Beckett SolarHot - Manual (Page 9)

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© SOLARHOT 2006-2009
• Second, the sze of the storage tank controls how much of the heat that you absorb n from the
collectors that you can keep. If you have a storage tank that s too small for your collector area, you
wll heat the tank up very quckly and then the system wll ether need to dump the heat (n a glycol
system) or just st there. If the storage s too small (40 gallons), you wll rapdly deplete the heat
you have stored and then switch over to auxiliary heat. Because a solar hot water system is just
that – a system – f you cut corners on a sngle pece of the system you are mpactng the overall
performance of the system. An 80-gallon water heater s only $100 more than a 40-gallon water
heater so no need to put $3000 nto an nstallaton and only get 50% of what you could have gotten
had you put n $3100.
• Third, how efficiently the heat from the collectors is transmitted to the storage tank.
Sizing the Storage Tank: The sze of the storage tank s also dctated by where your geographc
locaton. If you lve n the Sunbelt, you should have 2 gallons of storage for every 1 sq. ft. of collector.
In northern clmates, we have seen systems as low as 1 gallon of storage for every sq. ft. of collector,
but you should am for 1.5 gallons or more of storage for every sq. ft. of collector.
The Beckett SolarHot Advantage: Our system ntegrates hot water tanks of multple
capactes nto the solar system. Ths creates a scalable, economcal soluton for your
hot water storage needs. These tanks come wth bult-n electrc heatng elements
for those days when the system needs auxiliary heat to meet the hot water needs.
We have covered the gudelnes for szng collectors as well as the storage tank. There are a couple of
overrdng factors to consder when tryng to sze an nstallaton. It wll take the same pumps, controls,
ppng, ppe nsulaton, and valves for a small system that t wll take for a large system. Be careful of
szng a system for the mnmum when you could cover a larger % of the hot water load and allow for
future famly growth or the sale of the home to a larger famly for only a slght ncrease n ncremental
cost.
Example: A couple decides they want to do their part and install a solar hot water system. Based
on the calculations they need 40 sq. ft. of collector area and a 60-gallon tank. To cover a larger
percentage of their hot water load and to take into consideration future family growth or sale of
the home to a larger family, I would recommend installing 64 sq. ft. of collector and 80 or 119 gal-
lons of storage. The incremental cost would be around $500, but the additional usability of the
system would be much greater.
Tanks come readly avalable n 40, 50, 80, and 119 gallons. They can be combned to make storage
systems of whatever configuration you want, (i.e. two 50s to make 100 gallons of storage). When you
start usng components of a non-standard sze, the cost (partcularly the cost per KW) of your system
rises pretty quickly. I have found on hot water tanks it is significantly cheaper to use groups of standard
sze hot water tanks (40, 50, 60, 80, 119 gallons) rather than use specalty tanks or tanks larger than
119 gallons. So, for a household that requires 64 sq. ft. of collector area, I would use 2-4’x8’ collectors
and ether an 119-gallon storage tank or an 80-gallon tank plumbed wth a 40-gallon tank.
Total Ft.² Gallons per ft.² Gallons of Storage Rqd.
64 1.5 96
64 2 128