Solar Installation Case Study - Solar Home Office

Customers Brief

I have an outbuilding at the bottom of my garden which I would like to make into a home office, there is no power to the building and i was wondering whether this would be possible do do with solar.

What items need powering?

We contacted the customer to establish what he wished to power, how long he wished to power them for and a target budget

The system he required was calculated as follows:-

Component	Hrs in Use	Wattage	Total
Desktop Computer	5	100w	500
Printer	0.25	100	25
Telephone answering machine	16	10	160
Shredder	0.25	100	25
Scanner	0.25	14	3
2 x Low energy Light bulbs	4	18	72
TOTAL			783

The customer said it would be in use all year round.

Our Recommendations

We recommend having a large enough battery to store a weeks worth of power so the battery that would be required for this system would be the equivalent of 4 x 200ah 12v batteries. We use the figure of 2hr sunlight in Winter and 7hrs in summer to estimate power needs. In this system a 400w panel would be required. This is calculated by the total wattage used per day divided by winter sunlight.

The system we recommended was:-

350w Panel, 30Ah charge controller, 600w inverter, combined with 4 x 200ah batteries, lighting and wiring. The total system cost is £3,700. Mounting for the panels would also be needed and for this system the price would would be £125 for roof mounting or £250 freestanding.

We suggested the following to reduce the system cost

• Switching from a desktop to a laptop
  
• Having the answer phone in the house rather than in the office.

The power saving on these two components will save 335watts per day and shave £1,700 of the final figure (a nice laptop and office furniture can be purchased £1,700).

The Final System

This customer did decide to treat himself to a nice new laptop and decided that with his laptop he could work in his house in winter meaning even less panel was required as winter operation was no longer so important. The final system was a 100w Panel, 600w inverter, 30ah charge controller and 2 x 200ah 12v batteries, roof mountings for the panel and all wiring and light fittings. The customer chose to have a more powerful inverter and charge controller as well as heavy duty wiring in order that the system could be upgraded at a later date. Total price of the system finished up at £1,800.