October 11, 2017

Which solar water heater to buy

Which is the best solar water heater to buy which will suit my requirement ? This is the primary question that troubles every new house owner these days. Some state govts have also made it mandatory to have a solar water heater installed. So, here are some of the points to consider before making that purchase.

What is the quantity of usage ?

How many people live in the house who use hot water and do you use just for bathing or to wash clothes / utensils etc ?

Just for bathing purpose, consider using 100LPD for 2-3 people, 200 LPD for 5-6 people as a guidance. You will get an idea of the usage. Accordingly plan for capacity

Flat Plate Collectors (FPC) or Evacuated Tube Collectors (ETC) ?

ETC based solar water heaters are known to perform better than the FPC. If you have hard water, ETC model is recommended. If you have soft water, FPC model is recommended. For a more detailed explanation read this article – Flat plate collectors vs. evacuated tube collectors

Tank material and tank thickness

Heat retention and corrosion resistance are 2 important factors to consider.

The durability of your solar water heater system is largely dependent on the tank material. Typically solar water heater maintenance issues originate from the tank. Hence, it’s very important to consider the tank material and it’s thickness to understand how long it will last.

Typically if you have soft water usage, it’s enough to have a tank made up of GI coated mild steel. However, if you will use bore well water or generally get hard water from your tap, it’s recommended to use Stainless steel (SS304L food grade quality) or Hot dip galvanized (HDGI) tanks.

The pricing of the system varies largely based on the inner tank material and thickness. So, think before you buy a solar water heater just because it’s cheaper. In the long run the maintenance cost will become very expensive.

We offer HDGI tanks (also known as GP steel) with 10 year replacement guarantee in case of corrosion. These are highly corrosion resistant and the long durability of your solar water heater system is ensured.

We also offer copper tank for your solar water heater which has high heat retention capability.

Do you have hard water problems ?

A simple water test can determine what is the TDS (total dissolved salts) present in your water. If it’s high (> 250ppm), most ETC based solar water heaters are able to handle that. However over a few years, the hard water will start taking it’s toll on the solar tank and piping systems. The calcium and magnesium salts will start depositing inside and start to corrode them. This will result in fast degradation of the solar water heating system whichever brand you buy. This will result in repair costs much earlier than you thought. We get calls from customers who have installed the equipment for just about 3 years and tanks have started leaking. Here, we recommend using a scaling prevention system (from 3M as this does not use electricity and works on patented filtration technology that reduces scaling without losing essential minerals). So, even if the costs are slightly higher, as a combined system, in the long run, the combination of solar water alongwith a 3M scaling prevention system will save costs big time and saves you trouble from frequent maintenance of plumbing systems.

See here for more details – 3M whole house scaling prevention system

Do not buy because it’s the cheapest available

Last but not the least, do not buy a solar water heater just because it’s cheaper than the rest in the market. Please evaluate all the options mentioned above before you make up your mind. There is a strong reason why people go for established brands like V Guard, Swibe and Kayaka. There are 100s of solar companies who made money and shut shop when the boom stabilized. Customers now call us and ask and complain about those companies. Even though their systems are under warranty, the company itsef does not exist to service them. So, think long term and buy from companies who are around for over 10-15 years and have a sustainable business.

Warranty

Be mindful of the warranty. It does not typically cover the entire solar water system. Warranty applies only to the tank. Companies will make you believe the warranty is for the whole system. If that is the case, ask them to mention in writing.

In our experience, we have seen that most people forget where they kept their warranty card. Companies take advantage of this and deny service. So, keep the warranty card safe and handy to be used if need arises. We do get calls from customers of other solar companies where the tank leakage has started but the company does not exist or it denies service due to missing warranty card or applies additional charge for service. Hence, it’s important to know how long the company has been in the industry.

 

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