Insulate First: Reducing Solar System Size and Cost in Pakistan

We’ve seen many people in the last couple of years contacting us regarding insulation. They are almost always partway through their solar journey, with quotes and a system size in mind. They just want to get rid of their electricity bill. Almost none of them will have asked “how much am I wasting on electricity before my panels are even doing anything?” In most Pakistani buildings we’ll find you’re wasting quite a lot of electricity, most of it on cooling.

Order of Importance

Solar systems are sized based on the amount of electricity your building consumes. The more you consume, the more panels, inverter and (if you want to use it at night) batteries you’ll need. Every unit of electricity you save, you don’t need to produce or store.

Insulating the building will reduce the demand by keeping the heat from entering your building through the roof and walls. Therefore the air conditioning won’t need to work as hard. This will reduce the total amount of electricity consumed meaning you can fit a smaller and cheaper system. This is like patching up a leaky tank instead of upgrading your pump.

Electricity Use

In most residential, office, school and small commercial buildings in Pakistan, air conditioning will take up the biggest single usage of electricity throughout the long summer months. In cities like Karachi, Lahore, Multan etc, air conditioning will be running for many months of the year with peak times during the afternoon when the roof is at its hottest.

The main issue here is the roof. An uninsulated concrete/ metal roof will absorb and radiate heat throughout the day. This will cause the room temperatures to rise well after the sun has set. The West and South facing walls will increase the load. With the air conditioning trying to counteract the constant flow of heat. Insulating the roof, and walls if possible, will help reduce this.

Reduced Solar System Size

There are three reasons why insulating will reduce your Solar System.

1. Reduced Load During the Day

By reducing the heat entering the building, less work will be required by the AC compressors. This will reduce the total amount of electricity used during the day. This can mean a significant reduction in system size recommendations based on your building. You’ll save on the panels, fixings and inverter.

2. Reduced Battery Size

The batteries can be one of the most expensive parts of your Solar System. The biggest drain on your batteries will be during the evenings and at night. An uninsulated building will constantly radiate heat causing your AC to work hard after the sun has set. An insulated building will maintain a comfortable temperature for longer meaning less load during the evening. This will allow you to have a smaller battery.

3. Reduced Air Conditioning Size

If your building is well insulated, the load for cooling will be reduced. This can mean less air conditioning units or smaller units for new builds or major renovations. Reduces your capital costs and solar capacity requirements.

Net Metering

Rules and rates for exporting excess solar can vary in Pakistan and may change. Always check what the current rules are before making your business case. However, if the value on the electricity you are exporting is less than the value on the electricity you are saving, you’ll get the best economics from using your own electricity. The most benefit will be gained from efficient buildings as they will be using the electricity they produce.

Best Buildings to Insulate

• Residential with concrete roofs. Usually the top floor will be the hottest and most costly to cool.
• Factory/Warehouse with metal roofs. Large roof areas will absorb a lot of heat. Insulating your roof can reduce a large load. See our guides for Commercial & Industrial Roofs.
• Office, Schools, Clinics. Loads will be predictable during the day meaning less cooling requirement = smaller system.
• Cold Storage/Air conditioned areas. Cooling load will make up a large portion of your bill. Insulating the building envelope will have a big effect on system size.

Usually the best order of Work

If you are planning on doing both is:

• Look at your electricity usage. Check your bills for the past year and look at your summer months. This will show how much of your load is going on cooling.
• Insulate your roof. Usually the most effective and quickest payback.
• Insulate walls, windows and air leaks if possible. Especially West/South facing.
• Get your load measured or talk to your solar designer to factor this in. Size your system based on the new reduced load. Get some quotes.

If you are going to install solar first due to budget/time reasons, you can still insulate. Let your designer know to ensure you don’t have an oversized system.

Don’t Expect Miracles

Depending on the building type, roof type, orientation, existing insulation, AC efficiency and usage, you’ll see different amounts of savings. Insulating will reduce your cooling load but won’t replace efficient AC, shading and good draught proofing. Solar should be designed and installed correctly to give you the correct benefits. Ask for calculations specific to your building. Don’t expect someone to give you a general % saving. Be wary of anyone that gives you a fixed % saving without looking at your roof and bills.

Solar Panels on Roof

As an added bonus, having solar panels on your roof will provide some shading. This will further reduce the roof surface temperature. If you have a roof that will have panels on it, plan your insulation and waterproofing first. Once the panel structure is installed it will be much harder to work on the roof.

Why Insulate?

Many owners in Pakistan are turning to solar due to high electricity tariffs. However, the cheapest electricity you can get is the electricity you don’t use. By insulating you’ll be reducing your demand for decades, saving you money on panels and batteries. An insulated building will provide more comfort on days when your system isn’t producing. If you are planning to install solar, it’s worth preparing your building.

FAQs

Should I insulate my roof before putting solar panels on?
In most cases, yes. Reducing your cooling load will reduce your Solar System size. It will also be much easier to insulate and waterproof your roof.

How much smaller will my system be?
This depends on your building, roof type, current cooling load and usage. Speak to your insulation provider and solar designer to get an estimate for your building and bills.

Will it reduce my battery size?
It can. An insulated building will have a comfortable temperature for longer after the sun has set. This will reduce your evening and night cooling loads.

Will it still be worth insulating if I already have solar?
Yes. You’ll get more of your solar output to be used for other purposes. Less reliance on the grid when your system isn’t producing. More comfort. Let your solar designer know so they can optimise your system/batteries.

Which buildings benefit most?
Buildings with large exposed roofs and high cooling loads during the day. Examples include residential buildings with concrete roofs, factory/warehouse with metal roofs, office, schools, clinics and cold storage.

Contact Pakistan Insulations today for a free consultation and quote.
Phone: +92-21-34529722
Email: [email protected]
Website: www.pakinsulation.com