Solar Hot Water - Residential Info

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 - Apricus Solar Hot Water Essentials

Due to it’s double wall evacuated tube construction the collector works especially well in the cold and cloudy Pacific Northwest. The vacuum tube allows the light to pass through the outer layer of glass and through the vacuum where it is turned into heat ( almost 80% of the solar energy collected) when striking the dark surface on the second glass wall – see photos below). There is minimal loss of heat to the atmosphere even in cold weather given the insulating properties of vacuum between the two walls of glass.

When it gets really cold the collector can still generate hot water at 5 – 10 F.

While Setanta Solar does not perform installations we have a family of dealers who are available to provide professional installation and support.

Installed Cost:-  A full system ( using the AP-30 Collector) installed including either an 80 or 120 gallon (electric backup) water heater will cost in the range of $9,500 - $10,000 before incentives

Tax Credits/Incentives 

Federal Tax Credit of 30%, State of Oregon Tax Credit up to $1,500, Energy Trust Oregon up to $700,Clark County- $500; Tax credits and incentives generally cover about 50% of the cost

The Collector

Base unit Collector is 30 tubes although sizes are available for 10 and 20 tube systems.

The designation for these units is AP-10, AP-20 and AP-30.Up to five (5) AP-30 collectors can be connected together. On a cloudy day the collectors can capture 40% of the heat they would have had the day been sunny.

Collectors operate effectively at very low temperatures providing hot water at 5 – 10F and warm water at -5F. In full sunny Summer weather they will generate up to 70-75 gallons of hot water per day. In Winter with cloudy weather the yield could drop as low as 20-25 gallons per day

In areas East of the Cascades winter yields of 45-50 gals are achievable as the units work well in cold sunny weather.

How does it work?

With their rounded tubes and internal aluminum heat transfer fins the collector functions in passive solar tracking mode providing optimum collection of solar energy throughout the day and not just at Noon. .

The sunlight passes through the first glass wall, through the vacuum and strikes the black absorber surface converting the light to energy – the metal fin inside the tube collects the heat, transfers the heat to the heat pipe. In cold weather, the dual walled vacuum tube construction dramatically reduces the heat lost to the atmosphere.

The heat pipe has a drop of water in the bottom which is heated by the surrounding metal and converts the water to steam rising through the heat pipe to the copper bulb (heat pipe condenser) on top. The bulb, inserted in the manifold passes it’s heat through the manifold to the glycol/water mixture moving through it. In the process of giving up it’s heat the steam condenses and returns to the bottom of the heat pipe to begin the process all over again.

Each time the pump circulates the fluid through the collector the temperature of the glycol/water increases by 9-10 F degrees.

After the fluid leaves the collector it is returned to the heat exchanger in the solar storage tank where it heats up the water in the tank to be used as domestic hot water. The fluid in the heat exchanger is returned to the collector for reheating and the cycle begins all over again.

Our collectors are extremely efficient ( up to 4-5 times more than photovoltaic panels used to generate electricity) capturing up to 77.8% of the sun’s energy that reaches them. Evacuated tubes also have the ability to capture energy from light from all four sides especially when installed on a bright surface – they can be installed on a roof, flat or pitched, on a south facing wall or ground mounted.

Daily Operation

At night time or when the hot water tank is fully heated the system shuts down. In the morning the controller monitors the temperatures in the solar storage tank and the collector.

When the temperature in the collector is 12 F degrees warmer than the bottom of the tank water the pump will begin operation and move fluid to the collector for heating. The controller continues to monitor the tank and collector temperatures and when the collector is 4 degrees ( values are programmable) warmer than the tank the units shuts down.

Maintenance

Little maintenance of the system is required. In dry areas an occasional washing off of the dust that accumulates on the tubes will help with performance. Treating the collector glass with Rain-X has also been done to allow debris to be washed off more easily. Every 3-5 years the glycol in the closed loop will need to be changed. In areas where the collector gets very hot for extended periods of time or there is no usage for several days ( vacations) the units may overheat and require a change-out of the glycol. An additional unit, called a heat dissipater can be installed to route the glycol/water ( still in a closed loop) outside for cooling and thus prevent overheating.

Warranty

Installation and parts warranty are provided by the installer and vary based on State or local requirements.

Apricus warranty on components is as follows:- Tubes  - 10 years; Heat Pipes - 10 years; Manifold - 15 years

System Cost

In order to receive either Federal/State tax credits, Energy Trust or Clark County Washington incentives a full approved/certified system including the collector, hot water tank and supporting components must be installed.

Setanta Solar LLC does not directly install systems but we can arrange with any one of our family of professional dealers to work with you.A standard family solar hot water solution, an AP-30 system with all of the required elements runs in the range of $9,500 - $10,000+ installed depending on the installation complexity, permit requirements etc.

Incentives include:

Federal tax Credit of  30%, State Tax Credit up to $1,500, Energy Trust Incentive up to $750, Clark County, WA -$500+