean and dirty production divided by clean production. A cleaning gain is that same difference divided by dirty production. Because the second denominator is smaller, the percentage gain is larger.

Here is an illustrative calculation. Assume a clean system would produce 1,000 kWh over a given period under the same conditions, while the dirty system produces 700 kWh. The difference is 300 kWh. That is a 30% loss relative to clean production. If cleaning recovers the entire difference, the gain relative to dirty production is approximately 42.9%.

Conversely, if cleaning increases dirty production by 30% and brings it to 1,000 kWh, the previous production was about 769.2 kWh. The loss relative to clean production was approximately 23.1%, not 30%. Both examples assume complete recovery of the difference. Not every actual reduction is caused by dirt, and cleaning is not guaranteed to recover it fully.

When additional generation can reduce grid purchases

The financial value of additional generation depends on how the electricity is used. Electricity consumed at home while it is generated may replace grid purchases, and exported electricity may earn payment under the system's arrangement. A battery, export restriction or inverter limit also affects the calculation. It is useful to distinguish increased generation from the actual change in grid purchases and the bill.

Continuing with hypothetical figures, not customer data: suppose the home consumes 1,600 kWh during the period, generation rises from 700 to 1,000 kWh, and there is no battery. Assume 60% of generation is consumed on site in both cases. Grid imports fall from 1,180 to 1,000 kWh: a reduction of 180 kWh, or about 15.3% of previous imports. Total household consumption remains 1,600 kWh. Of the extra 300 kWh generated, 180 replace purchases and 120 add to exports.

Even the illustrative 15.3% is not a prediction of total bill savings. To assess value over a defined period, multiply additional on-site consumption by the avoided variable electricity rate, add the applicable payment for additional exports, and subtract the cleaning cost. Check the actual arrangement and fixed charges rather than inserting an electricity rate or service price that has not been supplied.

How to assess your system and plan cleaning

A photograph of the panels helps assess their condition and plan the work. To understand a change in generation, compare similar periods: different weather can affect results alongside cleaning. The IEA PVPS report discusses measuring clean-to-dirty performance ratios and accounting for uneven deposits. If you need a precise numerical assessment, consult the system operator or an appropriate monitoring professional. ^[2]

For an initial decision, gather generation records, note the last cleaning date and record significant dust or rain events. Also check system alerts, new shading or signs of a fault, so you can distinguish dirt from other causes. Cleaning removes deposits from panel surfaces, but does not address a faulty inverter or damaged panel. A post-cleaning comparison is more useful when periods are similar and irradiance and temperature are taken into account. ^[2]

Cleaning timing depends on system condition and records, rather than a single schedule for every Israeli roof. Choose a method compatible with the panel manufacturer's instructions and site access. When inspecting or taking photographs, stay in a safe location; do not climb onto the roof or handle electrical components.

Arrange solar panel cleaning with MOLO CLEAN

To discuss solar panel cleaning and tailor the scope of work, send the location, panel count or approximate area, photographs taken from a safe position and a description of access. Mention the last cleaning date, visible deposits and any special instructions from the manufacturer or installer. Available generation records can help assess the system.

MOLO CLEAN provides solar panel cleaning and has operated for more than eight years. To discuss the scope and request a tailored quote, call 0539306139 or message WhatsApp at 972539306139. The potential effect on generation and bills can be assessed using the system's records and electricity-use patterns.

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